NASA_Fusion_Energy_21st_Century_Missions_1991

similar

safety

fusion

later

that

1-7

the

1.0 Introduction

to that study’s completion,

the widely ranging mission applications,

Taking today’s fusion research status into account, we note that a number of new developments have taken place, particularly with regard to the viability of the low neutron producing fusion fuel reactions. Those fuels are particularly suited to space program missions and, in fact, they have greater applicability and advantage to the space application than to the commercial power plant fuels.

Subsequent the Air Force concluded that no Air the Force mission in the fusion energy level existed and decided that recommended follow-on work would not be pursued. Later, however, a one year, $150K contract with McDonnell Douglas Astronautics was awarded through the Air Force Rocket Propulsion Laboratory, the purpose of which was to advise the Air Force on the prospects of using fusion for space propulsion for Air Force missions. That report has been recently completed (Hal89). Many of the conclusions made in the the Air Force study and this study are similar although there was no collaboration between the two.

Furthermore, the progress in the DOE program, and the terrestrial program’s developmental status stress the importance of dealing with this matter now. Both the DOE Magnetic Confinement Fusion (MCF) program and the Inertial Confinement Fusion (ICF) program have made some very significant advancements. The development activity for space fusion energy will involve a considerable period If fusion energy were available now, substantial program operational of time. savings, amounting to tens, even 100’s, of billions of dollars, would be realized by reduced operational costs.

Next, the value of high energy to the manned interplanetary missions with respect to the safety of the flight travelers is apparent when one considers that the radiation exposure hazards, and the physiological problems are all reduced by shorter trip times. Cosmic radiation, integrated over a period of time as experienced during a chemical propulsion powered Manned Mars Mission, is perceived to be a serious safety concern at the present time.

In addition, renewed interest in advanced planning in NASA was stimulated at the start of this endeavor by the President Reagan’s request and from the charge by Congress, to “formulate a bold agenda to carry America’s civilian space enterprise into the 21st century.” (Pal86) What could be more bold than to undertake new energy developments leading to the settlement of the solar system and to missions to the stars? A related review of new space endeavors culminated in the report, NASA, Leadership the

the time available for the conduct of science is Another advantage is that lengthened by the added mission capabilities, made possible by the additional payload mass. The vehicle’s payload mass fractions are increased, making more massive payloads possible and thereby effecting economies of missions. Safety also requires greater mass for shielding of the flight crew and to provide options for safe flight operations.

the psychological difficulties,

the timeliness,

Future in Space,

and America’s

1-8

than

some

starting

including

Consider

resources

November

the use of

the mining

large solar

the various

Just consider

bold missions

the importance

of Exploration’s

like the Office

We can conduct

source of energy,

1.0 Introduction

megawatts logistics

thinking sponsored

pilot study which examined

Space Policy was written,

effort and used as an input.

The availability new horizons

to space science and exploration

dreamed. to the forefront,

lunar of helium-3 power

2, 1990, affirming (Anom89).

of any large, specific for NASA.

applications, and the construction

such as fusion, will open ever

previously come Enterprise commercial applications materials.

results of which were presented to NASA during March 1987 (Rid87). An advanced missions planning office, The Office of Exploration, was established to continue the planning. On July 20, 1989 President Bush requested Vice President Quayle to chart a new course for the nation’s space program, one The NASA response was which looks to the moon, Mars, and beyond. prepared by a task force during a 90-day study of a human exploration program (Anom89). A draft of the Executive this high energy mission report Summary A revised United States was provided to that the United National States commitment

Fusion savings otherwise Fusion energy mission Under a large number of small payloads chemical the advantage lowering mission costs and improving requirements.

science too Is Earth the final phase of “space flight,” or are we going to

Further, consider program mission objectives distant remote sensing get involved allows?

to cost on any given flight which possible. space

fusion is the most viable high energy candidate now is the appropriate

launches vehicle substantially the launch operational

to Space large scale terrestrial using lunar of

From the results of this analysis, source to consider;

objectives feasible a very significant

with further the near Earth missions

of to a Martian settlement

future. Where will we look for energy beyond

out multiple mission be economically

are required A high performance

it. The key issue to deal with is not what

Attention of providing requiring

energy, by carrying could

using a multitude fusion

that number and from that perspective,

out have been flown,

energy that development

now underway. systems,

the more specific But

the current mission performance

power and high performance

fuel satellites of

sources which are capable

turn toward specific

higher preparation

the demand will be for

will be time consuming,

high energy missions.

in the future mission

or any high specific

factor equations

the above rationale,

of powered

to be accomplished

due to low energy

safety by reducing

the technologically

it can accomplish

can be expected

time to consider

those missions?

and in view of

can contribute

higher power.

can potentially

the availability

to gigawatts

low energy

of electrical

of reducing

for NASA’s

architecture

to become

exploration

in the not

restrictions

technically

propulsion

for for

by has

systems.

relatively

planning

potential

support.

become

system,

difficult,

current

energy

and/or

power

never

easy,

After

now.

than

that

our

1-9

will

for

that

fusion

January

enabling

A (Sch91)

technology

a concerted

as Appendix

the advances

and enhancing

ready reference.

space missions,

in the terrestrial

1.0 Introduction

program, fusion

by NASA for application

of in advanced

1991 issue which is provided

study effort was made by the author

the Lewis Research Center,

and the belief space to the space

and bibliography are discussed in Fusion

the renewed does energy be which should

much as the question of how viable is fusion as an energy source for space missions. That is the issue on which space resources must be focused.

Under the current strategy, no effort exists for space fusion research. Actually, a fusion program would not commence a new discipline to the agency. Earlier in NASA’s history, 1958-1978, a modest fusion research program was established and research performed at in the Advanced Concepts Branch, Electromagnetic Propulsion Division, to pursue fusion energy conversion and applications for space. That activity was terminated in 1978 in the wake of the many cost reductions that NASA underwent during that decade. The program, contributions, Technology,

In the light interest offer a potentially researched programs, the application of expertise universities made to the University Livermore National to the Los Alamos 1988, Princeton Plasma Physics an independent and discussions disciplines.

and the Lawrence during the latter part of August and in September in October

scientists as well as from the available of

and science analyze using the and site visits were

powered mission flight of that

Accomplishment beyond Mars, trip time limitations.

safety of safety later. Although

exploration could not be considered

and to the reflects the results of

Laboratory in 1989. This report

the solar can be implemented

those due to power and

Improved times discussion

As an enabling missions:

as a result of more massive

the literature and fusion

flight. is enhanced

establishment economical

of a Mars colony which

reviews of science

of new science missions

it is too early to provide

This was accomplished

to space. at

the in a more

National Laboratory

then plus continuing

Illinois, University

system including

of new manned

goal of manned

with interested

that otherwise

of Wisconsin,

in the space

not otherwise

the National

of fusion

accomplishes

Attainment

by reduced

Laboratories

from fusion

commenced

Specifically,

capabilities.

to carefully

technology,

exploration

Laboratory

for NASA

individuals

it appears

It is clear

objectives

NASA’s

Research

literature.

missions,

practical.

intensive

research

strategic

manner.

payload

a topic

science

energy

fusion

space

times,

return

proof,

1988,

study

flight

1-10

that

For

least

future.

vehicle

and to

promise

intensive

available

to occur,

in space.

increases

Reduce

of energy

contender,

for space.

substantial

technology

equipment.

the prime

1.0 Introduction

to increase

of manned

requirements

the inherent

of heavy lift

If there ever

improvements

and utilization

are mandated.

at an affordable

less manpower

launch vehicles.

system designs.

Major economic

for large numbers

Higher efficiencies

fusion enhancing

is to be any hope that

program, perspective,

the payload mass fraction

in the cost of doing business

there must be an abundance

holds and reliability

for significantly spaceflight

cost. the for in specific

and its machinery safety

in mind to evaluate whether NASA should

has to be considered that

power must be achieved make

With the study objective space fusion management

potential will play a role in the wide development

Free enterprise free enterprise of space, Fusion foreseeable

it of space the to and the return from space, as well as the trip times to and the in

for which NASA has to high energy In part, some missions report (Don88) with

The rationale enable man to accomplish achievable

In the context encompasses transportation visitation Section

category already applications, were outlining astronomy,

objectives new missions by the 1988 National

Fusion must either be or

Some mission types have been not considered.

the missions where fusion can provide

science sun, and lunar science.

a map for an exciting the planets,

yields such as safety and economic

presented a new mission

two key fusion namely,

in a more cost effective manner,

not previously planned

categories

Exploration

Imperatives

from a high

space mission

1995 to 2015).

that can benefit

We can consider

in the Twenty-First

I. Manned Solar System

2.0 HighEnergyMissionApplications

HIGH ENERGY SPACE MISSION CATEGORIES

kWe. The largest power consuming application was 7 MWe, a cargo-carrying Interplanetary Transport Vehicle (ITV).

An excellent source for science mission objectives, representing the most advanced scientific mission objective thinking, was the NRC Space Science Board Report. (Don88 Space Science for the Decades

of manned exploration missions to Unmanned Mars are currently being planned and examined in depth for early in the 2000

and if it actually materializes or not, perhaps will depend

upon factors about which we are probably unaware today.

The ultimate goal now is manned Mars exploration

. Solar system ° Interstellar

year settlement,

Mission DescriDtion

science missions

I1. Space Science-

an event which,

EXPLORATION:

II1. Applications

ADVANTAGES

time frame.

OF HIGH

in support

ultimately

OPTIONS

Mars-and

MANNED

ENERGY

beyond

2.2.1

AND

2-13

will

the

and

The

was

play

high

must

there

small

could

study

Refer

Active

power

extent

permit

lander

in the

(MEM)

energy

in-flight

Module

factors,

specific

thereby

vehicle.

to Fig.

logistics

to high

whether

element

systems

practical

planning

enabling

missions

(Can68).

Rockwell

be very

endeavor

American

a major

for Mars

key in

capability.

propulsion

by North

exploration

the mass

demanding

to perform

accomplish

of NASA’s

is possible

of vehicles

or whether

the design

perspective.

commenced

undoubtedly

architecture.

permanence

performance

requirements

infrastructure

transportation

as a critical

the manned

is technically

a reasonable

will establish

High specific

be mandated

To investigate

A permanence

an economical

in the 1960’s.

space mission

viable. future

from a space

of high specific

In that role

by the availability

power whether

will be determined

for short durations

the establish

only a of man

payload necessity,

it of weeks.

determining Logistics

requirements, The

a study 1967 Manned

systems. a permanence

conducted Mars Excursion

2.0 High Energy Mission Applications

of high specific availability

of man at Mars will become of visits number very

propulsion Application aerobraking.

for Rocket combination

powered chemical

Vehicle with

Av KFPS (KM/SEC)

16-10.5 (4.9-34.2)

on performance

2.4 to observe

Mars Mission

fission and

(IsP= 8oo SEC)

(IsP= 800 SEC)

(IsP.,800 SEC)

trip Manned

the effects

MA,RS OI::_)ITCAPIUF:E

propulsion,

EARTH ORBIT ESCAPE

rv_kRSOP,BIrESCAPE

(NERVA),

the two

chemical

systems

showed

Nuclear

16 (4.9)

15 (4.6)

Engine

CASE1

CI-ENF.__.AL

CASE2

CASE3

AERCBRA#_

round

CI-EMP_,At

CHEMC.AL

O-E1vF.AL

NUCLEAR

IV_SSION

NUCLEAR

2-14

NUCtEAR

OPTIONS

that

CASE4

AE_

LLI

.05

10 2

ALTITUDE

PARIAPSIS

Applications

= 152 N MI

X ¢n ._J 72- “I-

MEM ISP = 383 SEC

MEM: (4 MEN, 30 DAYS)

2.0 High Energy Mission

CASE 1 : NUCLEAR-CHEMICAL-CHEMICAL

CASE 2: NUCLEAR-NUCLEAR-NUCLEAR

CASE 4: NUCLEAR-AEROBRAKE-CHEMICAL

CASE 3: CHEMICAL-AEROBRAKE-CHEMICAL

Martian stay and a day stay. Aerodynamic retro propulsion The initial vehicle mass was ~ 910 MT. A 50 MT payload was placed

the to the to be a the up to 900 or even 1000 risk limits to a greater the higher

into a Martian orbit. The Av requirement 4.9 km/sec. reduced the initial vehicle mass by only 16 MT in comparison

was determined technology Rockwell reasonable nuclear seconds. While that, incurred stressed

by the contractor Since the NERVA program was concluded that

to Mars was engine for Earth orbit escape with the chemical

Two missions were considered 2-man/4 at Mars.

propulsion propulsion The return engines lieu of a retro burn.

the return trip’s Av also. at Earth was used in impulse

We can also state the advantage versus

the heat exchanger’s for quicker, more massive

as a result of pushing load. Clearly thermal

then. Mars mission performance

provided Aerocapture specific

performance of greater fission

considered are extrapolating

analysis, goal although

system’s (400 seconds

(400 seconds impulse)

using fission. defined.

in that study, a 4-man/30-day

fission will be advantageous.

windows the mission

performance specific

to escape from Earth orbit

The value of 800 seconds

too, may be attainable,

burned FLOX/methane.

braking was selected

to be a reasonable

is still studies

value current

to perform a

is the degree

this mission,

is a function

for example,

the question

The answer

2.4. MEM study

performance

to chemical

and aerobraking.

If the goal

subsequent

for combinations

the fission

operational

in lieu of

is simply

Chemical

impulse).

payloads

engine’s

the mission

performance

material

Fig. 3-11).

specific

beyond

ALTITUDE,

APOAPSIS

use of

nuclear,

of energy

chemical,

showing

(Can68,

sources

2-15

results

N MI

For

10 3

10 4

10 5

as,

for

it and

Design

fission.

systems

in Fig. 2.5.

A description

Recommended

then chemical

can accomplish

the lander vehicle is provided

2.0 High Energy Mission Applications

the costs associated with qualifying

single manned Mars mission, without

The MEM would operations orbital scheduled capture checked from the spacecraft. predetermined prescribed up; vector adjustments.

The MEM is that spacecraft accomplished in Apollo in the following manner by Dr. Canetti.

Low thrust de-orbit motors would be fired at a in a Entry generally would occur with the lift

the equilibrium velocity of about 300 fps (0.9 km/sec) the difference

be passive and and interplanetary and maintenance

landing roll control would To decelerate

the Earth for except the Mars be

the and the MEM manned

be initiated at and applied between

4 MAN/30 DAY _,GcROSS: io9,oooLsS 7.4

and ascent mission The mission

phases profile is described

unmanned transit operations.

orbit out and activated,

would and separated

to effect entry and landing

of the descent

(Rockwell chart SD 67-755-4).

Fig. 2.5. MEM configuration.

by the Lunar Module.

for minor navigational

by the trans-Martian

time and position

during phases

JCHARACTERI STI CSl

to be carried

retropropulsive

to accomplish

shield would

be employed

thrust would

the payload

subsystems

the vertical

component

has been

the MEM,

the heat

achieved,

checkout

balances

and lift.

Portions

similarly

so that

portion

weight

area.

After

2-16

_V (e ,=0.9)

SLUGS/FT

ASCENT

30 FT

20,350

FPS

entry,

exists

during

before

Applications

landing,

capability

maneuver

performed

propulsion

connected

operations.

touchdown,

rendezvous

Touchdown

is imposed

for surface

and docking.

in Mars orbit.

are transferred

the MEM would

2.0 High Energy Mission

to the spacecraft,

landing site. Until

and living quarters,

payload abandoned

just before the ascent

the control cabin atop the vehicle.

to reduce weight. the final

requirement stage must be separated,

and on the The most when the and a

before there is no abort capability

would occur after a short the crew

Normally, orbit and, after appropriate

jettisoned hover period over would occupy

entry. touchdown engine ignited, orient

the control equipment tankage the MEM would

Abort Mars surface; critical ascent turn-around vector.

to the control cabin by At and structure would be left be staged would ascend to an intermediate phasing with the spacecraft the crew and scientific After

A laboratory a tunnel and airlock, would be provided lift-off, much of on the surface; ascent. phasing orbit, effect

The other proposed nuclear was for Earth-moon transfer. associated aspects and safety class for trips to the Moon, NASA removed nuclear application feasibility

The study concentrated vehicle mass would energy would meet would be required. performance not to accomplish required propulsion/aerobraking for the mission considered

that complexities design from future space the that point propulsion was well demonstrated.

propulsion mission under consideration the operational of

or whether The conclusion a Manned Mars Mission. was better

Fusion power and propulsion application Some thoughts

low such that current higher was that

propulsion and research on it was terminated.

as a requirement advanced missions.

propulsion fission The existing

As a consequence with nuclear

be sufficiently requirements

equations below in that

considerations, the thermal

have not yet been inserted

on the Martian operations

propulsion system

chemical standpoint

of propulsion

to establish whether

for Mars and other

from a performance

Advantages sources:

fission technology

and the projected

levels assumed.

to the planning

of high energy

Reduced

are provided

the NERVA

performance

to correctly

over other

the thrust

technology

Safety

propulsion

the MEM

trip times

chemical

systems

regard.

energy

fusion

2-17

time

for

study

shows

Earth

triD times

a two week

that a fusion

Reduced
Space manufacturing
New missions enabled
Environmental benefits
More massive payloads
Economy of space travel

2.0 HighEnergyMissionApplications

High payload mass fraction vehicles
Conduct of more science more quickly

One recent including days enabling

Greater operational flexibility in mission planning.
Sustenance of man for a permanent presence of man beyond

The time the current are there for a manned Mars program which

Safety Mars one-way paid for penalty which planning significant health may be acceptable for settlement.

in Section trip time of up to nine months the use of

over a 1-2 year masses in this section.

have obvious as well as from a cost and

round trip mission to Mars, time of 90

performance operational function presented

provides time mission. and

Trip times as a are

but which may be unacceptable

Propulsion from a safety

flight for manned

stay, can be accomplished

use and safety

9.0. Some major points

within trip times

follow. significant

for a one flight mission

the major environmental

savings of vehicle

These then constitute

Study”). viewpoint

Under systems,

Space environmental

A 90-day mission

lower performance

low performance

3- psychological

4- physiological.

2- solar events

exist, galactic

power/impulse

High specific

Two sources

is discussed

perspective.

advantages

1- galactic

substantial

trip times.

unmanned

is a very

to control:

propulsion

of natural

by virtue

(Anom88:

payloads

systems.

the first

radiation

powered

hazards

reduces

hazards

“Fusion

shorter

a total

further

Short

flight

2-18

later

two

flares

fusion energy,

Protection from solar

2.0 HighEnergyMissionApplications

What can be done to protect the crew? A small shielded safe haven is It is certainly a strong design option for perhaps the optimal solution. emergency use in the event of an unexpected solar event. Limiting launches to periods of anticipated cycles of low solar activity cycles will surely be exercised. This subject is explored further in Appendix B which presents another approach to the use of referred to as “LASERPATH.”

cosmic ray exposure and solar flares. For cosmic rays the dosage severity is determined by the exposure duration. From exposure to cosmic rays plus secondary radiation, the flight crew can be exposed to their dose limit within a short time, i.e., at the dose of 0.1 rem per day a space traveler will receive in 50 days the 5 rem limit established for the clean-up crew during the can be Three Mile Island accident. accomplished but with a mass penalty. A severe flare will otherwise be fatal.

The effects of being enclosed in a small space for nine months causes great concern for the psychological aspects, or mental health, of the flight crew. There are questions concerning the psychological fidelity of ground testing and its true capability to simulate the realism of not being able to rapidly return to Earth in the event of a contingency. Test subjects are obviously aware that they can immediately “return to Earth” in a very short time, if necessary. A sufficiently high power system can alleviate the concern by providing propulsive braking and power for return to Earth abort (RTE). RTE abort is a very important concept for safety that will be mandated if the vehicle performance capability were attainable.

Long duration trips impose a severe penalty upon the crew due to the physiological aspects of extended periods of weightlessness, and it is a subject under considerable research, especially by the Soviet Union where the conduct of a series of orbital weightlessness experiments, now in excess of one year’s exposure to man, have been methodically under way for many years.

10 MT payload mission to the nearest are presented

can be more and 10 MT returned mass while a

of manned and 60 MT returned

High energy 130 MT outbound

the consideration to Mars

on the order of on a

. M_;_;ive payload transportation

on the order of 20 MT outbound

star can be examined.

reasonable massive,

to be considered

in this section.

to the planets

The results

time scale.

payloads

Science

allows

flight

2-19

later

For

power

distinct

specific

present

Applications

benefits

element,

elements

concerns

elements:

discussed

categories

habitability,

have been

environment

performance

the second

an adequate

the provision

2- habitability

the naturally

environmental

for a suitable

Environmental

I_nvironmental

life supporting

of environmental

from the safety

2.0 High Energy Mission

3- waste products.

for man on a planet

1- space environment

power aids the second

The space perspective.

phase are anticipated

are reduced radiation for man’s habitability,

Three separate, by high environment, and the environmental

environment impact due to man’s generated waste products.

High specific enabling body. duration primary practical a sizable than the confines rather craft cabin as used in Apollo or designed for an advanced breathable the implementation addition, Power power person materials dominate

The third waste. discussion use of chemical energy Martian orbit and on the Martian surface. will A wasted in jettisoned around Mars for each return flight There resolution. first place. mass will permit mission designers

in the the for both in a Each landing and launch at Mars in orbit vehicle remain a space debris problem. now, without

in Earth is to avoid the problem in the greater to transport that

be a this require landing features recyclable, conditioning, source.

on an extraterrestrial exploration, Self sufficiency technology

work related functions. but a lunar base mission an independent

stay times program objective. is an abundance habitat

environment of manned Mars (Pai86). key enabling

contained, plant growth; water; and temperature

is a concern Obviously The high specific

estimates level of 2 MW was determined

including and mining (Fri88). Materials

the mission will suit or small Essential

will avoid the generation provide

The goal would be to the use of a

described The penalty debris,

extended will making

base processing, the power

scenarios of this section.

the use of space flight equipment

about the preferred

there will be power demands

of orbital and surface debris.

factor the mission

a sufficient mass-to-Mars

energy mission capability

of a space for

of which will depend

upon a large energy

debris approach

is in the generation

to Earth, creating

concerns man’s

for Mars could

that will permit

of the MEM at

This phase of

not be found,

for supporting

in the studies

the beginning

to accomplish

environmental

the conduct

of significant

requirements

atmosphere;

operational

of human

processing

the MEM.

stage will

of energy.

generated

reviewed.

capability

Consider

science,

appears

include:

tended

habitat

debris.

a self

space

would

result

lunar

2-20

orbit

The

24-

for

will

the

per

For

and

The

total

than

level

time,

state

lunar

watts

since

value

1,000

costs,

times,

in-situ

study,

capita

guess

nearly

power

lander

ascent

hazard

current

and it

landers

Martian

citizens

person.

vehicle.

indicate

method.

program

it would

a crude

reusable

Because

transport

at Mars

materials

in space

utilization

for Mars

ultimately

distances

regarding

to hardly

advantage

the great

continually

on Earth.

processing

demanding

parameters

is possible

requirement

to happen,

substantially

Extrapolated

consumption

as a figure

consumption.

be expected

will obviously

in-situ at

and therefore

will be higher

power over

in the US is

and long flight

~80 MW level.

linearly would

the environmental

become will

level today’s

that increase

of 250 GW used

and missions

of 1,000 That

be a very expensive

estimated million

that example,

refined. necessity

developed future

extrapolate persons

technology the present

predictions. and science

to a colony requirement.

at a steady which

of merit 1 MW power

2.0 High Energy Mission Applications

the state is in its infancy

power is approximately

Our understanding requirements

An unknown/undefined on Mars

The wind is not a dependable

developed. can act as more

neutron that will probably

capable by the transfer

Fission significant of

a the use and the

and on Mars because

consequently, consideration

cell efficiency only

are required quantities

offers that supplemental

water may mass

safe, of cryogenic

before of electrical

refueling the fission

proposition. additional

Significant than

the technology

this much we know.

thin There taken

require of water

energy it clearly

will, capacity,

to the Friedlander

will be a part of

A key advantage

to be conducted

gains buffers

is to develop

is unavailable,

an alternative,

and that can

is minimized.

to be highly

from mining

the absence

be available

For Martian

Underground

of electrical

the energy,

its naturally

to examine

conversions.

atmosphere.

As another

for D-3He,

To provide

for coolant

for energy.

well-defined

transported

parameters

to provide

is realized

operations,

by nature

exploration

alternative,

concerning

processing

conversion

and wind

are, into

emissions,

advantage

if proven.

to Mars,

performed

expensive

significant

chemicals

gradients,

especially

and cost

of being

a source

quantities

at Mars,

intensive.

purposes

is used,

occurring

to store

rejection.

in trade

A study

chemical

electrical

alternate

research

radiators

outcome

function,

geology,

between

To use

in solar

as the

if direct

systems

pending

sources

a very

science

mission

energy,

thermal

surface

source.

viability

reveals

cooling

studies

ground

require

reactor

energy

source

means

power.

factors

unless

leaves

simple

and/or

fission

liquids

fission

to be

power

where

fusion

plants

fusion

in-situ

waste

unlike

would

future

solar,

could

small

of of

there

used

have

offer

2-21

heat

their

they

very

only

that

and

can

has

are

but

the

will

for

the

are

and

The

very

lunar

10.0.

other

totally

similar

wastes

issues.

so that

volatiles

savings.

handling

eliminate

The they

resources.

the mass

in Section

settlement,

is discussed

environmental

Environmental

local planetary

in Section 9.0.

or abandonment

but by that

by a substantial

fusion decrease

issues are discussed

Enable new mi_i0n_

advanced should

in low Earth orbit which

requirement use of

Economy of sDace travel

require life. That will

special raise attendant

Ultimately addressed -“How

fuels will not the issue

2.0 High Energy Mission Applications

capability enormous of 3He

to reduce the costs of doing business

time we will become more knowledgeable

reactors which will of useful conclusion

that factor. the reactor’s

the reaction could become more purely aneutronic.

eliminated?” problem, Perhaps physics

This topic reduces cost anticipated of

The high performance effects from the mining

after for the Martian environment radioactive

issues will have to be that we must now face here on Earth to be

From the science mission fusion transporting instruments transportation discussed

it is in the most planet but by providing lunar volatiles earlier. as propulsion,

that lifeless aspects, the use of 3 as mentioned gases as well capability

is very topic which is in need of for beyond the

by power bit and for of more science power as

NASA the Utilization for important when one considers

The OAET University Space Engineering of Local Planetary Resources)

and Exploration Research CULPR (Center is especially

the means by which a from the life support Another

exploring not just necessities. as a by-product

data which permits and orbital missions.

Center perspective, important. research extraterrestrial

the mining of helium- life support That

for Space Automation research

hydrogen. in the Wisconsin

transmitting payloads surface

Conduct more science more Quiokly

system delivers 2.2.3.

for heavier for both

at a higher the delivery

development habitability.

Mars is clearly an excellent

and of Wisconsin

the details of which follow.

is the topic of this section,

perspective, more

essence, hospitable,

is another to make

of man for a permanent

exploration in order

of man beyond Earth

provided rate

is the use

in space through

by the University

From an energy

is being studied

can be made

on the means

of Aeronautics

and Robotics.

the abundant

the important

A sustenance

The volatiles

the science

the material

requirements

fundamental

Technology)

life support

the power

to provide

application

in Section

Planetary

produced

presence

including

available

location,

payload

oxygen

include

energy

rapidly

(Office

higher

allows

in-situ

That

2-22

The

and

to one that

fundamental

It is absolutely essential

2.0 HighEnergyMissionApplications

By today’s space transportation

moon, on which to accomplish extraterrestrial utilization research and to prove principles. that we learn the skills that develop the technology which uses extraterrestrial materials and resources. They are needed, not for transport back to Earth, but for local exploration cost and and settlement purposes. performance standards, transporting extraterrestrial processed materials will not be affordable, except in rare situations, such as, the mining of 3He on the moon or on other bodies in the solar system.

Conversion of an inhospitable planet’s environment is life sustaining and supporting is more than a science fiction fascinating subject; technology if man is to press his presence it is a crucial, beyond the bounds of Earth on a permanent basis - a third phase of the Martian mission. That mission can be anticipated to be of great benefit to us in understanding our planet better, a topic particularly important to “Mission To Planet Earth.” Martian exploration technology can be expected to aid in the understanding and management of Earth’s environmental problems. Then too, as we ultimately look beyond this solar system for settlement, it is conjectured that if a planet in another solar system is found hospitable to man, there is a reasonable probability that the planet will already have been occupied by a similar natural process of evolution with some type of native inhabitants. If this is indeed a correct conjecture, and then we obviously have either the option of passing it by or sharing it, depending upon the phase of its evolution. Planets capable of supporting life are considered to be very rare by some scholars of the subject, but that is speculative. Barnard’s star, at only 6.0 light years away, has held great interest as the promise of perhaps another planetary system. Some thought has been given to the subject of the production of habitable planets by Oberg, a process referred to as “terraforming” (Obe82). These and other missions discussed in the reference Hart and Zuckerman paper are of an advanced nature.

The presence of life beyond Earth is a deep rooted, fundamental question in analytical minds. Two NASA programs have devoted resources in pursuit of the question of extraterrestrial life, the Viking and SETI (Search for Extraterrestrial Intelligence). Much more can be done. The only known life exists on Earth; and the intelligent life here is, by astronomical standards, In terms of astronomical an event which happened only yesterday. dimensional scales, life is merely a surface phenomenon, that is, it exists in only a miniscule portion of the universe - a transition region, a boundary layer between the very dense massive regions, Earth, and the very tenuous but predominant region of the universe, space. Even within that sub-atomic dimensional scale, it is confined to a very narrow energy level of a few degrees. Yet there are billions of stars per galaxy and billions of galaxies within the universe. Are we really alone as intelligent beings in the universe? Are the Earth species the only type of life form? Solar system science objectives discussed in Section 2.2.3 include the gathering of basic

2-23

they are important

2.0 High EnergyMissionApplications

the determination of extraterrestrial

major new NASA space goal, in addition to understanding the origin of the solar system and universe and their ultimate destiny, is suggested, namely, life, particularly including the presence of planets having habitability characteristics and the detection of life beyond Earth.

information concerning life forming situations such as is proposed with Titan and the comets. But the Titan mission for life form evaluations is very limited - it must be. While these objectives cannot answer the fundamental question of the probability of planetary formation, to better understand life. The stellar mission category pursues the topic further; it is intended to address planetary formation in star systems and to address formations with older single stars as well as the most probable source for extraterrestrial life. The NASA goals in Section 2.2 pursue scientific knowledge of the universe, an expansion of man into the solar system, the conduct of aeronautical research. Forwarded here, then, is an additional thought reflecting the question of life.

NASA … will conduct a balanced program to support scientific research, understanding of: spread of life in the universe. (pp. 5,6).

In that context, as a first step, a visit 2.2.5. better asteroids, Sections

The CULPR is conducting for space shielding discussed manufacturing massive

structural metals, this capability of an develop is to least those otherwise

technology space the cost of space operations

That goal is compatible with “US National Space Policy” which states that:

is also required thereby logistics.

(6) the factors governing the origin and

for permanent in Appendix capability

in Section and for the in

and is also in-situ bulky, require

transportation in order dramatically

This self-sufficiency of outer

settlements. The B. to reduce

objective dependence which

As a corollary understanding

propellants, The benefits

to placing life’s origins

and experimentation

autonomy, and space

and Titan are particularly

$oace manufacturing

on Earth, missions

derived materials

2.2.2 and 2.2.3.9.

to Alpha Centauri

low technology

to expand

exploration,

a high degree

to the comets,

the technology

are discussed

to developing

upon space

from Earth.

to develop

is analyzed

decreasing

significant.

life forms

dedicated

emphasis

materials

including

research

These

on at

would

2-24

…

B).

unit

that

The

with

was

This

later

mass

Earth

those

lasers

where

extent

moon,

gained

logistic

thruster

vehicle.

granted

system.

ablation

as well

proceed

of man

approval

fractiqn_

systems.

into the

a higher

reduction

in 1988.

programs

variations

Lawrence

in terms

University

resources

Livermore

comprises

probability

on Earth.

of weight

economies

technology

Laboratory,

of Arizona

the launch

the Earth’s

Now if we

10 Provide

is discussed

improvement.

of magnitude

a decreased

high oayload

as to provide

For looked

The utilization

for higher

(see Appendix

in this section.

Mars, vehicle

by the That

Payload fractions

the use of a laser

important will

significant beyond

is a very costs

program expansion

remaining than

to a large flight

Dr. Logan, driven

are more as part of

The values topic

mass as permitted

high mass can achieve

research That the permanent

it can transmit for plasma

local planetary space in

2.0 High Energy Mission Applications

than an order the missions

program for accomplishing

solar consideration substantially

are decoupled by high performance

Martian source with energy

to an interplanetary level

be accomplished to the power

the performance launch

define are low mass

send discussed fraction

powered at a sufficient

by providing science

power, transmissions.

to Earth is propulsive

the Martian It offers

of storage higher

Early operational

through consuming

the objectives.

to either 2.2.9.

objectives orbits

Additional large

the use of chemical

a central device.

a new intensive.

planetary than

analyses for

be system’s

crew planning

by pure mission

element This,

energy rates

on extraterrestrial

as well as free

is a high power

will be required

can directly

rate of science

to quantitatively

be substantially

the transmitted

and payloads.

power These

at Mars will

by rather

the chemical

for a higher

is mandated,

and science

initial mass

has obvious

consequence

for example,

by a fusion

opportunities

Greater

is to delay

from Mars.

are gained

to conduct

the energy

on moons,

o.oerational

capabilities,

can meet.

in too,

in Section

of multiple

determined

extrapolate

intermittent

capabilities

exploration

consumers

consuming

substantial

contingent

propulsion

stationary.

a means

to safety.

objectives

a launch

increased

relevance

to Earth

planetary

reflecting

penalties

payloads

missions

provided

Imaging,

for use

in local

function.

outposts

A large

flexibility

stations,

systems

beamed

duration

orbiters,

weather

electron

remains

concept

payload

phasing

sources

(aborts)

number

thruster

science

devices

science

mission

missing

Mission

window

moons.

surface

several

a very

include

returns

power”

energy

rovers,

“space

source

Where

further

power

years.

return

There

which

Since

some

direct

could

mass

times

since

large

Mars

laser

flight

2-25

With

data

high

long

One

This

stay

soil.

The

and

that

has

can

etc.

are

not

for

and

fusion

analysis

probably

deliveries

to compare

of extending

In a recent

of Wisconsin

the same flight

the destinations:

time to each of

of Dr. Stuhlinger

the cost equivalent

has the consequence

have been analyzing

Mission performance

study, Dr. Santarius

PAYLOAD FOR SAME FLIGHT TIME

2.0 High Energy Mission Applications

the University energy.

Staff at of calculations

the program for a fusion to develop

the space application the low thrust used propulsion chemical

system payload the moon, Mars, and Jupiter, Fig. 2.6,

launch window missed minimum of 2 to 3 years, energy.

Fusion and chemical propulsion system payload deliveries for the same flight

in mission time for the same payload, Fig. 2.7 (Stu64).

and for the reduction

Earth-Jupiter 1000 days

Earth-Moon 5 days

Earth-Mars 260 days

Fig. 2.6.

2-26

time.

CHEMICAL

FUSION

c O

I&.

I.L

[]

”-’

I—

[] *

500-

900-

I00-

1000-

._ :_

Earth-Mars

Earth-Moon

Earth-Jupiter

50% payload

33% payload

_” 800-

Fig. 2.7.

300- 2oo-

__ 400-”

CHEMICAL FUSION

700- ¢pE 600-

FLIGHT TIME FOR SAME PAYLOAD

2.0 High Energy Mission Applications

Fusion and chemical propulsion system payload delivery time for the same payload

Payload mass fraction as a function of flight

a specific power of 1 kW/kg.

The payload mass fraction

time for a trip to Mars is

The above calculations

trade as a function

shown in Fig. 2.8.

time for a Mars trip.

O 0.4. < O .,.J >- ,,¢: 0_

assumed

Fig. 2.8.

(San88).

7% payload

ROUND-TRIP

o_ 0.a.

flight

2-27

(Months)

_0.8 O

TIME

“-i

0.2.

1.0

’

-av/gl_

time.

m/=moe

examination

a comprehensive

are the missions

that can be considered

2.0 HighEnergyMissionApplications

To provide these solar system:

These brief energy system analyses point the way toward substantial savings in mission flight time and/or the mass transported into LEO. The benefits of fusion for the high energy missions are graphically illustrated. For the moon, the performances are approximately the same for chemical and fusion; for Mars, a big improvement is realized from the fusion system; for Jupiter, a tremendous improvement is acquired. Figs. 2.6 and 2.7 point out the basis for the statement that fusion can be expected to economically transport large payloads over long distances. Fusion achieved a large gain in the payload mass fraction, i.e., from Large mass fractions are 0.1 to 0.6 without a large penalty in flight essential in lowering costs in any transportation mode and exponentially so in space flight in accordance with the rocket performance equation:

Manned Mars Mission performance part of this study. Mission performance McA88)

subsequent of the outer moons may be feasible.

for a design data from the SAIC calculations

to be too radiation indicate

Early intensive possible

study for manned

islCOMETS

data were calculated

point as (Fri88 &

O ANOSI

and Saturn were

of planetocentric

the calculations

return mission

for a manned

are discussed

are inclusive

requirements,

SOLAR SYSTEM EXPLORATION

and sample

for manned

of possible

rendezvous

discussions

considered

exploration

POTENTIAL MISSIONS

although

energy

in this

Jupiter

results

MARS

below.

2-28

The

and

MANNED

the

PLUTO

these low thrust calculations

2.0 HighEnergyMissionApplications

(~10-3 to 10-4 g) using the The results of aforementioned design data are presented in Figs. 2.9 through 2.12. Included are the results for Mo, Mp, Av, and Isp. Curves which show trends and tables which provide single data points are provided. The same format is used for discussions of all missions.

heliocentric times but exclusive of stay times, a propulsion independent variable for the purpose of this study. For these manned Mars mission performance calculations, an outbound vehicle mass of 133 MT was used, and a return mass to Earth orbit of 61 MT. These round trip missions were considered to depart from a 1000 km altitude Earth circular orbit and to park in a 500 km altitude Martian circular orbit. No aerodynamic braking was used in these missions, only vehicle propulsion, a safer mission operational mode. In this Martian mission performance analysis, only single stage vehicles are flown. This concept, therefore, eliminates the space debris issues discussed earlier. The payload masses were based upon the results of a Marshall Space Flight Center study (Anom87).

The text for each of the mission performance figures includes single data points for simple reference. Basically the trade is between trip time and initial mass in low Earth orbit (LEO). The power level establishes the reactor size requirement while specific impulse shows the performance level necessary to meet the flight time. The propellant mass is important in establishing the operational costs for launch as discussed later in Section 10.0. The curves are provided to give the the performance levels achieved and the reader a broad perspective of performance trends.

the initial vehicle mass versus flight flight

time, shows specific fusion reactor’s

Here we discuss realized expectations

of high to be within the domain of

Fig. 2.9, mission considered

from the use of fusion energy.

time and initial vehicle mass

that as exhibited

from high performance

power capability.

can be by the

space missions

the advantages

the significance

to the as

for manned

Reduced

performance

propulsion

systems,

impulse,

Benefits

energy

flight

2-29

time

and

(/)

t-”

°D

..=.,...,=,....

1000

10,000-

t- :E cE

j/,

oqo= 1 kW/kg

c_o= 10 kW/kg

2.0 High Energy Mission Applications

Using a propulsion NASA could perform a Manned Mars Mission with a total propellant,

the same point considered difference plant and a space bound propulsion

A more realistic performance designs (O_pl). For Tlie

round trip times as short as 160 days were calculated. of propellant

initial vehicle mass of 274 MT in LEO, and propulsion

is those propulsion that design, initial

2For brevity, system’s years unless otherwise

Initial vehicle mass variations with flight duration for a Manned Mars Mission.

and its trade would be to extend

is made for herein. between

In fact, missions significant generation

the (xpl/0.44 that a more practical

reactor power of 1 kW/kg

time of 110 days fuel, the payload,

the nomenclature CCpxx/YY is used in this report

round trip flight of inclusive

system designed with a specific

for all a most power

the propulsion in

flight duration of 210 MT. 2

the mission performance

alone commercial

parameter based

1,041 MT, and large

for early developmental

costs, would indicate

That an Earth

3 months each way,

681 MT, Fig. 2.10,

consumed, attendant

the round trip time flight

power of 10 kW/kg

the total reduction

having a specific

time [YY] nominally

system designs

vehicle mass,

[xx] and secondly

to designate first

Flight time, years

system/vehicle

space fusion

trip mission,

to 6 months,

specific power

distinguishes

a propellant

parameters

to achieve

(COp.10),

electrical

quantity

system.

Fig. 2.9.

mass.

round

noted.

large

2-30

goal

for

1”1

’.

10000

(zp = 1 kW/kg

ocp — 10 kW/kg

ocp— 0.067 kW/kg

2.0 High Energy Mission Applications

A reduction in flight time increases the propellant demands from 335 MT to 681 MT, i.e., we pay a 100 % propellant mass (increase) penalty for a 12% reduction in flight

One important point to be made here is that “propellant mass” is defined as the sum of the reacting fuel mass plus the mass of the diluent, assumed to be

time of only 11 days during a 3-month one-way flight

Propellant mass variations with flight duration for a Manned Mars Mission.

hydrogen. reactor) For example, element.

system uses $3B in launch

be a better be compatible

system trade plasma with

vehicle oxygen use

30 MT That would

with of heavier

consumes 335 MT.

the launches,

has to be studied

the OCpol system

the high specific

Flight Time, years

Cost benefits

density may

it also provides

be considered.

from reducing

the propellant

launch-to-orbit

could not

of propellant

thermalization

approximately

of propellant

optimization,

its superior

A half-year

10 Shuttle

efficiencies

substantial

propulsion

Fig. 2.10.

the flight

Not only

elements

For for

benefits.

whereas

burning.

reasons

trip for

savings

time.

(mixing

subject

further.

system

reduce

in the

power

costs.

mass

other

does

time,

save

That

2-31

o_pl

cost

The

can

just

but

.1:’

the

effort

case,

fusion

power

better,

airlines

bracket

specific

compare

efficiency

the_eturn

of space

comprises

consumed

so shorter

to become

efficiencies.

the relative

to maximize

are a must.

cost effective

developmental

the propellant

in the pursuit

For spacecraft

and operational

that of commercial

If we are ultimately

of between

upon the availability

an index in the

the airline standards

Payload efficiency

flying ao_D1 o system,

efficiencies for

(~50%), which provides

trip mass at the end of

and the round trip flight

72% of These two

vehicle mass and 73-% of

is the best the

mission. the outbound

of high payload mass fractions.

2.0 High Energy Mission Applications

conduct efficiencies, depends

is asymptotic the achievement

propulsion. .-1 and 0.10.

would time would require

of space operations, preferably

for payload The commercialization

increases the payload comprises

be 650 MT of krypton, nearly two years.

As an example, Payload system,

the payload the end of mission mass.

. for the 6-month m_smons. For a _“1

In the Ctp0.067 xenon, or argon, This curve without inert weight or tremendous

Considerable investment payload dramattcally 22% of the initial vehicle mass and 30% of

for a 6 month m_ssion - 90 km/sec. km/sec, maximum of almost 43 km/sec. elapsed times are made possible

See Fig. 2.11. by the higher velocities.

at this time, of significant expenditures

cannot in the propulsion

be anticipated system’s

C)-early the shorter mission

the delta velocity, was 130

reductions in propellant.

The CtDoo67 mission’s

For the c_.,,#130

Higher Av

day mission,

the energy

Av was a

flights

input,

2-32

i e,

_,#IV

”

_’,

’”,_

100

300-

…

NEP MAX

p = 10 limit

c_p = 1 limit

Specific power = 1.0 kW/kg

…,_… Specific power = 10 kW/kg

2.0 High Energy Mission Applications

-.-® … Specific power = 0.067 kW/kg

Fig. 2.11. Vehicle velocity variations with flight duration for a Manned Mars Mission.

not be difficult in Section

should discussed

Mission achieve,

Flight time, years

to accomplish

this Manned

considerations

requirements

Performance

performance

(Fig. 2.12)

“Theoretical

Capability.”

the fusion

propulsion

theoretical

to 5.0

potential

systems

average

impulse

specific

based

using

upon

Mars

2-33

The

the

“O

…

”

Q. E

Q. O3

…

._o

j,°,,.°,°o.Ol,.,,

°,,,,,.o°,O,°°,o

”__

j°.=°°=°,_,,,,°,.o

.o°‘p’°_''''°”°.'''°°”

10 3

10 5.

10 6.

10 4 *

Q ¢0 _5

Applications

o.p = 10 kW/kg

ct,p = 1 kW/kg_f,,..

’"" …

2.0 High Energy Mission

mnnJmum to 12,900 particular required enhancement 35,766 specific is a consequence target more propellant,

(Zp0.067 system to deliver an initial system design. designed. the 0.3 to 0.7 N thrust duration.

for ion engine to be have as less than 5000 hours in the burn over

this is flow The the That the at and more to thrust

for a (z.,/0.44 mission an average Isp of 9,440 seconds (4,450

specific This permits the acceleration

required. Notice that systems. Arrival

time-more massive trajectory.

requirement is higher of

seconds Only an average

the expenditure vehicle,

for the o_._,, mission is attainable

for the longer a constant

the 0c..1/0.5 p, opportunity

vehicle mass of 1,004 MT.

of 9 x 10 -4 m/s 2 is doubtful

a significant rates

The life limit at the present

flight acceleration

mission. for attaining

acceleration That

of greater therefore,

To provide the higher

for xenon and argon.

Similarly considered

maintain is reduced.

mission. for

hour burn duration

for a Manned Mars Mission.

being the average

power a higher

ion engine would

seconds mass

seconds impulse

of 4,174 seconds

flying requires

The curve shows

a more massive

a 900 N thrust

to be possible

accomplishing

the capability

is considered

ap = 0.067 kW/kg

the average

for O_po067,

acceleration.

value of

is optimal

a constant

of 10,606

maximum)

A 17,000

However,

a vehicle

requires

is the

time, years

impulse

specific

with flight

Fig. 2.12.

quickly

range,

thrust,

variations

hence

thrust

duration

Specific

impulse

2-34

and,

that

Flight

for

0.1

ijnk/

_JU

IJ/

flight

(ICF)

power

These

by the

for for

the flight

1,040 N.

a manned

parameters

just under

The actual

is required.

the heavier

Interplanetary

thrust are

to accomplish

then returned

(Zpl to be

time, a period

these missions

hereirl, because

Space Transport

and 178 MW for

reactor, designated

least as established

time, a the 100

the (_.,,J0.5 mission.

ten days, propulsion

H_u The average

for anticipated

time NASA is developing

At as SP-100.

is the Inertial Confinement

Fusion Applications)

2.0 High Energy Mission Applications

to account is 2,400 N,

two years level becomes

be larger vehicle achievable.

is 93 MW for the reactor will

… inefficiencies. the _pl0,

flight large. the present

time becomes The fission flight

too long. To achieve a 1.93 year

design concept The VISTA (Vehicle for

The fusion jet power necessary 0_,/0.5 mission

Manned Mars is not a good mission for O_p0 067, at mission mass and energy asymptotic at space reactor power 650 MW reactor kW fission

An optional approach. study referred Mars (Ort87). the crew to stay there for mission duration. consumes repetition initial vehicle mass was 6,000 MT; MT. The propulsion 104 MW. Aview of VISTA is shown in Fig. 2.13.

to earlier used an ICF system for performing That design carried a 100 MT payload to the Red Planet, allowed to Earth for a 100 day total and a target gain of 1,500 and pulse 2x105 N. The carried was 4,400 jet power, 2.0 x

20 MT of The study assumed rate of 30 Hz. This was a high thrust engine, producing

system Isp was 17,000 seconds

system is designed

The tritium.

to burn D-T

of propellant

the quantity

and total

2-35

Final

Landers

modules

_ellant tanks

Applications

laser mirrors

% % B

2.0 High Energy Mission

Just as the mining of materials is key for the habitat fabrication for settlement of Mars, so too will become propellant manufacturing can be anticipated to become an important element the space mission architecture. Martian a planet manufactured propellants can be used either for the transport of vehicles back to Earth or toward the outer parts of the solar system, where launch vehicles can platform to the outer planets serve as a more efficient, scientific a major than

of propellants In-situ in Production of propellants on Mars makes use of

attests The size of for intended applications. and 100 MT return payload) outbound

the initial mass in LEO is 280 MT of 125

high thrust (100 days) whereas days.

statements A performance the two systems,

ICF, was made: assuming for %1,

(100 MT low thrust MCF and

for the processing space

the spacecraft large power

the Mo is 6,000 MT for a total

the mining of materials

ICF powered manned Mars

fusion is currently

Pellet firing 7 position

time expedient

EXPLORATION

flight duration

an essential

as a space

for efficient

EFFICIENCY

from Earth.

and space

Magnet coil and shield

IN OUTER

operations.

technology

comparison

operations

to earlier

resource

launched

PLANET

an %10,

vehicles

become

center.

GAINS

spacecraft.

2.2.1.1

Fig. 2.13.

launch

(VISTA).

could

Mars

2-36

that

80 m

the

least

of at

costs.

earlier.

reduce

vehicle

Hence,

number

program

when a

the cost

their size

as part of

the ultimate

and specific

of operations

the chemical

is the use of

as mentioned

lunar volatiles

in the overall

in the launch

become equipment,

significantly operational

approach of Helium-3

power dramatically.

is necessary impulse

as a large mass component

fusion fuels, where the fuel

2.0 High Energy Mission Applications

for a quicker, If established

of to achieve fuels

vehicle cost, launch equipment,

outpost planets. architecture, activities.

the time to accomplish and even _

on Earth are by themselves effects

the outer the space mission future space

as a by-product of when one considers

ultimately support is a key parameter

for exploration depot a gain in the economy

the costs, propellant in terms of sizing a

equation, parameter In the final cost equation,

cheaper means as a propellant a Mars depot could provide

Another mining propellants cascading nevertheless, vehicles, vehicle’s

propellants/fuels, impact costs, ground greater High specific requirements

produced While insignificant, cost a very significant plus logistics.

of a launch system, missions, flight, particularly the same end objective. propellant

desire the same benefits now enjoyed by the industrialized example, consumes the world’s two Those development, skyrocketing Perhaps have functions the local planetary

The US, the energy. third world for energy, lack of availability. by then, energy will the very basic for and warmth. While utilization of here are not being suggested

Looking into the not too distant the time frame of relative current variables: reduced variables According population

life here on Earth, such as in the in the by the two

a that both value. Earth’s the land

to rapidly and creating those global problems that life on Earth, namely, resources

For other material that advantageous. This return trip’s propellants

requirement for deuterium up along over being transported

this problem, could well extend man’s ability to conduct

to explore Any bulky, massive cost/performance

will combine prices energy if some of

cost ratio that we now enjoy.

the way the current to LEO and out

serve to one is mathematically

in well under a century. is a natural

it will be consumed food, shelter,

requiring to the designation.

nations. 25% of and thirst

ratio of energy recently

to product the to cover

a corresponding are not

growth an insatiable

extraterrestrial can

as a means resources

to increase demographic

space exploration without

to the cost of consumer

to improve countries

sources be picked

continue developed

just several decades,

at Mars and beyond

resolved only

the cost model

will regulated

is very approach

future for projecting

at a rate sufficient

mass increase,

As communications

and an increased

one can seriously

question whether

and two things

It is quite clear

energy will

are ultimately

and demand,

extraterrestrial

so precious

is preferred

are certain

assumption

to happen

the space

the lesser

demanding

to resolve

developed,

and 3He.

of energy

population

increasing

incentives

demand.

and will

products

is large,

escalate

possibly

become

factors,

4% of

energy

remain

supply

Costs

those

exist

2-37

with

that

the

for

2.2.2

MARS

means

received

the first

technical

demands

BEYOND

MANNED

necessary

so, trip.

MISSIONS

the Martian

This mission

two decades

and not energy

Mission Description

since it has not yet

outer planetary missions.

The bottom line is that

consideration, a very ambitious,

2.0 HighEnergyMissionApplications

trip is already no transportation render

since There is currently High energy

this mission category, almost system.

the chemical and the NERVA fission ago as not being

for accomplishing incapable systems system propulsion to the space

exacerbating the Earth’s energy supply situation. alternative energy sources are needed for space’s future.

Some thought was given to manned category is being introduced surprisingly demanding such missions. of performing was shelved transportation

Obviously the moons environment appears weaker manned considered. environment degree standpoint risk. Galactic spacecraft radiation. radiation also provide

radiation and Pluto hold some from the of the hazard source from another

or not man could safely explore radiation the severe Neither belt

is to Earth’s Van Allen belt, the outer moons might be cosmic

A massive distance time using an initial of 23,600 impulse power of 1 kW/kg,

into consideration and to a lesser degree, Saturn. At Saturn

the asteroid and potentially more rewarding missions

due to the long trip times, causing Sporadic

seconds. returns to LEO a 60 MT payload.

at a separation round trip flight specific a specific

those associated likely for missions

at Saturn is improbable exposure

vehicle mass of 460 MT, with a mission

is still comparable although

hazard to the crew in those missions.

of 1 AU each could be accomplished

than at Jupiter; exploration

to those levels. Uranus, Neptune,

a high degree of

one additional comprises

belt could also be accomplished

The extended is additive

significant temperatures

taking with Jupiter,

rays can activate materials

is not known to possess

of promise that

used in the construction

the crew to the natural

to the inner moons.

the more interesting

in 2.25 years total

The low planetary

Manned of

150 MT payload

of those bodies.

planet manned

for exploration.

design, which

for exploration

That mission

an interesting

to 3 separate

due to solar

the radiation

but since it

explorations,

and is one

transported

exploration

is whether

for outer

challenge

asteroids

assumes

radiation

A_teroid

average

planets,

thought

present

cosmic

flares

least

2-38

the

belt

that

over

time.

could

Uranus

Pluto

Applications

payload

payload,

Ne0tune

seconds;

i.e., 133

planetary

radiation.

that man

accomplish

is probably

is 1.5 GW.

the specific

is 620 MT;

An exploration

trip to Miranda,

to 5 years total

round trip flight

If only a specific

2.0 High Energy Mission

61 MT inbound

Asteroid generated

Using the same vehicle

the time to Triton and return is

the first planetary mission beyond

power propulsion impulse

without concern for this mission as Mars,

less than 5 years for 1 kW/kg and ~2.5 years for 10 kW/kg.

round trip flight The initial and the jet the trip

An identical mass used for this flight showed slightly

MT outbound time is 2 years for a specific vehicle mass power time will be lengthened

the mission system of 10 kW/kg. is 65,400 power system of 1 kW/kg is available,

Comets dynamics Man could serve to perform focused geologic

MT return over 5 years with a 1 kW/kg system and ~3.5 years for a 10

for comet missions which the end of at discussed to

due to the the sun. of the more attractive comet samples.

Mission can be studied 2.0. Section raise plants, desirable,

activity the recommended long manned trips, we can expect

expected can be reduced by launching

The outermost payload kW/kg system.

lights for plant growth. perhaps

simply when in the presence

a great involved with comets

If that approach of a fusion

and for the retrieval of specifically

Transportation from Mars.

by a 133 MT outbound/61

the use of hydroponics

of selected

were not calculated

in-situ examination

can be reached

and the use of

to be required.

requirements

for manned

oerformance

performance

as part of

capabilities

is deemed

exploration

particularly

and flight

significant

demands,

in slightly

can be

features

analysis

Comets

Mission

present

interest

energy

planet

scale,

2-39

time

For

Applications

a high energy

and interstellar

2.0 High Energy Mission

II. SPACE SCIENCE MISSIONS

two mission classes:

space science missions,

is uniquely mission enabling. We can consider

For the far outer planets capability

I IAsoLA_sYSTEMSO,ENC,

time span; science experiments exploration

I. Space Science Mission Objectives:

of the major solar system science

-Temperatures -Climate

system can be accomplished

-Atmospheric -Pressures

IB, INTERSTELLAR SCIENCE MISSIONS

space can be performed.

relatively destination;

flows of surface matter

The list below provides

-Search for organics

BEYOND THE SOLAR SYSTEM

history: meteor

can be quickly

of the planet’s

Solar System

-Soil motions

and scientific

-Composition

a summary

transported

exploration

and water

objectives:

interstellar

-Structure

the solar

-Geologic

Scientific

missions

impacts,

-Winds

interior

to its

short

2-40

in a

dust

fields

-Surface

radiation

-Science

elements

changes.

-Magnetic

-Mapping:

objectives

by which

-Seasonal

of subsoil

-Soil age

exposures

distributions

and compounds

and gravitational

from the surface

can be achieved

-Density/composition

is by the following

-Solar wind plasma

-Imaging of surfaces

long term high and low level

at altitude and locally directly

2.0 High Energy Mission Applications

these Infrastructure:

The means Space Science

*surface of planets *asteroidal

A. Scientific Outposts -Orbiter

The propulsion the high energy planets, missions demands sources returned. frequency. window to open, we could realize by the use of spacecraft

to the outer These since the kinetic energy energy science launch launch launch windows

are essentially are even greater increase with distance increases

reduce the impact on program costs. importance

to high specific of the space in spacecraft gravity-assisted

surface B. Science Return vehicles

from the Earth. Access and quality the quantity

launch windows will is of greater

Expanded to launch windows

the improvements the next available

as for Manned Mars Missions.

For example, Rather

the same beneficiaries

to the high energy missions.

technology of

the type envisioned

Mission DescriDtion

launches with

science missions

for accomplishing

within expanded

AND MOONS

of high energy

and electrical

rover vehicle

than waiting

-Soil sample

-Atmospheric

requirements

UNMANNED

substantially

-Permanent

PLANETS

laboratory

Tolerance

of power

designed

samples.

-Surface

consider

for Av.

a large

OUTER

-Lander

reserve

herein

power

2.2.3

2-41

craft

for

2.0 HighEnergyMissionApplications

Scientific instruments remaining in orbit or on the surfaces of planetary moons are important for synoptic data gathering purposes such as for monitoring the body’s physical characteristics of winds, temperature, pressures, and solar wind plasmas. Remote soil analyses for chemical composition determinations are also of interest.

These science missions can be accommodated in a manner similar to the Manned Mars Mission scenarios discussed in Section 2.2.1. Mars is not included below since the precursor, premanned science exploration missions are presently envisioned as being required too early for the presence of high energy systems. The Manned Mars Mission is assumed to provide for the subsequent Mars science program activities. If the desire exists to use this system for Mars sample return missions, then a specific power system of 1 kW/kg would deliver the 20 MT outbound-10 MT inbound payload in 0.6 years using one Shuttle payload of fuel (27 MT). For a 10 kW/kg system, the same mission could be accomplished in ~3 months. As missions extend further out, however, high energy assumes an ever increasing importance. Depicted below is the scope of solar system science missions considered.

The benefits of higher specific arrives its comprehensive, the on-site instruments

telemetry data are able to serve for longer mission durations.

power are: more reliability

instrumentation carries

instruments; and

of science bit

destination increased

package a more

the package

quickly; payload

the science

a higher

transmits

I SOLAR SYSTEM SCIENCE:

stream;

vehicle

station

- $CI[NCE OLflPO\$ 1S

-SAMPLE RE1URNS

2-42

NO1 EXAMINED

ASTE ROIDS

the

NEPTUNE

COMETS

URANUS

JUPITER

SATURN

SOLAR

VENUS

PLUTO

the

there

offers

exists

of soil

unique

physics

to study

Consider

providing

radiation.

exposure

Amalthea,

a greater,

of energy,

Saturn

to each of

the effects

that deploy

of extended

is to monitor

an opportunity

The differential

for establishing

can be achieved

and A rover

by similar missions

effects of decreases

their unit cost while

probes, more probes

to study the changes

close up and to examine

launch, per on science.

rendezvous, in order

opportunity of materials.

exposure from Jupiter

the unique to a variety

2.0 High Energy Mission Applications

The proposal samples

of very long term high energy

mission radiation emissions

are in the planet as

could be carried return

quicker a large consumer

With high energy, science. materials

and to provide time to study other solar system phenomenon.

Samples would be returned in the intensity

to perform some the closest moon of Jupiter.

planetary to the fly-by missions advance

the effects to Earth for further analysis. level of environmental the moons.

For spacecraft lowering Missions which permit preferred seasons

Production) aircraft payload mass was -6.5 MT, 0.21 MT of which was allocated aircraft. planetary

Rendezvous would for comparative Uranus those ring compositions asteroid missions are discussed

The total for a solar powered the use of the flight

rings through can be studied payload not available

a new mission, with the rings of A comparison of The interest.

Probes by “aircraft” the are an

Solar energy would not be an option at Uranus,

a new missions with the

since this has not been considered

with the rings and a ring sample

Rendezvous mission, would

that would map the atmosphere

with Uranus’s be of great

in the ISPP (In-situ Propellant

composition with asteroids

Payload mass determinations

would also be of great

using dimensions.

as well as rendezvous

and possibly mapped

can be characterized

the use of on-board

and a ring sample

can be anticipated

rings interest,

SAIC examined

return mission,

for comparative

the atmosphere

future mission.

and exploration

return mission,

to be massive.

or alternatively

as a possible

for propellant

and surface

the mission

the planet’s

composition

atmosphere

is feasible,

hold great

of Saturn

propellant

purposes.

for Mars

analytical

supplies.

requiring

missions

“aircraft”

interest,

Uranus

earlier.

Titan’s

Study.

in all

some

three

later.

2-43

type

their

from

data,

rover

similar

overall

Pluto’s

permits

provide

surface

Pluto

science

benefits

NeDtune

structural

regarding

on Triton.

uncertainty.

to conduct

topography,

composition

data would

configuration

and surface

This mission

characteristics.

With origin,

return mission

etc.), presence

has an orbiter

the spacecraft’s

physical magnetic

exploration missions

2.0 High Energy Mission Applications

the planet’s temperatures,

soil analysis properties, fields,

A robotic An orbiter will the

impacts, regarding can be drawn

holds a significant can be contemplated. on Earth. the

trajectory which currently fly-by and rendezvous, detailed

of new the i.e., capture or formed from primordial matter

Observations improved mass determinations Two Plutonian missions, sample characterize atmosphere, (roundness, mass concentrations, information moons, and conclusions aforementioned from a gravitational it resulted whether in the solar system.

Mission which sample in comparison return missions Saturn’s the round trip time for carrying return respectively.

during and provides time elapsed Five round trip sample Europa, to: Jupiter’s Plots of of 20 MT and a 10 MT five moons

The payload masses were as previously technique

calculations orbits returns are possible

A parking orbit of 670,987 For this mission’s

was 4.2 AU from Earth. the mission

assumed indicated. were unchanged

This is a massive moon which is 1.6 times the distance

Consider calculated was 295days.

The initial vehicle mass of 92 MT (Fig. 2.14),

with that provided examined

the atmosphere, shortened mission

show that science probes

the target, on a substantially

km from Jupiter performance

Titan, Uranus’ Miranda, Neptune’s

Jupiter. this spacecraft.

performance the spacecraft

from the Martian calculations.

Triton, and Pluto’s Charon.

the Jupiter mean distance

by current which

Io from the center of

first a _plo-powered

outpost missions

input parameters

round trip flight

and calculation

the destination

The shortest

an outbound

oerformance

are shown

technology.

spacecraft.

Otherwise,

comprised

in Figs.

to 2.33

included

analysis

payload

Mission

Europa

data,

each

were

2-44

2.14

trips

time

for

…

I—

¢,0 t_

Fig. 2.14.

_p = 1 kW/kg

Flight Time, years

(zp— 0.067 kW/kg

Europa sample return mission,

2.0 High Energy Mission Applications

Europa sample return mission, propellant mass variations with flight duration.

initial vehicle mass variations with flight duration.

mass of 50 MT (Fig. 2.15),

(zp = 0.067 kW/kg

Flight Time, years

o_p=,10 kW/kg

(zp = 1 kW/kg

a propellant

Fig. 2.15.

carrying

.o o.

2-45

1oo

1000

w *|

1—

1:3

1oo

300-

""O’°’

NEP limit

Applications

or.p = 1 limit

o_p= 10 limit

Specific Power = 10

2.0 High Energy Mission

Specific Power = 0.067 Specific Power = 1

provides a Av of 352 km/s (Fig. 2.16),

with flight duration.

0qo= 0.067 kW/kg

Flight Time, years

and requires

return mission,

(Fig. 2.17).

an average

(zp : 1 kW/kg

of 42,205

(zp : 10 kW

with flight

Fig. 2.16.

Fig. 2.17.

seconds

impulse

variations

specific

duration.

lO4.

impulse

velocity

specific

Europa

sample

…

2-46

” _’°

10 6*

10 5.

“1

…

10 3

”|

1’

”

life).

flight

likely

thrust

specific

mission

scenario

requiring

decrease

the flight

the upper

is 57 MW.

The lower

significantly

an average

requirement

approaching

The average

the jet power

in an increase

for a 6.2 year

is an averaged

is to drastically

to accommodate

of system,

increase power

thrust required

but at a significant

the initial _1,

a 420 MT propellant

the mass impulse.

time by only 47 days.

initial mass is asymptotic

limit of e_Do067 systems

impulse of 14,724 seconds.

1920 N for a _pl/1.56 mission;

2.0 High Energy Mission Applications

to 843 MT (l_g. is imparted

increase The Av (Fig. 2.17)

A more propellant resulting increases

the mass, it to 240 MT,

requirements The initial vehicle mass

at ~4.62 years: Mo = 1,037 A six year mission

time of 22 days. Decreasing The engine

acceptable flow rate sufficiently in total

increase round trip mission Isp is 7,709 seconds,

of Mo to 976 MT and a propellant than the ec.,,_ design.

the data show an order of magnitude specific the o_pl 0 design.

For the O_pl design, vehicle mass over requires an increase 2.16), a factor of 17 greater 223 km/s,

The O_po067 spacecraft’s MT, Mp = 900 MT, Av = 96 km/s, <lsp> = 6,304 seconds. lowers specific 240 MT. The propellant mass is 173 MT and average value thruster the fission reactor While this mission orders researched.

to study the This, effects of extended radiation exposure to materials. laboratory for researching materials which have been exposed to the high and low Jovian radiation lies within the most severe part of Jupiter’s radiation belt. The purpose of the sample return mission to investigate the physics of materials after exposure to high and is, therefore, The prime source of low fluxes of particles over very long duration exposures. data from of >1 MeV several electrons and protons were measured at 108/cm2/s. Measurements were made at 0.1, 3, and 21 MeV (electrons) and at 1, 20, and 80 MeV (protons) energy

in is a of trip; round trip mission.

the closest moon of Jupiter, provides a unique opportunity It is a natural

less than two years using (Xp = 1.0 kW/kg, Isp = 21,140 seconds.

power can theoretically greater level

the completion 6 N to 767 N for the shorter

rangedfrom is 7.8 MW for a 5.4 year

1 and 2 as obtained fluxes

The 20/10 MT Amalthea payload sample

power now being than current

jet power = 22 MW, Mo = 93 MT, and

return mission can be performed in

be accomplished, the

levels for millions of years.

is 1 to 2 orders of magnitude

levels characterized

10 and 11 and Voyagers

is from Pioneers

not been well

reactor higher

At Amalthea’s

of magnitude

2-5, Div83).

instruments.

at this time.

the reactor

Amalthea’s

ion fluxes

technology.

The thrust

Amalthe_

on-board

altitude,

largest

heavy

space

(Figs.

have

orbit

2-47

is 2

than

The

(at

C/)

for

the

this

was

This

lOO.

initial

twice

mass

used.

moon

years,

lOOO-

results

almost

having

vehicle

sample

surface

interest

in Figs.

to 2.21.

for many

Titan

of Saturn,

the mass

particularly

unexplored

A The

and (xpl 0

of 1,221,855

are displayed

its atmosphere.

return mission

ocp= 10 kW/kg \

the calculations

of Earth’s moon,

scientific orbit

the Ot.po.o67, _pl,

km from Saturn’s

2.18 spacecraft

Consider in Fig. 2.18.

2.0 High Energy Mission Applications

has held great parking target

o.o,Tkw o

!i k-”

For a 1.2 year mission, mass of 56 MT (Fig. 2.19),

initial of 100 MT, a propellant

initial vehicle mass variations with flight duration.

Fig. 2.18. Titan sample return mission,

reasonable initial mass

mass accomplish

A (xpl 0 a using

The propulsion

_p0 067 spacecraft

8 years. a year

Flight Time, years

at approximately

is asymptotic

the mission

a vehicle

in less

system

vehicle

having

mass.

2-48

than

can

…

10-

’

-1

10 3

10 2

10 0

O.p=

; o_p= 0.067 kW/kg

\ o_p= 1 kW/kg

2.0 High Energy Mission Applications

Titan sample return mission, propellant mass variations with mission duration.

Titan sample return mission, specific impulse variations with flight duration.

and a propulsion seconds

system producing

Flight Time, years

an average

(Fig. 2.20)

of 50,650

Fig. 2.19.

Fig. 2.20.

impulse

specific

Flight Time,

2-49

…

¢n —‘t Q.

years

10 3

10 4

10 5

10 6

t,,) G)

o.) a

will

impart

NEP MAX

Applications

0_ p = 1 limit

o_ p = 10 limit

2.0 High Energy Mission

to the payload a Av of 437 km/s (Fig. 2.21).

Specific Power = 0.067 Specific Power = 1 Specific Power

This mission was targeted 18.18 AU from the Earth. are shown in Figs. 2.22 to 2.25. The round trip mission is accomplished

trade; sample from a vehicle whose initial mass is 74 MT. The average is 18 MW.

the vehicle and propellant masses specific conceived, life of 7 years.

For an initial engine yielding 104 km/s. which reduces But NEP limits researched

requires and an is flight to 90 and 49 MT. the

For O_pl , a 3-year MT are consumed is 26,202 seconds. places a low thrust

(average) reasonable mission mass-wise

vehicle mass of 990 MT, 6,889 seconds

a 6.7 year mission 856 MT of propellant,

years, using a specific of 112 MT (Fig. 2.22).

system of o_pl o, an initial vehicle mass

The Av imparted be a 10 year

impulse. would respectively

return flight offers a reasonable

is beyond the currently

to a parking Results

as currently reactor’s

on the engine — 220 N.

the O_pO067 specific

light mass mission

as well as being

from the mission

km at a distance

power propulsion

orbit of 129,886

the mission

Flight Time, years

performance

The power

requirement

calculations

of 10,221

return mission,

propellant

averaged

Miran_la,

including

seconds

A more

required

system,

impulse

in 1.93

specific

beyond

Isp

with flight

Fig. 2.21.

variations

duration.

velocity

sample

level

2-50

This

Titan

I—

o_ t-

’,.

100

Or.p= 1 kW/kg

C_p= 10 kW./kg

(xp — 0.067 kW/kg

2.0 High Energy Mission Applications

,o 1”

Miranda sample return mission, propellant mass variations with flight duration.

initial vehicle mass variations with flight duration.

Miranda sample return mission,

of 66 MT (Fig. 2.23),

o_p= 0.067kW/kg\

Flight Time, years

a propellant

,,.,,

Fig. 2.22.

Fig. 2.23.

10 kW/kg

-,,

1000!

2-51

mass

100-.

o_p

1_)

…

“E

Q..

I—

Q.)

o (_) (/’)

lO 6

J""_”

specific

impulse

seconds

co 104.

of 63,303

(Fig. 2.24).

Ocp= 1 kW/kg

o_p = 10 kW/kg

and an average

2.0 High Energy Mission Applications

Miranda sample return mission, specific impulse variations with flight duration.

22,858 years MT (Fig. 2.24).

/ ocp = 0.067 kW/kg

of 809 MT, 687 MT of propellant,

35 N, and the Av is 172 km/sec

than requirements,

trip and average

to 7.8 to 687 is a

The initial mass

is 6.2 MW versus

8.9 MT compared

Flight Time, years

using impulse

The jet power

slightly lower

in substantially

e_pl powered

(Fig. 2.25).

The thrust

101 MW.

completes

Fig. 2.24.

seconds.

a round

doubling

specific

modest

vehicle

in 3.5

results

an of

years

Note

flight

level

2-52

time

that

fuel

the

…

.,,.,

loo

p = 1 limit

NEP MAX

(z p = 10 limit

2.0 High Energy Mission Applications

Specific Power : 0.067 Specific Power = 1 Specific Power = 10

The O_p0.067 vehicle an average specific required demonstrated

Miranda sample return mission, velocity variations with flight duration.

this mission of 77 MT (Fig. 2.26),

the mass orbital for a science

This massive The sample km at 29.06

about twice for a parking curves

return mission AU from Earth.

is on the order length

The divergences variations

of 108 seconds of mission

contains was targeted

initial demonstrates

significantly. years when

(zpl o system accomplishes

a 1,033 MT initial mass

moon. of 354,681

are shown flight and

duration for NEP.

The designedto

is a 10.7 impulse

and The

life

to only the

in Figs. time

Flight Time, years

in a reasonable

the maximum.

vehicle mass

year mission,

2.26 through

moon mass

requirements

Performance

more 2.87

on mission

of Neptune

the SP100

expectancy

importance

of Earth’s

exceeding

parameter

Fig. 2.25.

compared

by about

of 8,836

and the

an initial

seconds,

exceeds

duration

specific

altitude

to this

vehicle

reactor

vehicle

effects

fission

Triton

power

moon

using

59%.

2.29.

even

firing

2-53

This

due

that

the

F I-

I ,

—

| ! I

100

10000 =

Applications

0q:) = 0.067 kW/kg

2.0 High Energy Mission

propellant mass of 39 MT (Fig. 2.27),

vehicle mass variations

return mission,

Flight Time,

with flight

Fig. 2.26.

duration.

sample

2-54

Triton

years

initial

1—

e n

1000

10000_

Ocp= 1 kW/kg

O_p= 10 kW/kg

Or.p= 0.067 kW/kg !

2.0 High Energy Mission Applications

and average specific impulse of 79,815 seconds (Fig* 2.28).

Triton sample return mission, propellant mass variations with flight duration.

Flight Time, years

Fig. 2.27.

2-55

10 4.

10 6 ,

10 3 *

E .__

’/'''''

(_ 10 (./3

(_p— 1 kW/kg

(zp — 10 kW/kg

o.o67kw/,g

2.0 High Energy Mission Applications

without shown by the even greater the propulsion severe. 4.6 year

The vehicle round trip mission, Fig. 2.29.

Fig. 2.28. Triton sample return mission, specific impulse variations with flight duration.

rise shown for the O_po067 specificpower

penalty to 393 km/s for

or as If is very the

is limited to O_pl, thi_ propellant

and the time could be reduced

from the high rate of mass

is less initial mass

rapid rise rate of

the (_pl design

system design

kinetic energy

Flight Time, years

requirements

The flight

increased

sensitive,

impact

further

value.

2-56

…

1;)

>”

t21

tO (D (,O

600

*—Q—

(zp = 1 limit

(zp = 10 limit

(zp = NEP limit

Specific Power = 1

Specific Power— 10

Specific Power = 0.067

2.0 High Energy Mission Applications

For O_p0.067 to accomplish MT, propellant seconds over limitations, value. current 7-year

TABLE 2-1. Comparison of specific power performances for a round trip Triton sample return, 4.6-year mission.

vehicle mass of 9,800 of 8,818 impulse impulse the

a limit of 14 years occurs too, be noted here,

Fig. 2.29. Triton sample return mission, velocity variations with flight duration.

Based upon specific specific

mass of 9,383 MT, and averaged

Table 2-1 below compares

Maximum Isp, seconds

Minimum Isp, seconds

life by a factor of 2.

a 13-year mission,

fission reactor

Flight Time, years

times exceed

are required.

_ at_12.7 years

the mission

Ctp, Mp, MT

the 10,000

two equal

long flight

time trips.

an initial

It should

at that

duration

impulse

specific

Av, km/s

second

F, Nxl03

114,730

Mo, MT

Pj, MW

43,750

87,400

these

kW/kg

flight

5,770

0.067

1.000

10.00

1,031

2-57

895

393

its

will

the

has

and

was

also

2.33

2.76

2.30

With

Figs.

been

data.

Pluto

mass

some

being

offers

target

round

There

years.

regard

17,233

vehicle

system

in only

design,

Charon

surface

through

greater;

smaller,

Charon

recently

targeted

illustrate

to have

but with

to those

relaxation

of with

be great

propulsion

in energy

for Triton,

determined

the planet

capabilities.

are similar

To do so,

requirements

the physical

trip mission

the distance

this mission

are of great

to the solar

at a distance

target mass

Characterization

The mission’s

an atmosphere.

that atmosphere

be accomplished

km from Pluto’s

a O_pl 0 propulsion

interest system’s

237 MT (Fig. 2.30);

properties and

the the initial

of Charon relation

of 38.44 AU from Earth.

development capture

requirements. can

in planetary altitude

interest at a parking

2.0 High Energy Mission Applications

evolution. In this mission

and of to understanding

initial vehicle mass variations with flight duration.

Charon sample return mission,

is 171 MT (Fig. 2.31 );

(xp — 0.067 kW/kg

Flight Time, years

the propellant

ocp = 1 kW/kg

Fig. 2.30.

10000-

mass

2-58

I |

(,/} (13

F-

lO,

100-

years

10000-

sample

Charon

Fig. 2.31.

Applications

Flight Time,

ap — 1 kW/kg

return mission,

(xp = 10 kW/kg

o_p = 0.067 kW/kg

2.0 High Energy Mission

is 464 MW, and the mission

require 5.5 years to complete

impulse is 70,134 seconds

3,320 N. A o_pl propulsion

and the average

with flight duration.

(xp = 0.067 kW/kg

system will

The power

(Fig. 2.32).

requirement

mass variations

(xp — 10 kW/kg

the round

return mission,

(xp = 1 kW/kg_

averaged

Flight Time,

specific

Fig. 2.32.

propellant

variations

thrust

impulse

o _10

specific

Charon

sample

level

2-59

years

cLlO

10 6

10 3

f_"""

.__

O. E

800-

mass

1000 -

6oo

vehicle

seconds.

an initial

a system

of 28,568

of 676 MT,

vehicle mass

using impulse

of 797 MT, propellant

O_jp= 10 limitp = 1 limit

trip mission, and specific

2.0 High Energy Mission Applications

an C_pO067 has (Fig. 2.33).

flown with the Av of 170 km/sec

By comparison, 10,247 MT to provide

Specific Power = 0.067 Specific Power = 1 Specific Power = 10

Fig. 2.33. Charon sample return mission, velocity variations with flight duration.

“lb Flight Time, years

Three the asteroids,

to naturally is the amino

investigations comets.

and fruitful gas

not an NEP mission.

for pure scientific

contain acid’s

exciting of

of extraterrestrial

shown What

time is 14.81

The mission

us on Mars.

and Triton),

ASTEROIDS

constituents

requirement

to surprise

Description

The solar

has been

are The

the most

molecules

assuming

COMETS

subtleties

discovery

averaged

obviously

in some

seconds;

is 9,385

scientific

the trip

possible

greatest

building

impulse

Mission

specific

organic

resides

system

remain

moons

origin?

bodies

years,

amino

giants

inside

acids,

(Titan

areas

these

basic

2.2.4

hope

solar

AND

2-60

and

that

life.

the

for

been

gains

flights

planet,

energy

instead

Mission

system.

as the

vehicles

geologic

Because

in serial

launched

regarding

structure?

Asteroids

technology

they offer

data which

tremendous

(or parallel)

of elements

the asteroid

advancements

the asteroids

in a dormant

the possibility

data returned,

to play a major

multiple asteroid

here will produce

hopping missions,

of of science

visits on one mission.

in space transportation

is provided more quickly

The science extracted

aided by the payoff of high

If and structure

2.0 High Energy Mission Applications

propulsion. magnitude amount

of a large in the by flying

have of even greater

the origin from the planets

will enable of using

and development is expected

solar condition, origin of a once

and compounds role in understanding

enabling the type contemplated

formation. or are they masses

belt will be particularly High

Explorations performance planner Earth

the mission singular targeting low performance

knowledge Are the Asteroids which

the solar system or planetary existing

of propulsion. to perform asteroid

composition reveal clues about mechanisms and the chemical nuclei, primitive Exploration,

requiring many trips to a large number will be a much more efficient with sufficiently

planetary composition internal theory will be better constituents chemical

As stated in the recent National Research Council Space Science Board report,

program could Large, massive analysis and others.

instruments and to perform measurements

understood. could require a very energy

asteroids; of comet these most Lunar and

In this area we will want the asteroid

For a single launch from Earth orbit, additional

Multiple Asteroid the propulsion

of differentiated character

…intensive will overall

large power to accomplish

characteristics, of

sources. in-situ issues

planetesimals p. 24)

are expected nebula;

under what (Don88

of planetary theories

of Asteroids. provided

To gain a valid statistical

high energy are available.

and the origin of planets.

will be used to compare

the of into a

to know the following:

conditions Planetary

If the latter, accretion

study and exploration

belt and its radial

the above science

be made possible

hopping systems

by the availability

the wide diversity

the protoplanetary

can be taken

determinations

that powered

and physical

with existing

the evolution

the structure

that address

to determine

and rapidly

of missions,

of asteroids

constituents

composition

the former

penetrating

is proven,

exploration

analytically

to targets

conducted

variations

approach

remnants

planetary

sampling

intensive

structure

accreted

scientific

in order

covering

A more

samples

the of

to the

formed.

remain.

series

which

never

2-61

that

the

can

belt

etc.

i.e.,

and

The

high

than

using

Earth

NASA

history

quickly

parked

matter.

system

comets

probes.

Comets

contrast

in solar

Perhaps

assume,

achieves

launched

are less

variations

primordial

and, we

associated

in science

information

productivity

the life of

composition

environment

in chemical

improvement

could more

have A

with multiple

a tremendous

on the origin

By performing

An observatory

the differences

map Asteroids.

in a retrograde

in the Asteroid

such missions,

to to the

larger sample

energy. orbit,

and the comets

the solar winds,

number mass,

can be anticipated

comprise solar

payload costs

They asteroids.

returned losses

a larger time

change the solar

significant nature

radiation, over

considered exposure

solar the theory

assembling future.

The experienced

of asteroid can

plasma experienced

contain Earth’s Maybe,

visits accomplished

system will be a key piece

the asteroids exposure,

between environmental

encompassing without

Do they through water?

spacecraft, and accurately

2.0 High Energy Mission Applications

of life, originate? knowledgeable

basic atmosphere. as man

from less than and the power

energy missions three than less

targets ranging to be massless

from 3 to 6 bodies

performance The Asteroids

they supply asteroids

for sample computational

be performed depending

targets The mission

more aware environment.

varying the specific

analyzed performance

of multiple used were

life may be written within

Multiple destinations.

for multiple considered

that a 20 MT payload

one year number

target was one AU.

Did they about

include Oort Cloud

to the first Asteroid

calculate Asteroid

which between

passed Earth’s

The calculations

return missions

was expended

How did they

2.34 to 2.37.

to rendezvous

The assumed

the extinction

at a distance

could years

and become

in projecting

the function

the comets.

the number

The curves

learn more

oerformance

the moons

the sample

of 1.5 AU.

of asteroids

in acquiring

are shown

to perform

data were

calculations

transported

The study

of specific

of species

10 kW/kg

techniques

of meteor

Fig. 2.34

3 and 6.

separation

of comets

propulsion

and their

is, 0.067

on Earth

deposited

missions.

missions,

planetary

providing

becomes

selected.

scientific

between

variation

and its

in Figs.

in times

science.

Asteroid

analysis

asteroid

function

comets,

powers,

assume

we will

building

designs

on the

Mission

mission

ranging

specific

10 MT

outpost

planets

sample

system

vehicle

visited,

targets

activity

kW/kg,

effects

should

and/or

Based

shows

where

power

as a

return

about

visits.

effect

same

mass

block

show

other

outer

initial

upon

data.

each

used

were

to of

2-62

high

only

with

was

The

and

that

and

that

the

1.0

the

for

its

;

,.,

i /I

_ \

’, _:

…

; ,., ’,

…

0.067/3

0.067/4

0.067/6

1/4

’, ”,’,.,-_

6 visited

=lOkW/kg

Applications

… …

I _ , _ _ i

o_n= 1 kW/kc

_ _. : ’ : , t ;

(z = 0.067 kW/kg

-, \

\,,_

\

2.0 High Energy Mission

/‘/ii

//ii

lO,4

10/6

Specific power/# of asteroids visited

’_ ’, ”,

’,,,”\
”,.-X\

’, _ , * , , _. :
-’.,. ,,,,

…oo,,,,

system first, 10 kW/kg, of 50 MT, Fig. 2.35, 3 asteroids

the most optimistic for a modest propellant

To consider note that be visited

one will can in only

using a 10 MT in-bound

specific investment

and the samples

with flight duration

return mission,

vehicle mass

0.9 year.

returned,

payload,

Flight Time,

6 asteroids

Fig. 2.34

3 through

variations

power

Asteroid

sample

2-63

visited.

years

initial

for

! I

¢/’)

I-

,,.

10/6

…

3 visited

6 visited

…

”…’.,

(Xp = 1 kW/kg

… …

C¢ = 10 kW/kg

0.067,61/51/41/3

10/3 10/4 1/6 10/5

0.067/3 0.067/4

x
”__’_., % ’%..,

(z = 0,067 kW/kg

Specific power/# of asteroids visited

…o

2.0 High Energy Mission Applications

In the case of a system designed drastic in propellant consumption years, an investment

there is a from 50 MT to a 820 MT from 1.9 to 1.4

to reduce the trip time only by one half year not

Asteroid sample return mission, propellant mass variations with flight duration for 3

The same 50 MT of propellants a visit

likely to be made during the course of a 3 visit mission.

to meet a specific consumption

the 3 and 6 visits are respectively

The averaged seconds

Alternatively, returned

less that 4 years allows

using the same quantity

6 visits with samples

for Fig. 2.36.

and 30,070 seconds,

can be accomplished

power of 1 kW/kg,

time is extended

Isp requirements

to 6 asteroids.

of propellants.

to 1.7 years,

through 6 visits.

over slightly

the flight

expended

increase

Fig. 2.35.

in order

20,900

Flight Time,

2-64

years

1’00

(/3

(1)

Q. O3

1/4

1/3

._o

10/4

10/5

10/3

10/6

10 4

10 6

…

visited

1/5 1/6

0.067/5

0.067/6

0.067/4

0.067/3

Applications

O_p= 10 k_l__

O_p= 1 kW/kg

= 0.067 kW/kg

… …

2.0 High Energy Mission

Specific power/# of asteroids

higher at The average specific impulse for the (Zpl 0 missions is substantially slightly over 50,000 seconds for 3 visits and nearly 60,000 seconds for the 6 visit mission. of fusion’s performance potential.

The o_..1 system’s Av requirement year tr_‘ptime, and 225 km/s for the 6 site visit.

(Fig. 2.37) for the 3 site visit is 167 km/s, a 1.9

feasible based upon current understandings

… Flight Time, years

These all appear

with flight duration

return mission,

Fig. 2.36.

variations

…

2-65

Asteroid

6 visits.

impulse

through

specific

sample

for 3

_”

1/6

1/5

1/4

1/3

’”

10/6

10/5

10/4

10/3

…

300

kW/kg.

visited

0.067/6

0.067/5

0.067/4

0.067/3

,4 >-

6 visits

= 0.067

3 visits

6 visits

200”

500”

5 _\visits

4 visits

(z p = ,

kg, 6visits

= 10 kW/kg,

Applications

Specificpower/# of asteroids

2.0 High Energy Mission

visit and remain within then a reactor size of 3 to 4 megawatts of higher

accomplish limit of technology the 10-year mission.

A Or,p0.067 vehicle, approximately seconds propellant.

the same mission impulse. of

performance That mission If the power

10,000 nearly 25 MT of lower

time from 7.7 to 4.6 years. for a 6 visit mission,

That mission consumes of propellant

the flight capability consumes reactor’s

of magnitude Now if we wish to

the (Zp0.067 vehicle results.

to accomplish to one megawatt

a minimum of under

requires and to remain

for specific increase

life. reactor the reactor

of averaged A gross

the 7-year to provide

specific is required.

for a 7-year, 3-site visit

life can be extended,

112 MT of propellant

gap is the production

necessary increase

this 3-site mission,

time of 10 years

these missions,

impulse Another

by 705 MT will

levels, 200 N,

the 6-asteroid

to accomplish

but exceeds

ion engines,

the quantity

is needed.

the upper

7.7 years

return mission,

an order

for 3 through

To meet

in order

a flight

with flight

Fig. 2.37.

variations

thrust

Asteroid

duration

then,

6 visits

velocity

least

sample

2-66

Time,

Flight

years

have

been

2.2.5

INNER

defined

examples

PLANETS

set of mission

the anticipated

Mission These,

2.0 High Energy Mission Applications

Discussed missions examine

of science within the solar system.

and science beyond the solar system -

previously for the conduct a lesser

mission flight performance parameters were not computed.

The low thrust approach was Hence,

performance too, are targets which could benefit by a high energy

calculations were not performed for Venus and Mercury. transportation

system which performs sample return missions. not considered to be as accurate where the effect of gravity is greater.

the next step in space science given much them is the stellar missions. science

missions missions. attention not available. space science Included

where the targets within the solar system.

interstellar medium and the other concerning

Two subcategories of

flight future In this section we

since the energy means for propulsion

termed as being beyond the solar

INTERSTELLAR SPACESCIENCE

the science instrumentation

The chart below presents

SPACE OORT CLOUD MEDIUM

STELLAR SCIENCE

ALPHACENIAURI BARNARD’SSTAR

in the latter category

the type of missions

THESOLARSYSTEM B. SCIENCEBEYOND

are astrophysical

These missions

are considered,

are capabilities

and conduct

to enhance

and power

one which

to conduct

categories,

not been

examines

comprise

involving

namely,

system.

related,

REGION

a set

those

have

2-67

that

lies

but

limit

-Cosmic

-Element

(potential)

astronomy

-Interstellar

-Heliosphere

*low energy

compositions

high energy

waves lens

and compound

-Dust particles

ray measurements

-Fields and particles

-Astrometry -Plasma

Interstellar Space Science

-Gravitational -Gravitational

2.0 HighEnergyMissionApplications

Interstellar Space Science Missions, the second category of Space

A list of Science Missions considered, is provided below:

sun’s age (~4.5 billion years) .old

also Oort Cloud and comet-type

Composition elements

(relative to Earth-based)

.young

sun size

-Presence formations

of star characteristics

limits of other stars

Stellar Science
Plasma/chemical

system planets,

solar astronomy

-In-situ analysis

-Search for life

of star systems

in star systems

[probe/lander]:

temperatures,

-Comparative

Size, mass

-Oort Cloud

of extrasolar

-Heliosphere

.Distribution

compounds

properties:

-Dynamics

-Planetary

reflectivity

organics),

Physical

formation

analysis

-smaller

(water,

.larger

2-68

2.2.6

OORT

CLOUD

in the region

Mission Descri.otion

2.0 HighEnergyMissionApplications

cloud resides it can not be explored

.Solar system based telescopes (remote from Earth) -Solar observatories -Polar solar characteristics

-Imaging -Formation of star versus planet -Presence of water and organics beyond the solar system -Fields: gravitational and magnetic -Electromagnetic radiation spectrum -Solar System Based Instrumentation

The Oort within the mass present. infrared direct exploration by a rendezvous, magnitude Science determine their acquired Oort Cloud likely cloud’s yield system, primordial changes models. will also be achieved

Kelvin making for The science to be gained the large Based to and if present,

will be The imaging data from the the data will not ever the Oort of and asteroids may the solar

their composition, data for the Oort planetesimals and moons.

spacecraft This would serve as a multiple purpose mission.

could of organic molecules, property for the planets

observations of in-situ

if the science data are to be obtained within a reasonable

and of solar system system

is not achievable by fusion.

of 20,000 telescopes is only

time. Very Cloud mission

very meaningful particularly

and dynamics is considered

Laboratory the presence

on the origin cloud mass

should result Unique

concentration. similar

be obtained physical

No other means of energy

of to comprise

The mass of

of solar system dynamics

from the above to benefit

due to the low reflectivity

interest telescopes.

suggestion targeted.

solar system matter.

Mission .oerformance

analysis, provided

from Earth difficult.

those bodies other

from Earth based

the long distances

essential little

the Oort Cloud.

As the result of

AU and beyond.

the region with

Better knowledge

A Large Space

The temperature

from instruments

is to fly stellar

to be traversed,

characterizations

a large energy

the construction

will hold great

in this mission.

and chemical

autonomously

planetesimals

Comparisons

with comets

than fusion.

experiments

information

astronomy

by optical

is known

of power

the solar

the Oort

regarding

increase

(LSBSL)

Physical

degrees

analysis

conduct

Another

through

located

outside

several

without

to that

source

station

exists

since

other

stars

2-69

Oort

Vv.vu/

rather

results

vehicle

system

actually

for the

inherent

duration

systems

of more

purposes

of mission

considered

and flown,

achievable.

performance

the multiple

are currently

for propulsion

stage vehicles

from including

for comparative

to initial mass

here. gained.

values was calculated

stage further enhances

due to the high payload

applicable the distances

That additional thrusting

The advantage This

to 20,000 AU. The (z..,, ,,_-, vehicle

than one stage an added

for the fly-by and rendezvous missions

2.0 HighEnergyMissionApplications

shown is negative; penalize

to missions beyond and mission duration

the solar system because far exceeding

The value of 100 such that on

than to imply A 10 MT payload was flown

the reactor’s The results from the mission are presented

design is the additional stage system reliability

of using 1 to 3 stages were evaluated. calculations

A series having specific powers of 1 kW/kg, 10 kW/kg, and 100 kW/kg. kW/kg was added values both fly-by and rendezvous missions was not considered the enormity life. Vehicles performance in Figs. 2.40 to 2.47.

The mass impact of staging the vehicle for the trajectories the design selected overall performance considered reliability redundancy. long engine reduced. approach propulsion non-trivial rendezvous.

These mission to minimize systems must endure a firing period lasting for 2/3 of the flight categories matter.

A more reasonable mission on a 2-stage O_plOvehicle with a gross weight of approximately one or two-stage The flight

A mass mass is required just the initial vehicle mass is increased mission.

years, and hence no mass-time a good approach That intersection addition of another

to enhance mission is referred in this text as the “stage stage adds 4 more years to the flight

(Fig. in length those flight times If a system could to about the high speed trips.

The fly-by mission 2.40) depending being for specific be designed 13 years.

upon the performance powers of 10 kW/kg to 1 kW/kg respectively.

is incurred by adding the second reliability with no performance

with optimal calculations and propulsion

stage, penalty. The to Fig. 2.38.

low thrust missions the optimal

from 1,000 MT to 80,000 MT for a 30-year

for pure since the is

used system mass;

from a mass perspective

two orders of magnitude

the time would decrease

is to fly a 40 to 45-year

vehicle mass penalty

There is a substantial

flight therefore,

to reduce 8 years of

time is approximately

power of 100 kW/kg,

200 MT. at 43

the reactor design,

time, a and

time in a 38-year

invariant” mass.

35 to 70 years

time for either,

are considered

the propellant

Two mission

for a 3-stage

e_plO vehicle

time. Refer

to a specific

performance

MISSIONS

is nearly

of nearly

vehicles,

increase

identical

FLY-BY

solution

penalty

flight.

fly-by

flight

That

2-70

for

is,

’,

I-

"""

10 2

,_ “E m

” ” …

""" …

"""—…

Applications

_p = 10 kW/kg

c_p = 1O0 kW/kg

2.0 High Energy Mission

o_pl0 vehicle shown in Fig. 2.39.

140 MT to 150 MT for the

that 40 to 45-year

vehicle mass variations

is approximately

The propellant

Flight Time, years

with flight duration

The quantity

of propellant

consumed

fly-by mission,

configurations.

and 3 stage

Oort Cloud

masses

period.

Fig. 2.38.

1 stage _

during

for 1, 2,

2 stages

…

2-71

initial

are

120

160

200

2”0

I-

”_

cE OO

”’”-

"""-

""""

10 2

10 4

10 3

’;’:;_“ql-----

3 st ag e s

kW/kg

1 stage

(Zp = lO kW/kg

(xp = 1O0 kW/kg

2.0 High Energy Mission Applications

Oort Cloud fly-by mission, propellant mass variations with flight duration for 1, 2,

The average seconds.

and 3 stage Configurations.

Flight Time, years

and 220,000

is between

(Fig. 2.40)

210,000

Fig. 2.39.

impulse

specific

2-72

100

,_ ,B

Q.. co

100

10 6

10 4

_‘10 5

2 stages

Fig. 2.40.

Applications

Oort Cloud

_p = 1 kW/kg

(Zp= 10 kW/kg

(z p = 100 kW/kg

2.0 High Energy Mission

is considered 3,000 km/s.

range That approximately

a, b, and c)

achievable.

mass variations

fly-by mission,

configurations.

The Av

for 1, 2, 3-

Flight Time,

with flight

propellant

duration

2-73

(Fig.

vehicle

2.41

stage

years

160

200

4000

8000’

>- e_ .,,_,

o kW/kg

Applications

(z = 10 kW/kg

’!_!ii!ii!=i

2.0 High Energy Mission

!!i!!=!!ii!!ii!i!iii_iii_ii_

<w o

Oort cloud fly-by mission,

Flight Time, years

for a single-stage

for a 2-stage

Flight Time,

Fig. 2.41 b.

Fig. 2.41a.

variations

10,000”

vehicle.

velocity

2-74

2000”

4000”

6000”

years

1000

10 kWfkg

100

:>-

kW/kg

/00

6000

4000

kW/kg

2OOO

12,000’

10,000.

e[p = 1 kW/kg

_ p= 10 kW/kg

Flight Time, years

2.0 High Energy Mission Applications

Fig. 2.41c. Oort cloud fly-by mission, velocity variations for a 3-stage vehicle.

50 year for a O_plo system, and 100 MW for the second. to accomplish compared fast mission. will only commence is to conduct below.

requirement stage is 347 MW are times and for a AU mission as mentioned, Stellar missions are discussed

The o_,,, system suffers a severe time problem because vehicle mass of 200 MT takes 95 years of

flight duration The single stage jet power key mission

requirement figures flight a 20,000

in Table 2-2 a. and b. for both the stage invariant

jet power output is 400 MW for

a joint Oort Cloud - Stellar mission.

the Oort Cloud, Another

2-stage with the 40-

The reactor mission

size of the region.

for the O_pl0 vehicle.

a 43-year mission.

time in comparison

a comparable

to penetrate

approach,

of merit

45.8-year

the vast

interval

the first

Because

flight

2-75

The

120

IJ/

110

111

106

160

_pl0

o_pl

52.9

O_pl

°Cpl0

2,904

1,344

1,441

kW/kg

99,690

O_pl00

Mo, MT

Pj, MW

t, years

228,985

245,940

106,000

Iststage:

Mp, MT

Ist stage:

AV, km/s

I st stage:

3rd stage:

2nd stage:

OCp, Stage

stage invariant

<lsp>, seconds

initial mass, 10 MT payload.

2.0 High Energy Mission Applications

for the Oort Cloud fly-by mission using fusion energy, 2

TABLE 2-2a. Figures of merit and 3 stage vehicles, approximate

2-2b. TABLE energy, 3-stage vehicle, mass, 65,375 MT propellant mass.

the Oort Cloud fly-by mission using fusion time, 10 MT payload, 80,000 MT initial vehicle

The Oort Cloud mission through paradox.

presents the Oort Cloud

Yet at 20,000 AU the spacecraft

opportunity interest.

science measurements

is only beginning

Pj, MW, Stage 1

Pj, MW Stage 2

Pj, MW Stage 3

<lsp>, seconds

with somewhat

RENDEZVOUS

Figures of merit

Ist stage: 4,000

Ist stage: 3,632

2nd stage:1,453

the mission

to penetrate

O_p, kW/kg

km/s does

on science

of a the

to conduct

not afford

of that

2nd stage:l

MISSION

extended

at 3000

3rd stage:

1,389,000

AV, km/s

planner

targets

492,000

462,700

138,900

108,130

232,960

t, years

O_pl00

13,890

50,190

69,430

10,267

Flight

2,690

6,689

6,236

2,212

6,943

4,766

3,470

2-76

flight

,000

21.3

13.9

100

581

347

109

fast

for

_pl

That

exist.

taken

vehicle,

time will

presented

is a point

calculations

in this study

and certainly

are collectively

the region for

time calculated

The results of

into consideration

a strong desire to explore

2.0 High Energy Mission Applications

to 47 years for a o_pl0 vehicle,

to 22 years for a O_pl00 vehicle.

varied from 102 years for a 3-stage

the rendezvous mission performance

the first in the discussion

region, undoubtedly below.

in Figs. 2.42 to 2.45. The minimum flight

Initial vehicle masses are shown in Fig. 2.42.

The change of 1 kW/kg, 10 kW/kg, and 100 kW/kg is illustrated, vehicle achievable, vehicle than 1 kW/kg, a more massive

while from the fly-by and rendezvous mission from a single

powers size of the are the initial no higher time as

loading the system can be designed

there will be a science is,

vehicle will be flown to shorten the flight

stage with another mother

If only the lower payoff

initial vehicle mass variations with flight duration

Fig. 2.42. Oort Cloud rendezvous mission,

one payload continues

for 1, 2, and 3-stage configurations.

invariant mass approach

rendezvous mission

the stage but

to a 10 kW/kg system.

Use of discussed,

this time a difference

stage spaceship

specific to more

braking maneuvers

conducts with

up to 105 MT.

as is the massive

to effect a joint

an Oort Cloud

in performance

Flight Time, years

using specific

as previously

is suggested.

for example

advantages

penetrating

in mission

propulsion

compared

structure

between

systems

designs

. .

design.

reactor

heavily

:_ 103

power

1 stage

offers

stages

That

2-77

One

"" _

,,-,,,,

stag

412

es\

for

’,_

can

that

from

point,

5 MT

power

thereof.

between

electrical

sufficient

and still

examined

spacecraft

adequately

accomplish

be further

from LEO.

to optimize

a technique

That divides

for propellant

as the design

then the flight

The spacecraft’s

whether science

into two separate

to the Oort Cloud.

the 10 MT payload

mission that extracts

the maximum science.

A rendezvous mission’s

size would provide

55 to 120 years, depending

2.0 High Energy Mission Applications

launch payloads simplified

i.e., 10 kW/kg versus 1 kW/kg.

performance Av splits for

or some mass solution

is a conceptual, benefit

More sophisticated to determine

the 5 MT payload objectives

Further analysis would refine the split, but

This 50-50 split the maximum science

time can be expected ingenuity upon man’s

combination to the goal of securing

initial vehicle mass will be on the order of 3,000 MT.

in greater depth will calculations and rendezvous

The computations kW/kg are shown in Fig. 2.43.

one visit out by/rendezvous explore desired

it points fly- a joint This study did not the

is a subject discussed mission the appropriate

power. in the next section. have to be performed for fly-by.

that value is chosen be somewhere build a high specific power unit,

rendezvous mission, propellant mass variations with mission duration for 1 to

the o_,,,_.,uand the O_p,,- would use 2,100 MT of

Both spacecraft propellant.

impulse

Flight Time, years

at 10 kW/kg

are presented

op= 100 kW/kg

Fig. 2.43. Oort

in Fig. 2.44.

consumption

The specific

o_p= 10 kW/kg

for vehicles

200 220 240

140 160 180

1 sta””'ge

10 0

variations

vehicles

3 stages.

z stages

100 120

260 280

-.6-------3

and 1

60 80

stages

to to

”_-__

2-78

102!

10 5

_”-,

”_’”

”A”

4,,,

o Q.

10 4.

-…

10 3’

10 1

…

N,—

¢) C).

…—

’-! C). E

10 5

/f”

10 7

10 6

stages

1 stage

Applications

Cq::)= 1 kW/kg

ctp = 10 kW/kg

oq:)= 100 kW/kg

3 stages!

2.0 High Energy Mission

specific propulsion vehicle

in Fig. 2.45 a, b, and c.

to be 106 seconds.

system exceeds

Av’s are given

is considered

an times.

for flight

stage of

requirements

limit during

the longer

Flight Time,

Oort Cloud

rendezvous

with flight

Fig. 2.44.

systems

impulse

variations

system

duration.

mission,

impulse

fusion

specific

single

upper

_ploo

some

2-79

years

limit

The

that

the

100

250

for

100

200

_/oo

Oort

4000

2000,

cloud

1o0oo

kW/kg

Energy

Mission

2.0 High

Applications

Fig. 2.45a.

Ctp = 1 kW/kg

Flight Time, years

e-,=

,<__

Flight Time, years

for a single-stage

ap = 1 kW/kg

rendezvous

2-80

a 2-stage

variations

mission,

velocity

__kW/kg

vehicle.

8OOO

2.45b.

_W/kg

10000

6OO0

cloud

2O00

Oort

1O0

q) E3

Fig.

300

200

E ,v’

for

(.)

/kg

v, >-

6000

.,…, Q t-,

8O0O

14000

Applications

O_p= 1 kW/kg

(z p= 10 kW/kg

Fig. 2.45c. Oort

2.0 High Energy Mission

____/

high energy missions initial

of 6,000 km/s. To perform the

high reactor mass

The These 55-year

increment levels.

demand vehicle

and fast mission

is approximately

350 MW third

7 GW second

140 GW first

cloud rendezvous

(xpl 0 vehicle

requirements.

2-3 a. and

in summary

b. compare

a maximum

jet power.

MT which

for a 3-stage

Flight _me,

invariant

mission,

requires

variations

3-stage

velocity

power,

attains

mission,

format

stage,

power

vehicle.

velocity

3,000

Table

stage

2-81

years

and

the

105

111

117

(Zpl

55.5

O_pl

(_pl0

7,030

2,129

2,963

5,245

6,940

3,261

4,000

2,380

2,129

2,963

2,435

3,261

4,000

O_pl 0

o_pl00

85,280

82,860

178,520

Pj, M W

Av, km/s

Ist stage:

3rd stage:

2nd stage:

Stage s

O_p, kW/kg

<lsp>, seconds

initial mass, 10 MT payload.

t, years Mo, MT Mp, MT

2.0 High Energy Mission Applications

for the Oort Cloud rendezvous mission using fusion energy,

TABLE 2-3a. Figures of merit 2- and 3-stage vehicles, approximate stage invariant

for the Oort Cloud rendezvous mission fast

using time, 10 MT payload, 80,000 MT

TABLE 2-3b. Figures of merit fusion energy, 3-stage vehicle,

initial vehicle mass, 65,375 MT propellant mass.

Pj, MW, Stage 1

Pj, MW Stage 2

Pj, MW Stage 3

<lsp>, seconds

O_p, kW/kg

2nd stage:

3rd stage:

1,389,000

Ist stage:

Av, km/s

384,600

395,840

138,900

136,240

293,500

183,730

t, years

O_pl00

29,430

11,300

70,300

11,050

10,550

13,890

63,240

69,430

12,936

1,055

4,000

3,261

3,470

2,963

2,129

1,580

2,787

6,943

6,004

3,470

5,127

flight

2-82

102

347

of to

time.

2.2.7

stars.

is 1.7

NEAR

EARTH

requiring

is clearly

The next

STELLAR

MISSIONS

B. Stellar

accomplish,

Barnard’s star

4.3 light years

Alpha Centauri

The star nearest

at 4.3 light years.

Mission Description

a lengthy period of

to Earth is Alpha Centauri

TABLE 2-4. Stars nearest Earth

This class of science missions

2.0 High Energy Mission Applications

the distances the most difficult

light years further as shown by Table 2-4 below which presents the 6 closest

known star systems. multiple great systems. granularity processes systems? Understanding impact understanding in general of percent of “stars” are in reality star systems. Work accomplished shows

An on-site not otherwise that transition At what point does solar science

particles relationships missions will provide the solar system’s

and the in since a large by Harrington for billions

observation possible. from pure multiple

objectives. ray in-situ data from far out of

type stars are There is coupled offers

to comprise the first plasma and cosmic

A prime mission planetary conditions.

and What are the dynamics

converge and the interrelated

and stellar wind These

for a binary star system (Har77).

on the star system development

such multiple proportion

or star systems

in learning more about

Abt and Levy concluded

was found concerning

that orbits of planets

solar science?

zones will be stable

less than 100 years

that 54% of all solar

could be beneficial

which characterize

a very significant

and evolutionary

to the question

in some orbital

having periods

major mission

of one, exists

No information

provide mass

the interstellar

ecliptic plane.

with planetary

that dynamics

the dynamics

Measurements

the remnants

the formation

spectrographic

star systems,

star systems

Sirius System

star systems

Luyten 726-8

star of all

to planetary

of whether

of multiple

and which

of multiple

the solar

dynamics

gathering

approach

Wolf 359

expected

concerns

comprise

objective

systems,

answers

systems

physics,

Lalande

Multiple

interest

(Abt76)

fields,

under

years

data,

solar

2-83

data

and

star

are

6.0

7.7

8.2

8.7

9.0

…

for

may

stars,

stellar

without

Interest

suggest

analysis

to have

chemical

summary

planetary

in binary

occurred.

of binary

ideas of

by planets.

companions

of planetary

is illustrated

of extrasolar

star systems.

are extremely

the proposition

by Harrington’s

of 3 star systems.

have not yet provided

planets arguments,

2.0 High Energy Mission Applications

Observations the existence

the origin of our own planetary

life, young stars are eliminated

evidence The observed

any persuasive systems.

the comparable presence

the 40 percent be

in the question (Harrington:82:151):

If we are to look for time for evolution

coupled with current that most of

It is doubtful whether Such indirect

We still cannot dismiss (Har82) rare.

could also however, system is poorly that planetary

angular momenta how the solar system formed, stars or

accompanied exist are weak because understood. systems

necessary required in their planetary in the process billion years ago, elements candidates sun will burn out more quickly, well systems

elements in these stars and therefore by the older stars the sun some 4.5 heavier stars than the sun are A large sized is size. is less star on

That away. known odds these limited statistics, of planetary question important.

considered Eridani at 11 light years away. not considered

is Epsilon several more stars are is Tau Ceti at 12 light years

we may also not be able to consider although

stars within 12 light years distance stars

topic which may be addressed of planetary

elements were created At the time of the birth of

The first beyond Beyond Epsilon Eridani

What are the candidates? Barnard’s

The based on the very

are in the process of giving birth to planetary

for life as we know it, are believed deficient

older and younger parameter

fate of have to comprise

is a total of twenty for encountering

the matter may reside in the presence

to have formed, to examine.

and a small one will have a furnace

to the ultimate would

is the closest. stars are

there apparently was sufficient

Lets examine is the second

(multiple) to be debate

is the missing matter which

the universe 90% of

in the search for extrasolar

is the be visited

time for the necessary

of fusion fuel burning.

where disc formations

Young stars can, at

Of estimated

Another formation

lit. As mentioned,

the next candidate

Star, an old star,

The next several

them. closest.

due to planetary

on the basis of

least potentially,

of brown dwarf

Alpha Centauri

are eliminated

as candidates;

the mass of

by interstellar

the universe.

observatories

life potential

The heavier

this subject.

in multiple

is One

instabilities,

inadequate

and other

The other

so slightly

properties,

Old stars

too small

elements,

possibility

Barnard’s

formation

important

of Earth.

becomes

systems,

systems.

too old.

because

is 20%.

systems

nitrogen

oxygen,

system.

carbon,

interest

is that

having

seems

Thus,

stars,

there

2-84

Star

that

star

the

2.0 HighEnergyMissionApplications

if they do exist, can be better detected by an outpost astronomy

One subject of interest in the formation of solar systems is the presence of leads to the question of comets and whether some type of Oort water. That Is our solar system unique in that regard? That Cloud surrounds another star. is a significant question as we examine the question of life elsewhere and the importance of water for the existence of life.

those having considerably less mass than the sun, approximately 6% - an amount insufficient to ignite a fusion energy release. Perhaps brown dwarf stars, observatory, and, if found, the quantity of matter and statistical distribution must be such that they could well be within the range of a fusion powered spacecraft. they could be studied at close ranges by the use of remote sensing Thus, laboratories. Interstellar dust can be accumulated for analysis during the trip out to the stars as an additional benefit of the mission. The ultimate fate of suns which have burned out can be studied by in-situ spacecraft. Also of interest are any events which are rapidly changing, such as cloud motions, eruptions, explosive events, expansions, contractions, etc., which will benefit from the sensors of remote in-situ spacecraft.

As another mission objective, it could be very informative to compare our Earth- based perspective of the star with close-up in-situ measurements. Also, this mission provides a larger baseline for astrometry. Further refinements could be achieved by targeting a second spacecraft to a destination at approximately the opposite direction to some other star system on a separate mission. Some very accurate triangulation determinations would result as the relative distances increase. As another mission objective, additional data on the Oort Cloud region could also be gathered as mentioned in the previous section.

This mission category has received only limited interest by the science community. The mission capability does not exist. The NRC report addressed an “Interstellar Probe” mission using megawatt nuclear electric propulsion. However, at the suggested velocity of 100 AU per 10 years, the 270,577 AU trip time to Alpha Centauri will be in transit for 27,058 years carrying only a 500 to 1000 kg mass payload. For imaging, that is an inadequate mass for a mission of this magnitude.

The objectives of the mission are to determine the characteristics of the heliopause, low-energy cosmic rays excluded from the heliosphere, and global interplanetary gas and mass distribution of the solar system, and possibly, a much more precise determination of the stellar and galactic distance scale through parallax measurements of the distance to nearby stars. (Don88, Solar and Space Physics, pp. 41-42)

was given in this study to the definition

interstellar medium,

of an appropriate

size. A large,

The resolution

Consideration

light weight

is essential.

telescope

payload

should

stellar

2-85

over

plan,

then,

future

basis.

orbital

design

vehicle,

territory.

into the

powered

technical

telescope

into orbit.

Otherwise,

by-passing

assembled

be possible

performance

expectations

a pioneering

improvements

by fabrication

As discussed,

A light weight

in the on

aid by permitting

to Alpha Centauri,

to be a design target.

there are fundamental

Since the loads imparted

2.0 High Energy Mission Applications

less than that which would

to be met by the conduct of

for a mission rather

it would only serve as an abstraction

is to collect data, store it, and transmit

in a mission where the results are so far

This implies a size of no less than 3 meters.

are low in a fusion Freedom facility would

assembly by a minimal mass on Earth and

Why should there be interest future?

is to provide objective to a continuum of space scientists,

being passed along for some future generation, The proposed

such that data are than to only produce data at from an earlier those in it to

provide field. the order of 4 MT is considered by vehicle dynamics the Space Station structure, transported

One mission available its conclusion. generation between. Earth on an annual or biannual science objectives out unchartered not be lost trip out. be designed, provided reasonable

The considerations The other significant by or a rendezvous mission to continue this is such a rare opportunity. much additional as it proceeds gathered planets -their

If a means way at one or two “astronomical providing flow would be possible, the mission. density observations system conducted

science during the trip the space medium in that all science would on the occurred can to Earth, within

along the a continuum of data on the solar system, where the

interstellar defines goal loss of mission,

then a continuum of science the energy

for the earlier astronomers of

the trip system can be of

one would on the outbound on the star

new information beyond Alpha Centauri,

e.g., the presence etc. The rendezvous

term astronomy is less, may benefit

In a fly-by mission, to be obtained

but data at Alpha Centauri,

mission’s Figs. 2-50 through

by the spacecraft composition,

The preference of science

life system design

data from the star system since

not anticipate leg of

this mission should be a fly-

There is also the pragmatic

of permitting in solar

residing atmospheres,

from the unique advantage

Near of hydrogen

non-imaging a research

data could be transmitted

elevate system demands,

could be made available

to “leave” an instrument

joint propulsion-electrical

if a major malfunction,

system requirements

variable to consider

can be maintained

from the aspect

by any spectral

mass, seasons,

of high energy

the transmittal

is to conduct

as shown by

If an efficient,

a rendezvous

requirements.

from outside

one causing

requirements

consumption

experienced

high power

absorptions

establishes

unimpeded

operational

astronomy.

trip which

is whether

outposts,”

important

however,

package

mission.

reactor

restart

power

limits.

2-53.

cycle

flight

2-86

plan

and

that

tool

tests

gains

for a

unique

waves.

galactic

a black

(Don88)

physics.

traveling

to permit

discusses

spacecraft

are possibly

understanding

of our galaxy.

of gravitational

some science

of gravitational

in this region?

lens experiments

and Astrophysics

hole is surmised.

This mission would

using the sun as the lens.

to observe Is there

equipped in the solar

waves on different

range transponders

offers now inhibited

2.0 High Energy Mission Applications

compounds? to the center

such waves by orders of magnitude.

Are there organic penetrate

the Milky Way galaxy to a better contribute

opportunities by the galactic mass.

Earth based telescopes of

with dual system. The the might be

tests are too weak to detect velocities,

and distances may be of a sufficient magnitude Also, gravitational

to be made in gravitational report using spacecraft trajectories

An out-of-plane intergalactic matter and radiation, water have been unable to optically where

There The NRC Astronomy restricted frequency Current masses, resolution possible

This mission cycle, of 100 bits per second was considered imaging. MW of directed microwave Another quick requirement None of that size are known to exist. The transmitter mass is expected

by the competing appear may have formed and remained same mass and age as the sun and emits similar the sun and emits very little light, particularly appears the sun. presence that star systems

Are the to the planets will have been seized

a reactor duty A data rate the minimum for

in this star system is comparable in this mission will be to establish

the than which in age to the occur such

necessary Thus, of planetary masses

candidate multiple have been bred? Or

stability of a prolific area and conditions

At Alpha Centauri separation Alpha Centauri

is a three star system, is Earth’s

fields? great distance stable.

for life. The other one main objective

e_is approximately is smaller

indicates at indicated

Alpha Centauri nearest.

that the transmitter

the envelope power

power is substantial.

calculation is necessary

form versus solar planetary

is also the a good

a fortuitous sun size

stars structures

1 MW. The mass of

Mission performance

distance. level

to be at a sufficiently

for multiple masses

data was examined.

How does accretion

the Alpha Centauri

that approximately

in a star system.

as representative

is extraordinarily

in the ultraviolet

light. One star

is approximately

stars indicative

is the situation

and age and

and formation

that planetary

the individual

the planetary

the electrical

To establish

or do they?

independent

gravitational

A back of

demanding.

frequencies

to transmit

calculation

such that

to be 4.0

the stars

question.

Centauri

systems,

since it

One of

situation

required

analysis

energy

except

Alpha

hence

power

2-87

the

for

space

power

physics

applies.

possible

changes

Designed

capability,

intolerably

Propulsion

to transmit

calculations

into space.

for 2-week

the mission

for electrical

from outside

or biannually

is approached.

to to that

from distances

data including

is very limited,

system specific

the solar system.

as Alpha Centauri

it would be considered

and payload structure.

If the energy allocated

further and further out

to the sun the opposite

in the same parameters

as the new transmissions

to examine received

a continuum astronomy

science and update

offers new and comparative

to be held within 4 MT. That

data annually interstellar

2.0 High Energy Mission Applications

appropriate provide conduct

astronomy, data, we possess

data as reference that data

showed so. Much depends

that the are Thus, we

durations the opportunity to provide

a proximity to provide It should be noted that with regard

MT to 4.5 MT. The telescope mass is expected leaves 2 MT for other science instruments

operational is, using departure capability periodically can observe calibration

Mission performance they are not reactor. kW/kg were considered classes: magnitude Because

that while the mission times are long, power of the fusion upon the specific and 100 10 kW/kg, two mission for due to the losses.

mission considered, mass as assumed used in the mission stages were each examined. was required.

a 10 MT payload mass was the same and the transmitter, technique was 1, 2, 3, and 4

If a planet concentrate detection sufficient maneuvering

follow, the bulk of which is for the telescope

system’s There will be a significant

losses were not considered in small

the distances these are low acceleration

properties, the desirable the completion

rapid departure. due to the vehicle’s

A mass optimized flying

consumed that of

calculations. A high specific

and oxygen be to maintain

in the escape for a more

on defining instrumentation.

for the Oort Cloud mission.

powers performance

goal would of

energy above amount

of 105 to 10 6 seconds

fly-by and rendezvous.

to have the capability

there is an additional

the planet up close.

required inertia

Hence, at

from the solar

the interstellar

to overcome

be important

be detected,

of 1 kW/kg,

performance

its physical

gravitational

calculations

in mission

capability

missions,

immense

involved,

including

resulting

Vehicles

it would

quantity

impulse

journey

Gravity

should

water

size.

2-88

field

visit

that

For

the

for

460

9,015

4,184

4,205

range

Pj, MW

These

t, years

Mo, MT

showing

mission

Av, km/s

FLY-BY

program

MISSION

performance

for variations

practicality.

parameters

fly-by mission

Alpha Centauri

and requirements

in specific power

10 I

mission interest,

2.0 High Energy Mission Applications

,kW/kOI

to encompass interest

vehicle, 10 MT payload, 4,000 MT propellant

100 1100.0

TABLE 2-5a. capabilities for: single-stage mass.

from the study’s of greatest Fly-by Mission.

the mission for an Alpha a and

Results parameters Centauri wide determining

performance are presented calculations evaluating

calculations, in Table 2-5 a. to d. were selected stellar

TABLE 2-5b. capabilities for: 2-stage vehicle, mass.

in specific power 4,000 MT propellant

lO.O I

lOO.O

and requirements

10 MT payload,

<lsp>, seconds

Alpha Centauri

Pj, MW, Stage 1

fly-by mission

Pj, MW Stage 2

for variations

performance

OCp,kW/kg

Av, km/s

Mo, MT

153,110

329,870

710,675

141,180

304,167

655,307

t, years

56,000

10,011

21,569

12,100

81,620

19,500

39,200

19,422

4,646

2,600

8,162

4,873

3,500

4,205

1,950

1,800

8,440

2-89

T, N

F, N

370

195

1.0

694

365

F, N

3,500

6,940

5,270

54,900

69,400

13,900

80,000

24,460

11,360

t, years

255,000

139,000

555,102

120,000

258,000

Mo, MT

AV, km/s

1,390,000

1,180,000

performance

for variations

Pj, MW Stage 3

Pj, MW Stage 2

fly-by mission

Pj, MW, Stage 1

<lsp>, seconds

Alpha Centauri

10 MT payload,

10 !

fly-by mission performance

2.0 High Energy Mission Applications

pkW/kO I

and requirements vehicle,

100 1100.0

in specific power 65,400 MT propellant

TABLE 2-5c. capabilities for: 3-stage mass.

TABLE 2-5d. Alpha Centauri and requirements for variations 10 MT payload, 1,308,000 MT propellant mass.

Note the increase Nearly 30 TW are required for The complete 2.46 to 2.49. short

increases. systems. is shown in Figs. design points for one can observe

Fly-by Mission data provide single specific the initial mass variations,

data set The above tabulated From Fig. 2.46,

that a change 1 kW/kg to 10 kW/kg will

for specific the Alpha Centauri

capabilities for: 4-stage vehicle,

time by 193 years.

in the performance

of the propulsion

power systems

as the specific

in specific power

of 100 kW/kg

reduce flight

in jet power

<lsp>, seconds

Pj, MW, Stage 1

requirements

Pj, MW Stage 4

Pj, MW Stage 2

Pj, MW Stage 3

28,700,000

27,770,000

system’s

(Zp, kW/kg

1,330,000

1,600,000

6,170,000

2,770,000

1,390,000

AV, km/s

specific

Mo, MT

212,700

458,200

277,700

139,000

t, years

power

times.

12,500

13,900

26,900

98,700

69,400

flight

100.0

3,500

5,800

6,940

2-90

from

F, N

10.0

694

154

1.0

I-.-

X_.

400

10 2

10 5

10 6

10 7

10 1

/=1

…

stages

1 stage

2 stages

1 kW/kg

4 stages

0 kW/kg

Fig. 2.46.

*__ lo3

Applications

= 100 kW/kg

2.0 High Energy Mission

One will note that the multiple mass penalty systems efficiency. invariant with the number discussion. the reverse for the multiple stage designs.

The effect of changes mass of payload mass. For example, in Earth orbit of approximately flight years,

Due to the large of having an initial mass in only by 22

performance is in the Oort Cloud out initial vehicle masses, advantage would be shown

the vehicle’s to the extensive large payload mass fractions

The period propulsion increase of 26 years in flight

large payload mass fractions, where flight penalize

180 years In the case of o_.,,_ that , ply times snown;

consider 150,000 MT for a fly-by mission.

time for a payload mass increase from 340 to 362 years.

times are long, The stage propulsion by fusion’s

If the data had been computed situation will

90 years. high energy mission is quite

is attributed and the relatively The four

for .,^,. time beyond the quickest

Increasing The dominance evident.

to 100 kW/kg saves for this extremely

for the o_^1,, p u is an . ano Tor an

of stage invariance systems

time added is 14 years over the shortest

in payload mass were briefly examined.

further of specific power

mission inert mass of

time results with the addition

time vehicle earlier

of 1 MT to 15 MT increased

result, and a performance

at which as pointed

occurs at approximately

the fusion permitted

in flight a 3-stage

times. Use of

a small penalty

these vehicles,

and 85 years

O_plO0 system,

for still higher

an additional

performance.

The change

fly-by mission,

of stages

Alpha Centuri

the flight

intercept,

Flight Time,

initial mass

specific

for 1 to 4

vehicle

with flight

stages

curves

variations

power

duration

stages.

2-91

i.e.,

years

1200

for

i.t/vv

]

that

(Fig.

2.46)

mass

would

vehicle

appear

._ 10 4

_al0 2

masses

observe

and the

approach

are very

propellant

implement.

differences

astounding.

(Fig. 2.47)

10 6 -,‘J P/

stage trade

in the initial

o_ = 10 kW/kg

the four system

approach Using

invariance to

107 “_of. = 100 kW/kg

2.0 High Energy Mission Applications

to be a very worthwhile one will

MT to 10,000 MT, O_lO/4- 1,308,000

flyby mission, propellant mass variations with mission duration for 1

approximately approximately

Fig. 2.47. Alpha Centuri

decreased the

8,000 290,000

Flight Time, years

from 1,600,000

configuration,

to 4 stages.

The stage

decreased

propellant

seconds.

average

I_IT to

impulse

specific

vehicle

stage

mass

2.48)

initial

1200

10 -1

2-92

from

(Fig.

10 0

The

MT.

and

800

200

will

o Q

..I

10 5

10 4

10 6

10 7

”_ O.. O3

4 stages

2 stages

,’…

Applications

(Xp = 1 kW/kg

(_ P= 10 kW/kg

(z p= 1oo kW/kg

3 staae.s…

2.0 High Energy Mission

One significant fusion thrust 6x106 N at an averaged thrust will be large. Multiple

high is it It is not known that since the reactor solution.

The first stage power Av imparted

is the means to attain a sufficiently

levels this high can be produced,

10,000 km/s (Fig. 2.49).

(’-,50 kN) to accelerate

of 2x105 seconds.

24,000 MW for

offer a potential

is approximately

inconceivable,

the massive

this mission

for 1 to 4 stages.

(xpl 0. The

requirement

to address

technology

in parallel

Alpha Centuri

flyby mission,

operating

Flight Time,

engines

but not

impulse

vehicle.

specific

Fig. 2.48.

variations

impulse

specific

2-93

years

For

¢J

300

200

10 5

10 4

10 3

Applications

1SP-1 stage

IOSP- 1 stage

100SP-1 stage

o_p- 1 kW/kg limit

e[ p- 10 kW/kg limit

o_p- 100 kW/kg limit

2.0 High Energy Mission

10SP-2 stages 100SP-2 stages

(x p- 100 kW/kg limit

for a single-stage

Alpha Centuri

flyby mission,

ISP-2 stages

for a 2-stage

Flight Time,

Fig. 2.49a.

Fig. 2.49b.

variations

>- 10 4

vehicle.

velocity

2-94

years

1000

10 5

10 3

200

500

400

700

400

600

800

”

(,o

,…,

400

200

10 5

10 3

>-10 4

Applications

1SP-3 stages

10SP-3 stages

100SP-3 stages

a p= 1 kW/kg limit

O.p= 10 kW/kg limit

(z p= 1oo kW/kg limit

2.0 High Energy Mission

10SP-4 stages 100SP-4 stages

iiiiii!iii ii iiiiiiiii

for a 3- stage vehicle.

a p= 100 kW/kg limit

(z p= 10 kW/kg limit

(Zp= 1 kW/kg limit

Alpha Centuri

flyby mission,

Alpha Centuri

1SP-4 stages

for a 4-stage

Flight Time,

Fig. 2.49d.

Fig. 2.49c.

”

variations

”_ >-10

” l

” I

vehicle.

velocity

” I

years

2-95

years

10 5

10 3

600

800

r_ .1—’

”

’

will

fast

feat

level

data,

since

power

levels,

having

reactor

needed

mission

Applications

required

impulse.

selected.

A vehicle

propellant,

and perhaps

an extremely

be technically

for the massive

the stage flight

2.0 High Energy Mission

design technology

very high specific

the in order

of at our ability

as long as 180 years,

and with very high output

reduced to 3x105 seconds.

least 85 years to design

a new transmitter require and will

challenging for a flight depending

the vehicle will have to perform reliably

intensive mission since the source of nearly all of

power on the order of 24 GW

can be sent including the transmission

to burn for two thirds of the capability of stages

to stage would decreases is The thrust trip to 3x104 N and

system will be required design which provides by the number from that

The propulsion time. the life requirements substantially reduced impulse the specific

The Alpha Centauri engineering duration upon characteristics for the first stage.

This will be a fusion fuel thrust will be from burning the plasma without much added to produce the high specific

In summary, is transmissions science meet theoretical transmissions operational of nonpropulsive system duty being capable power during thrusting. up energy will somehow have to be stored as it is expected the reactor. for a self contained

level) data of to No flight the flight and also a reactor start- The reactor by to be generated will be set lasts 100

The Alpha Centauri show a highly energy specific, present 4-stage power of 100 kW/kg is provided

development. annually in transit. requirements obstacles data the duration electrical

in Figs. 2.50 to 2.53, Some to for 1, 2, 3, and the specific that as a value

(~10 MW output conserve To to Earth to provide That power

insurmountable plan to provide for cycle of diverting

and technically data points were

power power, a continuum

mission. from the curves

the calculations vehicles.

format, Table 2-6 a. to 2-6 d.

science mission and vehicle

As previously mentioned,

only as a figure of merit

mission data, presented

it should be noted that

level will serve as well

for a mission which

The annually

at Alpha Centauri

imaging, power

that we currently

New standards

RENDEZVOUS

as achievable.

for automation

trip duration

and artificial

in a tabular

rendezvous

challenging

intelligence

demanding

distances.

MISSION

proposed

extracted

consider

defines

known.

“quick”

years.

rather

twice

2-96

are

1.0

180

730

10.0

F, N

4205

5270

2-6b.

6,700

1,440

1,950

100.0

Alpha

31,100

19,500

24,470

11,360

Pj, MW

mission

t, years

825,600

383,200

177,880

Mo, MT

AV, km/s

O_p,kW/kg

(::Zp,kW/kg

capabilities

rendezvous

for variations

<lsp>, seconds

10 MT payload,

2.0 High Energy Mission Applications

Centauri and requirements

TABLE performance specific power )ropellant mass.

in for: 2-stage vehicle, 10 MT payload, 4,000 MT

rendezvous mission performance in specific power 4,000 MT propellant

TABLE 2-6a. Alpha Centauri capabilities and requirements for: 1-stage vehicle, mass.

TABLE 2-6c. Alpha Centauri and requirements capabilities for: 3-stage vehicle, mass.

rendezvous mission performance in specific power 65,400 MT propellant

10 MT payload,

<lsp>, seconds

Pj, MW, Stage 1

Pj, MW Stage 2

Pj, MW Stage 3

for variations

ap, kW/kg

1,390,000

Av, km/s

Mo, MT

192,900

415,600

895,400

139,000

202,000

939,000

150,700

202,000

699,400

t, years

12,614

27,175

81,600

44,500

14,310

30,820

80,000

13,900

69,400

43,600

100.0

5,855

4,873

8,160

2,060

9,580

100.0

6,640

6,940

3500

2-97

10.0

1 0.0

35O

305

370

270

694

F,N

1.0

F,N

244

350

10.0

2-6d.

7,310

100.0

3,500

6,940

<lsp>,

Alpha

13,900

33,930

15,750

69,400

TABLE

for: 4-

277,700

577,330

268,000

124,380

139,000

seconds

mission

t, years

Mo, MT

Centauri

2,777,000

1,600,000

1,308,000

4,900,000

1,060,000

1,390,000

&v, km/s

27,700,000

22,700,000

ap, kW/kg

rendezvous

Applications

capabilities

performance

for variations

stage vehicle,

Pj, MW Stage 4

Pj, MW Stage 2

Pj, MW Stage 3

Pj, MW, Stage 1

10 MT payload,

and requirements

in specific power

MT propellant mass.

2.0 High Energy Mission

The variation 2.5O.

initial vehicle mass as a function

The order of magnitude kW/kg decreases achieving only

power time by 300 years. is particularly the in-situ

improvement flight

to 10 of time the

initial vehicle mass variations with flight

time is shown in Fig.

specific not

The importance

power include

from 1 kW/kg

the vehicle’s

for 1 to 4 stages.

the conduct

the highest

_p = 100 kW/kg

for specific

noteworthy.

Or,p = 10 kW/kg

and does

The flight

Alpha Centuri

is shown

time for

Flight Time,

of flight

rendezvous

Fig. 2.50.

4 stages

mission,

duration

2-98

e_tage

years

10 7

10 6

10 5

10 2

10 1

10 4

10 3

F.-

¢5

c”

…

p v

10 6

10 7

10 5

flight

levels,

increases

P = 100 kW/kg

an increase

fusion fuel,

(z = 10 kW/kg

such as, at

is at approximately

from 8,000 MT to

To reduce the flight

than the fly-by mission.

design a (0_.1,, system)

least 20 years or more.

time for the stage invariant

2.0 High Energy Mission Applications

this nature should be lengthy,

lacking a man-made means to manufacture

the initial vehicle mass to ~1,590,000 MT,

science mission, which in the case of a mission of

new fuel source such as Jupiter will have to be acquired

such high power The propellant mass, mainly

demanding helium-3. 1,310,000 MT, Fig. 2.51.

time by i.e., The propellant mass for to the lunar supply of 3He, and clearly for a mission

The flight 290 years, 100 years longer requires 50 years to 1,600,000 MT from 10,000 MT for a 4-stage vehicle. the fast time is nearly equivalent some

requirements, Fig. 2.52, for the 290-year mission.

rendezvous mission, propellant mass variations with flight duration

Fig. 2.51. Alpha Centuri

impulse seconds

high, an average

Specific 380,000

for 1 to 4 stages.

become

__ 10 2

1 stage

quite

2-99

10 “1

10 0

10 1

f /

…

200

10 7

_. _

""_-

“q""-”

i106 ._o

’_ CO Q”

2 stages

3 stages

4 stages

..…_”*”

(XD= 1 kW/kg

?—‘—i_.""__-

c¢p = 1oo kW/kg

Performancelim,---

…

2.0 High Energy Mission Applications

the Av by 2,700 km/s; is interesting impulse be beyond velocity

The jet power a-d, years It 20,800 does the specific impulse additional

requirement. the 106 increases will not be optimized.

the first stage is 28,000 MW. 13,100 km/s; is approximately

rendezvous mission, specific impulse variations with flight duration

The Av, Fig. 2.53 it by 50

by an additional increases,

flight durations limit.

to note that as the specific

the specific any Thus,

for the 290-year mission

for a 113-year mission,

increases km/s.

For seconds

Fig. 2.52. Alpha Centuri

will vehicle

Flight Time, years

for 1 to 4 stages.

performance

requirement

to shorten

longer

power

2-100

1200

1000

2000

for

¢.}

200

600

10 3

10 5

Applications

*-_10 4 >

2.0 High Energy Mission

a p= 100 kW/kg limit

ap= 10 kW/kg limit

>-10 ¢0 .,,.., (3,) a

100SP-2 stages

10SP-2 stages

Alpha Centuri

1SP-2 stages

for 2 stages.

with mission

Flight Time,

for 1-stage.

Fig. 2.53b.

Fig. 2.53a.

rendezvous

variations

mission,

duration

velocity

2-101

vehicle

years

1400

1600

1000

1400

10 5

10 3

400

600

.,,-.

200

10 5

10 3

ii:ii:

”-” 04 >-1

Applications

1SP-3 stages

10 kW/kg limit

ii!iii:iiiiiii_!ii_i

2.0 High Energy Mission

. OooS ;

a p= 100 kW/kg limit

with flight duration

Flight Time, years

11_oS;‘4:tstga;:s

Alpha Centuri

1SP-4 stages

for 3 stages.

for 4 stages.

Flight Time,

Fig. 2.53d.

Fig. 2.53c.

rendezvous

10 kW/kg

with flight

variations

2-102

mission,

duration

—_10 4

lim= 1

velocity

vehicle

12O0

years

1000

10 5

10 3

600

400

600

’

that

and

For

drag

That

time

these

flight

years

earlier,

to fly

recalled

assume

without

is best

namely

Because

it should

vehicle.

instead,

the time

attractive.

physics.

function,

corrections

relativistic

to power

calculations

the energy

propulsion

discussion.

and power.

no interstellar

in establishing

for to the

a transmitter

breakthrough

to decrease

for 140 years.

at a data bit

stage invariant

system arrives

stellar missions

the same investment

additional that

power will be adequate

reduced by a technology

design is the one selected,

power. the o_,,,,, p, ivv

powered As discussed

in initial having be

2.0 High Energy Mission Applications

some major new breakthrough

is not expected in theoretical

than the minimum (100 bits per second),

a fly-by or rendezvous, An

a firing time of nearly 50 years, based upon a 4-stage

a rendezvous mission over these

time, of high specific 10,000 MT, is very

The mission’s in the development vehicle mass, flown

each reactor will have The rate so the

is likely to be a subject required be will for a fly-by. On the other hand,

If the 290-year to endure fourth stage more than 3 times greater reactor could serve a dual

The mission strategy, whether considerable accomplish length of significantly

During mission when distances. masses. artificial missions resident necessary mission hardware,

The search task. observing time as a result of the high velocity. regarding Board report,

to take place at Alpha Centauri Oort Cloud for Oort Cloud-like the vehicle’s of science

changing such studies may have begun by 1995, to explore the diversity in order

time for reformatting in-situ while the spacecraft

of of another to apply even more to their exploration.

is the AI design, along with the

for the study of small bodies, their

Extrapolated to the conduct rationale would be expected

spacecraft That would permit greater

for a trip to Alpha Centauri will pose a challenge.

equivalent the time for observations

and for mission at Alpha Centauri.

orbiting around Alpha Centauri will be a time

(AI) system to perform any desired

approach paced mission

consuming short philosophy

on the a more slowly

due The scientist’s

is stated in the Space Science

Although be continued

deceleration allows

for other space missions

of comets and asteroids.

Rendezvous comets,

(Don88, Planetar 7 and

Also, intelligence

a rendezvous mission

to Alpha Centauri,

Lunar Exploration,

the rendezvous

from the sun,

be inconclusive

As mentioned

are important

is of special

is traversing

they should

a rendezvous

requirements.

contingency

of comets,

rendezvous

of Earth’s

the same

be favored.

In a fly-by

asteroids.

data may

for planets

research

missions

behavior

system,”

planning

provides

distance

interest.

expense,

greater

p. 16),

earlier,

mission

to the

2-103

“solar

would

loads

with

The

and

the

and

Star

for a

longer

closely

vehicle

bodies.

Beyond

therefore

however,

operating

50 years

Barnard’s

is 6 GW.

to reveal

elements.

interstellar

Barnard’s

requirement

of planetary

The 4-stage

for Barnard’s

lack sufficient

life supporting

The results of

fusion powered

it was mentioned

It would certainly

be a good target

a 10 MT payload

to Alpha Centauri,

these observations

is a very old star,

Earlier candidate

for dynamical motions

lacking in the important

star has been observed

in 260 years, approximately

a fly-by mission was examined

2.0 High EnergyMissionApplications

star at 10 kW/kg than

presence granularity second considered

The initial vehicle mass is 2,500 MT. The first stage

the trip to Alpha Centauri. jet power

to have been conclusive. mission.

In addition at 6.0 light years. can deliver

for in- (Don88 Solar and field flying the solar for due high power consuming mission for which to of

Solar and heliospheric large plane changes situ physical measurements Space Physics, and plasma wind normal system never propulsion only the Ulysses explore conventional

that Tau Ceti, at 12 light years distance, would be a a 10 MT

payload, vehicle mass of 2,500 MT and a 10 kW/kg propulsion

capabilities of solar polar missions and in performing

the ecliptic would provide contemplated This is another

from close to the solar surface. the composition

Program has been designed Three mission

the first spacecraft the capability

or near satellite at 30 solar

for the solar probe with a 1-year period;

A rendezvous mission time increases

to the plane of before

an initial The first stage

physics in the conduct

is 6.4 GW, and the average

system from a spacecraft

In addition, of

of a poloidal magnetic

can fly by Tau Ceti

Mission Description

power ~483,000

is 16,500 km/sec.

circular radii;

a characterization

the solar poles.

heliosynchronous

in approximately

(a) an elliptical

high propulsive

to -650 years;

is the Av

for supporting

(b) a circular

to the large

requirements

composition

requirement

400 years,

transporting

A 4-stage

propulsion

the solar

assuming

demands

seconds.

systems.

p. 33,ff)

systems

SOLAR

system.

impulse

vehicle,

specific

beyond

require

energy

to fly,

output

2-104

2.2.8

orbit

are:

star

life.

the

for

the

fulfill

solar

2.2.9

trend

these

p. 54)

toward

energy

greater

leaving

velocity

Mission

science

SPACE

BASED

analysis

systems

Applications

missions

of space

REMOTE

sensitivities.

the growth

a 40 km/s

performance

the conduct

.performance

requirements,

TELESCOPES

and exploration

mission for

2.0 High Energy Mission

A long multi-mirror

large, and massive,

No mission mission

least heliosphere.

or other higher performance

While solar electric propulsion

particular requirements evident.

studies were made in this study to characterize

for a spacecraft (Don88 Solar and Space Physics,

Very power. transported located telescope on “Searches Fig. 2.54 depicts 10 km in diameter, angular field)

benefit telescope to a more optimally type paper As an example,

Signals” a giant space interferometeric and they are separated of such a system (where

sensor into Earth orbit and assembled

are The is in the near

away has been considered

observatories space for

telescope. by 10 astronomical

could based transport

from fusion be could

as discussed (Zuc82,

is ~10 -10 second of an arc.”

near-Earth and/or

the entire universe

for Electromagnetic

“The telescopes

electromagnetic

in Zuckerman’s

from Earth’s

interferences.

by Buyakis

resolution

position

2-105

units.

p11).

This

“7-

t AU

space

A giant

Fig. 2.54.

2.0 High Energy Mission Applications

well out The NRC Space

into space would Science

0.8 pc in Virgo. in fields

than of spectroscopic

are currently observations.

pc in M101 studies

observatories Earth

sensitive continuously

than populations

instruments. beyond

observatory the

to a point remote

would the whole

to escape ultra

be better area

from the from

the Earth will permit

that improved

and less of stellar

resolution Thus,

such man-made

Ultimately, Earth’s

much too crowded

far locations

for HST become

avoiding orbital

to accommodate

A few minutes

“A large space

An observatory

to be in

be necessary

at a distance

in low Earth

an enormous

is a mission

Observatories

can provide.

consideration

the conduct

astrophysical

as scientific

observations

the shadow

astronomical

Astrophysics

of massive

to a year’s

of 10 second

transporting

observatory

is uniquely

interferometer

Coherence

the Earth

usefulness

telescopes

Astronomy

astronomy

placement

ultraviolet.

to stellar

as fusion

a resolution

possible.”

telescope

ultraviolet

distances

programs

operating

operation

efficiency

is short,

exposure

on the

sufficient

of more

eclipses.

a large

radiation

scientific

provides

increase

as well

frequent

In fact,

vehicles

(Don88,

is very

sources

ground.

devices

provide

(BUY79).

quality.

limited.

equate

energy

in the

p. 52)

placed

based

power

debris

suited

Board

space

report

of arc.

2-106

could

Earth

having

large

such

High

data

orbit

take

time

also

The

and

that

and

into

the

0.3

will

for

and

power

2.2.10

Mission

LUNAR

electrical

presence,

are large

consumers

exploration

Description

processing,

materials

nor manned

maintenance

those missions

environmental

or are supportive

in the future include:

that can be anticipated

This is a mission category

having neither direct science

2.0 High Energy Mission Applications

but which are either supportive

Three lunar missions which

objectives other aspects of NASA’s goals.

at other The moon serves as a source of helium-3 which can be used The idea to by the

requiring large energy demands develop test and endangering

for of Local Planetary center. maintained for sustaining

It may be possible technique life without life here. for

will energy, of lunar “Utilization Arizona’s atmosphere, environment

“fields” as a safeguard plant single failure point

enabling planetary for Earth power extract

and power. surface was originated

for an airless, agricultural new,

as well as for space of from mining

of a suitable a suitable function

The moon provides the development

of the use The B. of

is the focus note, development

to provide is another mission

and the utilization laboratory

to make it feasible and Robotics.

a natural and qualification

As one example, in Appendix

the development resources.

The moon serves as a convenient

of planets may well depend upon

the proper life on another

local ores, a large consumer

of Wisconsin. Center

Resources” a corollary

temperature planet,

and That work

are under study at the

needed for construction.

the Earth’s atmosphere

require the acquisition

for the accomplishment

technology bodies.

for Space Automation

to build the materials

University Wisconsin

and for performing

in other sections,

electromagnetic

to settle planets.

of the technology

for the conduct

and conversion

local planetary

living quarters

the University

the settlement

for habitation

As discussed

the helium-3

Along at

transportation

encapsulated

is discussed

applications.

cold moon.

terraforming

Approaches

of research

considering

a critical

of energy

a manned

genetically

equipment

the lunar

propulsion

transmittal

laboratory

concepts

functions

research

isolated,

perhaps

altered

qualify

power

fusion

space

2-107

even

work

to to

and

the

for

Mission

analysis

levels

applications

0erformance

Calculations

the magnitude of power

2.0 HighEnergyMissionApplications

If one catastrophic event were averted by such a lunar laboratory, the expense would be worthwhile.

The moon provides a wealth of resources for construction, not only there, but for Earth satellite applications as well. The airless, low gravity moon makes feasible a safe, quick method to transport lunar manufactured material by rail guns or some by the other electromagnetic transportation means (beam power- Appendix B), as discussed in the Mars section. Propulsion benefits are discussed in greater depth in Section 2.2.9. The remote production of chemical propellants for space missions is another benefit of the moon. Having an adequate energy supply to meet resident lunar mission needs is essential, and fusion is an attractive energy source option, particularly with the presence of the 3He there. aforementioned missions were not undertaken here; it is suggested that some additional study be undertaken to better define the magnitude.

moon, electromagnetically and on the Earth’s moon. wide variety devoted

The primary involve Alternatively, were developed, propulsion payloads endeavor performance.

from the moon or any other planetary moons would for

Although different “How can we transport takes advantage

if the means to produce the advantages of system with a thrust-to-weight

of electrical a high thrust-to-weight fusion would

an answer and safely or, as in the case of

are any which and higher. system fold.

This idea pursues economically resources

a new, to the question, in space?”

energy on Mars to a is being the of

application section examination

to the implementation is the availability

propulsion be multiplied many

of applications, Dr. Logan’s

generic a separate in-depth

thereof. has been alluded

to lift substantial be a worthwhile

concept transmittal supplies.

Because developmental

can provide that power solution.

to this topic which contains

B. Essential through

in Appendix of energy

for 10’s of megawatts

capability to in this

to the lunar mission

FOR SPACECRAFT

Mission Description

the electromagnetic

the local planetary

ratio high enough

seem inherently

of multimegawatt

Fusion energy

objects more

PROPULSION

STATIONARY

the concept’s

to propulsion.

ELECTRICAL

contradictory,

the reasons

requirements

environment,

it describes

discussions

the airless

concerning

title may

approach

of space

(LUNAR)

transport

POWER

report’s

energy

safety,

2.2.11

earlier

stated

power

fusion

space

2-108

AND

lack

The

and

this

the

Lm’I *

and

driven

energy

waves.

system,

17.-’ -.

i ..&,Mr4E NCE IJV E RN)R£ I.AEIO_ATO_Y

propulsion

to consider:

A o01ications

A conceptual

electromagnetic

ion propulsion

for to thrust

system is shown in

rail guns, electromagnetic

2.0 High Energy Mission Applications

using of electrical the laser

an ablation power via transmitted

applications to a spacecraft for a ground-based

via an ion engine, energy directly direct

power for conversion laser system which transfers

There are several transfer of power power electrical to a spacecraft transmittal schematic Fig. 2.55 (Log88).

Fig. 2.55. An economical Earth-moon transportation

—”ooo’o’

remotely powered by free-electron-lasers.

,-Pu,…=.oo

system based on pulsed plasma guns

r_”°‘t_eel ’ /” .

_o,oJ

/ /%C’

Propellant c

(Log88)

2-109

“,2”;k

MM°nnthldY_LCyc_ns%utl/

_r°r’_ys Ceil

.-”

—/

ierlr’_r

Cargo

,nlla,able

I’

M,rfor

\l_l

/#”

Fo,I

Total

2.0 High EnergyMissionApplications

There are advantages to a large source of lunar based power. The airless moon makes feasible a safe, quick method for material transport by rail guns or If we seize the some of the other electromagnetic transportation means. advantage of alternative sources of power, the environmental impacts on Earth launch efficiencies are gained from the utilization of are reduced. extraterrestrial materials rather than to transport heavy materials from the Earth.

Lower overall energy requirements to accomplish space construction projects field and the can be anticipated because of the reduced lunar gravitational absence of an atmosphere. This is a superior scheme in terms of energy efficiency. The reduced gravitational advantage can be used to even greater advantage if local resources are employed for the missions. This subject requires a systems engineering task for an overall evaluation. Lunar resources should be considered a part of any trade wherever space programs on a grand scale are concerned. If we were to advance the lunar materials processing technology to a sufficient degree of sophistication, construction of the reactor’s bulk mass can be accomplished in-situ.

Consider the means by which supplies can be simply transported back and forth to Mars. The source of kinetic energy for the Martian shuttle vehicle can be a free electron laser for an ion engine drive or alternatively, a laser heat driven ablation rocket. can be accomplished by either a surface or orbital based fusion reactor system. The reactor could also similarly be employed to power payloads back to Earth from Mars using the same propulsive system design concepts. These are concepts, the merits of which would have to be given further consideration after completion of system studies in order to determine the economic trade for comparisons with other technologies. The initial program costs would be high, but operational costs would be expected to be relatively low because the propulsive energy resides in a stationary location rather than on a flight vehicle permitting greater efficiencies, and obviously with safety improvements achieved compared to using manned transport vehicles.

The types of missions which can be supported using this concept are manned Mars missions using unmanned transport logistic spacecraft. Manned missions during extended stays on Mars require support by logistic vehicles, the concept being forwarded here being a flight vehicle powered remotely by a stationary energy source. For these unmanned vehicles, the trip time, energy, and cost trades can be made to optimize payload mass. With fusion energy, a broadened capability exists by which space missions can be optimized, that is, we can transport smaller objects to and from Mars by fusion powered lasers and chemical propulsion, and large, massive payloads powered by on-board fusion is equally applicable between the remote moons of energy. Jupiter, for example.

The other key point is that there is a specific power trade which one can make to In the event that the flight fusion reactor systems arrive at an optimal design. flight are unable to initially achieve the high specific power

The anticipated megawatt power

The concept

required for

requirement

2-1 10

2.0 HighEnergyMissionApplications

The lunar power station can provide power

performance, one alternative is the use of fusion energy from a stationary power In an operational mode, fusion source for the propulsion system energy source. as a power supply for a laser driven spacecraft, offers a competitive advantage, not so much in specific power as in offering a potentially high fraction of materials utilization from local lunar materials. This subject is discussed further in Appendix B.

Electrical energy beamed from the lunar surface to Earth orbiting satellites for the purpose of providing electrical power may also prove to offer significant alternative economies since attenuations and aberrations by an atmosphere through which ground based beams must pass are eliminated using lunar energy transmittals. to Earth orbiting satellites for meeting occasional peak power demands or to serve as a steady state supply of energy. An adequate energy supply to meet the power needs is essential for future mission options, and lunar fusion provides an attractive alternative, particularly with the presence of helium-3 there. The it is magnitude of the required power levels was not calculated in this study; suggested that additional analysis be undertaken.

opportunity loss of science science the use of greater instruments Science (Bio78) rate category this capability. performance one in which major mission

Some comment flight times hardware objectives missions, payload have cataloged Unpublished shows objectives years

failure altogether. We have been very successful but

in outer planet explorations, either

be noted. With the greater the increased

are no longer met - as the mission duration

in the highest thus demonstrating

the NASA centers’ life -i.e.,

design margins shown

and the use of more redundancy.

to result equipment,

data taken from one of

on mission success

energy will permit

CONSIDERATIONS

from 3 up to 10

loss in achieving

in accomplishing

the availability

exists causing

the need for

(Fig. 2.56).

spacecraft

MISSION

of more

a useful

data or

involved

duration

reduced

extends

science

serious

should

2.2.12

failure

space

2-111

been

LIFE

for

’

_ ’

”/

‘J

I’

“1 ;’

‘_1

90’

’ met’l

lOO

//\

I-’=’_”-e’/’

1965

3 YR—_/’

themaj°rmissi°n°bJleCti_esarebeing ’

<_ 5o- 4o-’

2.0 High Energy Mission Applications

//,,

1970 LAUNCH DATE

RECORDOFACHIEVINGn YEARSOF USEFULLIFE INORBIT

,,<, >= 8o- z_ 7o- 6o-

20- o lo- o

that up to the time limit of is the prime Science the the life performance of as lesser that can be

since the intent life. There are two points to be life as a that can be taken to

a relaxation slope exhibited negative the current rationale science important

These may have been to last derived function

taken to lengthen requires science power.

improve initial positive slope, presumedly

the payload. as a result of a design learning

for those missions. instruments functions

learned the standards by the 1977-80 interval.

is a degradation there are measures

One approach system capability

from the curves: of mission

where by high specific

life performance. propulsion

by the curve, and two,

an additional instrument

numbers must be carefully

Fig. 2.56. Spacecraft performance

taken as a consequence

as shown Actions

trend show a positive

is increased margins.

base of performance

upon the operational

there are measures

of space missions.

these are typically

can be increased

there and (2)

for a significantly

by the negative

The conclusion

characteristics.

of operational

has endured

is a concern

a subject

slope which

the mission

performance

is exhibited

That the

considered

life history.

duration,

although

payload

function

Further,

treated

shorter

is that

2-112

That

data

(1)

that

could

those

fusion

2.2.13

include

SMALL

SPACE

is most

program

shuttling

FUSION

between

planning

missions

payloads

REACTORS

If developed,

the present,

is the group

on the order

are considering

if even possible

into the domain

These missions

with the present

Mission Description

of several megawatts

Earth and the moon,

the Earth and moon,

between such small

of reactor fall

upon in this study because

see Appendix C. Power of

application by small less. or

2.0 High EnergyMissionApplications

missions in the SP100 these more appropriately

application which into the high energy mission

in the fusion These that the advanced missions (100 kW) and higher fission

One useful mission category which would find an immediate space be accomplished reactors, namely, reactor’s may be very difficult, range would be compatible which range. reactors.

geosynchronous Earth orbit. concept was not expanded space falling however, designs more economies specialized anticipated changes

plus others within reactors would serve as a Space Tug. This time the at are those in the future, reactor reactors will be developed

NASA in the is to but even with remain far out of reach for

decreased made Shuttle Program but essential make it airline-like those extensive the general

of fusion applications terrestrial power stations, can be expected if applications

for favor remote that LEO missions or large beam power

lower found that a large number of ground support

location could be required in LEO were required.

This category for than gigawatt uses

costs personnel had been conducted

likely to fulfill more quickly At some

the some is It large plane

To lower launch thoughts propulsion.

the technology can be developed.

flight operational costs to orbit

although to occur. for

launch costs for commercialization

substantially launch

of space is indicated.

safety the unique

and flight operations.

to the point where

Mission Description

a new technical

AERONAUTICAL

for aeronautical

and to improve

is the use of

the centralized

to significantly

to its launch

of magnitude

transportation

consideration

have to be

in an effort

the present

and safety

to become

commercial

operational

population.

enterprise,

enhanced.

by orders

a serious

forwarded

approach

category.

activities,

to lower

a strong

to orbit,

territorial

If space

One of

is ever

Studies

smaller

evolve

2.2.14

where

fusion

space

rather

costs,

2-113

could

costs

effort

likely

point

for

will

less

cost.

at a

time.

which

Space

aircraft

require

fraction,

vehicles

(Section

because

is totally

transport

Perhaps,

fractions,

reusable;

endeavor

personnel

The cost

equipment

of space?

expensive.

to reduce

to airlines,

to achieve

of simpler,

is serviced

high mass

requirements,

as a commercial

ones Airlines

lift, may possibly

intensive costs

the commercialization

greater program,

The ground servicing

spacecraft, to orbit.

or even more stringent,

is achieved using

ground are needed

they offer a safe product

requirements fusion

in part by a quick turnaround

2.0 High Energy Mission Applications

flight and ground crew per flight.

as for example with the main engines,

Development having succeed

staff readiness approximately

similar to become economical.

benefit The major 8). As an option,

the gross vehicle weight, whereas with the large wide body aircraft,

and system specifications is ever

to launch the Shuttle as is the preflight to orbit comprises the payload delivered

Would fusion energy more distant mass aeronautical

reasonable high payload mass number of of magnitude the Shuttle of 60%. The commercial maintenance demanding operational space flight

and by a by a small is orders In time. 1% it is 50 to the Shuttle is not. The Shuttle are more basic

Thus, far driven by the appealing system can be designed phase would be substantially provide such as turbopumps. hydrogen-liquid Perhaps the safety worthy of consideration.

the reactor would of air to attain the required mass flow for high thrust. supply would occur at high altitudes. this may not be a far out concept when one realizes fission

Earth’s order significant would be a great benefactor. by a couple lowered objective

launched design and safety viewpoint. serve as a heat exchanger Thrust It should that

The use of magnetic require the use of high speed liquid helium for the highly explosive very positive is another

liquid step for safety. at some later point may negate approach

to make such promises that for aeronautical enhanced.

in a are high thrust and low with the aid of from

levels on the highly of space are The air-

fuels may provide a practical review and a detailed

ramjets. and environmental the air prevented

requirements is used. lift a high altitude,

reactor in the launch to

solution study for consideration.

the ramjet performed. product

reaching the commercialization

to be more practical regimes,

high thrust-to-weight safety

be used to transport man and materials

from fission The employment

time it does offer an attractive

in greater depth in Section 9.

the safety to leakage

to low Earth orbit without

is to use a single stage

surface of millions

to orbit or alternatively

does not of

too early thought

or nearly aneutronic

orders of magnitude

is a far feasible,

lower altitude flight

Safety is discussed

where aerodynamic

the United States

for this application.

oxygen fusion

From a technical

had successfully

and radioactivity

be pointed out

in the 1960’s,

if that concept

field hardware

but potentially

in combination

if a sufficiently

to an internal

The vehicle’s

developments

is determined

lift purposes,

of aneutronic

If technically

of newtons.

the present

but one is

combination

Substitution

proposition.

equipment,

conversion

It certainly

propellant

is clearly

However,

viewpoint

problems

deserves

research

requiring

its use.

opinion,

from a

energy,

nuclear

vehicle

energy

but at

stage,

tested

orbital

2-114

thrust

some

lift-off

level

This

that

For

but

for

this

with

This

been

fusion

Hence,

provides

because

amounts

According

Application

is a totally

has never

at a power

is unknown

new concept,

in comparison

and spacecraft

to be extremely

review did not

and a literature

lift must operate

power machines,

reveal any prior

large accelerations

feasibility considered

least not by the design

study of this application.

now being set

that even lesser

2.0 High Energy Mission Applications

the traditional engines.

considered for aircraft operate

Fusion reactors are not high specific

from the lunar surface ambitious

for aeronautical or other for

of high thrust as a fusion requirement.

engines at 1550 kW/kg for example.

for aeronautical on the order of 500 kN thrust.

specific The Space any such lift, or which small planetary The technical

by Dr. Kernbichler (University the plasma would have to be in excess of 3 meters

The power plant produce developed University), produce model. discussed will await

concepts power standards Shuttle’s main engines undertaking provides bodies, must be considered

The reactor design must provide a high specific direct injection exchanger. flow rate to maintain

One additional Section 4, purely aneutronic reactor advanced

and fusion cannot conceptually The reactor must be of a relatively airframe

while in space. structures will become will

alone is not sufficiently for aeronautical too, drag.

it must do so at the mass flow rate, a heat high

to be an optimistic transfer mode, the application reactors.

are: establishing avoiding A high _ reactor design

are unlikely of physics are still neutron emitters,

level. environment particles tritium is used,

program. Without thrust producing, propulsion. successfully

to plasma model Technological in diameter

of multiengines should the development

in for the early The at a very

reduced in Earth’s are activating If

reactor mixing of high specific The means

be considered small size, and to minimize

considered in the thermal Otherwise

require and surrounding unburned the

substantially operating Neutrons radioactive.

reactions due to the inherent

issues the plasma, impulse.

be studied of more compact,

to be developed the reactions

and maintaining is essential

directly From a technical

is the neutron flux. As discussed

into the plasma at a sufficiently

a uniform the required

approximately Use

(see Section fusion

power. of a diluent

the additional mass flow,

from flight care

fuels under consideration

high _ is a key matter

10 kN, and that was

not only a high thrust

radioactive materials

into the atmosphere,

7.0). research

vehicles than

that must be met

aircraft products

are two ways of

into the plasma

the fundamental

a fluid across

extinguishment,

of combustion

and operation

level sufficient

to accomplish

for producing

accommodate

the reaction.

high specific

for a space

a lot more

the means

The diluent

the plasma

to a fusion

view point,

Illinois/Graz

or passing

is injected

integration

at a level

level, but

increasing

proliferate

emissions

feasibility.

challenge

involved.

although

probably

in order

Neutron

designs

design

below,

power

There

2-115

to its

for

that

decay

fusion

2.2.15

is not

further

raised.

concern

to LEO.

Perhaps

A study

an early

limitations

of That

in specific

application

is a subject

transportation

consideration.

of issues

is so attractive

this application

since hydrogen

the attractiveness

to define concept

the fusion powered

from an engineering

this concept warrants

requiring more research.

In summary, to orbit

aircraft may be a solution

of a high payload capability,

energy. is necessary

2.0 High Energy Mission Applications

power and thrust conversions,

the hazard may be acceptable,

be in a range that can be handled

D-3He may possibly viewpoint.

using a single stage Without

exclusion. the magnitude tritiated water.

and landings may possibly from

of high payload mass fractions,

Takeoffs rapidly, and the neutron fluxes

is light and tritium is a weak beta emitter, being the main

Flight operational the environmental some of be limited to remote sites. Neutrons

breakthroughs into this subject, considered including feasibility. The goal of the program is to provide a safer, high payload mass fraction means of

This particular can be made toward by flight experience very safe, contributions existing compare waste disposal. radioactive such nuclear waste disposal missions questioning,

from the to based Space has been costly to access and the safety of to heavy On the

fission cost and safety merits of Earth based and space

becoming more difficult their back yard to be an attractive

powered to space, perhaps of disposal

that progress and if the opinion is verified

where a safer, more economical means for transportation

aerospacecraft one of radioactive

reliable mode for travel will be to provide

in space will certainly the Challenger

to find. No one finds a nuclear waste disposal

the risk affiliated processes

even more so now in view of

commercial the relative

of and leaching

other hand, disposal

aeronautical fusion that

circumstances is achieved

Space offers an attractive

be subject accident.

have been conducted

facility alternative

the most significant

Mission Description

is very speculative.

in Section 2.2.13.

fusion propulsion

there is always

and locations

under to orbit

in the event

as discussed

particularly

underground

earthquakes

DISPOSAL

REACTOR

suggestion

a concern

propulsion

FISSION

WASTE

feature.

Studies

provide

plants.

debris

power

space

2-116

But,

with

are

for

and

The

One

data

large

lunar

been

these

would

power

based

2.2.16

earlier,

energy

various

surface

is that

Mission

BASED

referred

facilities

systems

POWER

sections,

program.

concepts

Electrical

factories.

to move

extracted

purposes

of Local

capability

Planetary

propulsion

is a lack

for space

from the

generation

Resources

application

it seemed

propellants

consolidate

appropriate

significantly

and which

and study.

their own.

of analysis

FACILITIES

on planets.

investigation

Desq_riotion

is a subject

from those

requirements

of Arizona’s

Space-based

and provide

AT SPACE

Manufactured

to run lunar

the chemical

ELECTRICAL

about which

As discussed

of propellants

to throughout

little attention

into a category

by the University

the manufacturing

there received

to have have

aid the performance

propellants is a topic

assumed applications

is therefore large

for propulsion Utilization

2.0 High Energy Mission Applications

low specific simply after

fuels propellant and settlement

just On Mars, by the space

are exponentially fuel supply

high an atmosphere

by Dr. Logan in laser

the vehicle’s stay

its deposition source

the vehicle’s are

conditioning. transportation

for atmosphere.

efficient propellants.

temperature for

transporting the

extract to provide

breathable attractive

(Appendix which

and for manufacturing

permitting as that

fuel and propellants

This available

chemical oxygen

been involves

amount chemical

provide missions

can be anticipated

from one location

moon, maintain

the fuels whether

well It could

return a large

to this latest

beam microwave

a large appetite

be a necessity

from elements

or space-based

to be required

to the subject

and materials

are inefficient,

and magnetic

a breathable

environmental

to spacecraft

new version

a substantial

a sufficiently

field, serve

consideration

low energy

An is to

to constitute

implemented

for energy.

for making

gravitational

to another.

atmosphere

in reduced

capabilities.

and which

to process

a science

for mining

operational

propellants

idea was

technology

processing

consuming

a simpler,

production

be found

propulsion

fabrication

or space

generated

B). not

has look

propellant

of power

technique

extraction

therefore,

quantities

Helium-3,

in terms

outbound

capability

by solar

of mass

extended

purposes

retrieving

helium-3.

the way

outposts.

providing

desirable

functions

program,

available

refueling

explored

of ores

A more

as well

enabling

resulting

on any

Sources

systems

furnace,

involves

requires

asteroid

capable

(Log88)

copious

stations

thinking

support

by the

quicker

1960’s.

subject

include

energy

means

Fusion

having

should

in the

winds.

found,

recent

obtain

power

rocket

power

fusion

could,

in-situ

2-117

Other

along

of a

when

given

times

costs

there

lacks

data.

been

large

likely

have

body

laser

solar

layer

After

flight

local

That

than

ores

dust

This

field

new

was

The

and

that

and

can

first

this

the

will

life

for

is,

result

return

on to

power

2.2.17

station

energy

vehicle

periods

science

Greater

OTHER

BENEFITS

to produce

in Sections

The higher

for cheaper

1.0 and 2.0.

the capability

could provide

to space will

more massive

beam to transmit

12 MT to the moon.

a translunar manned

to conduct more extended

of delivering surface

power transportation

2.0 High Energy Mission Applications

A multi megawatt payload

of additional levels will shorten

as flight of scientific

from the availability thrust

free electron capable the lunar Mars.

New benefits discussed times and provide exploration.

a highly advanced real by robotics. provide changes effectiveness.

Because planets, more wider analysis. large,

A large inexpensive capability system

1022 kg of 3He are estimated By a clever

Uranus: a high energy economic Neptune

of for This is a mission

to reside in the atmosphere cycles

and to perform hardware cost and quickly

Jupiter: Jupiter. liquefaction, requiring

from the from a to Earth for

application of this yields a net

can be returned allows

to the moon there are other sources

system mission to Uranus. Whether

and decision making with decision

payloads samples which

energy to repair upgrades

The additional stationed

the enabling flight

These could be unmanned

In addition more difficult

a large power capability.

of 3He may be possible.

payload laboratories.

of 3He is one potential

range on the surface

have been obtained

is also a possibility.

Helium-3 Mining

has the capability

one to consider

for expenditures

and equipment

The possible

for helium-3,

and thermal

is a subject

the recovery

time in-situ

of balloons

and larger

to retrieve:

be carried

intelligence

of artificial

exploration

but much

execution

capability

recovery

remotely

analysis

to and

degree

benefit

source

design

further

study.

2-118

with

and

can

for

In the event

Asteroids and comets

2.0 High EnergyMissionApplications

There are, too, some far reaching, but practical, applications of high energy. If a large asteroid or comet were to approach Earth, revectoring the body via a high energy source would be mandatory to life, as theorized by the periodic life avoid a catastrophic loss of extinctions. Smaller ones are more frequent

in 1991 Earth was narrowly (~100K miles) missed by a small one having the destructive potential of an atomic bomb.

Another high energy mission application is the use of the comets as a natural resource. They offer the potential for a natural supply of water for planets where the addition might be needed, as for example, Mars or the moon. Although it is too early to do little more than speculate regarding the vitality of the asteroids as a source of space based minerals for functional space use, that application could become an important aspect for space exploration. The first task is to characterize asteroid’s composition. rare or greatly needed elements are discovered, it may be economically feasible to provide the propulsive means using a high energy vehicle to transfer the asteroid intact to the moon, Earth orbit, or to Mars for convenient extraction of ores. All of these missions require the expenditure of very large quantities of energy plus a significant amount of time.

concept, reactor serve to power trade would favor of structure are used in the space construction

could the economic there as well as the fabrication where large masses

The moon, Samples extraterrestrial moon. manufactured The absence sources

facility. of having on the or the Earth. from such to conduct

could serve as a valuable particularly

remote any suspected in great

upsetting wind currents earlier,

experiments and isolated products

can be designed Perhaps

hazards be an ideal spot

biological controlled engineered

for use here on Earth could have

to burn it, at some point,

the effects Thus, some of

from the moon and if the terrestrial

there without of convective

be analyzed chemicals

the delicate reduce

environment global

to examine conditions.

is made to mine helium-3

the lunar mining facility.

under genetically

now being considered

COMMERCIALIZATION

could be researched

Mission Description

If the determination

the manufacturing

of all categories,

the controversial

and equipments

AND SAFETY

APPLICATIONS

As mentioned

the tokamak,

or potentially

if developed,

then fusion

of materials

engineering

of genetic

Dangerous

particularly

quarantine

dangerous

life threat

materials,

planetary

potential,

of other

to zero.

projects.

it would

SPACE

2.2.18

safety

2-119

that

could

prior

least

been

safely

fusion

power

2.2.19

already

EARTH

Applications

benefits

qualified

could at

ORBITAL

Avoidance

to consider

catastrophe

of this section,

receive further

offer significant

APPLICATIONS

at the beginning

2.0 High Energy Mission

of some biological

Mission Descriotion

to use on Earth. With

are low energy missions.

comparisons typically

those advanced mission concepts

however, where it could be useful

Large out of plane LEO maneuvers

study on Earth would in

systems these LEO applications, capability.

high to LEO missions are some There a high

available, for consideration. itself pay for fusion and the space program.

As shown by the performance do not performance since most of applications possible performance

energy Earth thereby mode in the event of a loss in power.

to GEO are also can be placed there and serviced There

electrical to meet peak demands spacecraft

rescue high to provide to be a fully dedicated

Space Station Freedom, potential exists remove the debris.

spacecraft vehicle. expended performance spacecraft.

is possible, spacecraft, that provide Earth orbit.

based to any of a large number

A high energy beams orbiting

EVA astronauts, for use of a high energy

observing to desire to low

and other spacecraft. spacecraft

placed in low Earth orbit could also serve as a

require large velocity a single

the thrust response. i.e., a space

reduce costs or to serve in an emergency

it be translatable the desired

for changes ground coverage

personnel sufficiently necessarily

a GEO debris be used

in orbital after placement

in order into an initial

the cost and mass of which

that a rapid vehicle,

of A high GEO

This ambulance,

be at a is not

to cause could

large logistics

by a high energy

A high energy

that LEO debris

to economically

for example,

can become

can transmit

the eventual

very energy

is sufficiently

accumulation

large Earth

requirements

Missions

to remove

demanding.

Similarly

is concern

operational

to reduce

spacecraft

inclination

a hazard

assuming

regarding

of and

changes.

problem.

to build

back-up

vehicle,

derelict

vehicle

station

Single

power

space

2-120

there

great

level

their

The

can

for

but

any

and

one

The

also

their

such

have

plant

place

could

serve

those

future

power

2.2.20

supply

growth

benefit

natural

routine

reactor

Station

smaller

serving

a dual

viability.

It could

As with

function.

missions

research

servicing

feasibility

biological

economic

determine

spacecraft

practicality

at Space

the Earth

technology

spacecraft.

and repair

SPIN-OFFS

will greatly

suggestions

atmospheric

experiments

be studied

revitalization

performance

development

long duration

for unmanned

as an orbital

and Large

a multimegawatt

orbit application.

be accomplished.

perform and

to serve scale

materials sustenance

Freedom maintenance

manufacturing functions.

2.0 High Energy Mission Applications

in ground to a point where

A number identified benefit

to the original there

be significant. programs

is the Manned Mars Mission

missions could of

been be of great

can high energy

new high energy mission

systems, be applied

where and which

the high energy mission

there will be technology

The the space

if magnet train

high energy missions.

result technology

high particularly

in launch enabled

be held to explore

savings missions

and the terrestrial

now if available.

energy, be

be in a position

fall out without

in improvements

and to provide

regard Clearly

to high speed

to complement

is to establish

the shortened

time can be

are frequently

intent. for

of potentially

and develop

transportation

to contribute

high energy

a substantial

unanticipated

from space

The Fusion

is advanced

applications.

One would

applications

benefactors

is potential

significantly

SUMMARY

technology.

an optimal

appropriate

operational

disciplines,

conversion

by fusion.

particularly

workshops

in greater

Workshop

“spin-offs”

and any

concepts.

important

Improved

scientists

expected

attractive

materials

program.

consider

to flight

Perhaps

program

greatest

Science

benefits

function

it could

Medical

science

Mission

energy,

forward

Equally

derived

Energy

in the

energy

other’s

should

Space

depth.

areas,

where

result.

safety

space

fusion

space

fusion

would

costs.

2-121

other.

many

could

other

class

each

have

used

flight

High

One

high

Two

fully

The

and

can

are

2.3

the

for

the

2-7

are

can

that

and

The

2-8.

with

high

data

MT),

flight

outer

using

those

Table

within

would

return

times,

fusion

tables

fusion

These

(20/10

Space

values

further

Tables

kW/kg.

energy

vehicle

include

powers

planets

specific

ranging

mission

(133/61

masses

impulse

asteroid

reactors

Manned

reduced

seconds

variable,

a viable

presents

program.

seconds.

comprise

designed

planetary

missions;

2-7 and

Applications

Workshop

parameter

is specific

for space

the times

conversion

in Section

exploration

reasonable

10 kW/kg

parameters

to specific

key fusion

summarized

velocity-high

performance

for Manned

key mission

from 5,000

of 1 kW/kg

(20/10 MT,

Av missions.

complemented

power which

are discussed

and penalties

in establishing

for Table

3 to 6 visits)

and propellant

be instrumental

outbound/inbound

be accomplished

times flights.

typical missions

Mars sample

of merit outer

system exploration

The Missions

kW/kg missions,

2.0 High Energy Mission

from 3.5 to 5 years.

the solar above

minimal economical

to achieve associated

and figures payloads),

initial 2-8 summarizes

using to 150 and 240 years

and Oort Cloud be

seconds. or propellant.

could a rendezvous

be reached mode,

quantity respectively,

and to a manned

Performance payload,

but at an enormous

force may perhaps

of and application

sample referenced

in a fly-by mode

131 MT outbound/61

of 20 MT outbound

Alpha Centauri

and 10 MT return.

system is not

and settlement

in consumption

in 180 years,

years Those

of stay durations

a reasonable

be decreased

understanding

of propellant.

times exclusive

in times

be of value

as currently

a variable,

envisioned.

are the total

the stellar

exploration

be above

the solar

A deeper

Performance

capability

MT return

nucleus’s

the target.

= 1 kW/kg

The times

increase

unmanned

impulse,

Manned

in 290

Asteroids:

feasible

Av, km/s

ranging

specific

missions.

beyond

planetary

summary

regard.

payloads

in that

Pj, MW

should

seconds

35 680

35 130

26 200

26 120

Manned

manned

Miranda

asteroid

10 610

40 530

18 550

16 690

strong

Specific

power

Mission

fusion

3 visits

6 visits

Charon

2-122

Europa

sample

TABLE

could

using

return,

shown

typical

must

<lsp>,

power

return

Triton

Mars,

then

years

high

very

2-7a.

outer

tf, %

Titan

Mars

The

flight

0.50

1.56

2.99

5.34

1.72

7.42

3.39

5.85

data

the

335

320

254

108

233

185

317

196

Mo,

Mp,

for

are

6.3

for

4.1

3.8

3.4

5.3

6.8

are

317

233

209

185

and

data

3.39

1.72

7.42

5.85

5.34

2.99

1.56

0.50

flight

Mars

Titan

_,, %

outer

2-7b.

times

Mars,

Triton

typical

shown

57,020

81,180

64,070

35,770

TABLE

sample

Europa

Charon

6 visits

3 visits

Mission

Specific

asteroid

Miranda

Manned

manned

137,069

129,620

117,509

Mo, MT

payloads

Mp, MT

summary

exclusive

planetary

Asteroids:

unmanned

the target.

Av, km/s

a manned

The times

Pj, M W

MT return

Applications

Performance

t, years

are the total

return, to

return missions.

of stay durations

<lsp>, seconds

and 10 MT return.

power = 10 kW/kg

of 20 MT outbound

131 MT outbound/61

sample referenced

2.0 High Energy Mission

Performance payload,

and to a manned

Performance payload,

131 MT outbound/61

sample referenced

of 20 MT outbound

for a fast manned

power = 1 kW/kg

return missions.

of stay durations

10 MT return.

are the total

Performance

The times

MT return

the target.

unmanned

Asteroids:

planetary

exclusive

summary

payloads

seconds

25 780

28 570

20 300

22 860

Manned

Miranda

asteroid

14 600

17 750

Specific

Mission

6 visits

3 visits

Charon

Europa

sample

14,720

86,735

shown

return,

<lsp>,

2-123

Triton

9,440

1,031

1,041

Mars,

years

times

2-8a.

outer

_, %

Titan

Mars

M W

flight

km/s

11 7

5.49

1.44

2.82

2.11

4.59

0.44

1.43

3.48

12.8

data

217

223

301

677

797

852

992

116

976

687

895

809

733

858

329

and

Mo,

Mp,

Av,

are

2.1

2.0

2.5

2.0

1.9

2.3

Pj,

8.4

2.2

609

171

237

464

670

796

112

437

352

2.76

0.65

0.18

1.30

2.87

1.93

1.20

0.81

12.9

Titan

2,225

1,034

1,119

Triton

return,

18,870

79 820

Europa

Charon

42 210

30 920

Mission

50 650

70 134

63 300

Miranda

Mp, MT

Mo, MT

Av, km/s

t, years

— 10 kW/kg

to a manned

Manned Mars

Specific power

1’, % Pj, MW

<lsp>, seconds

Asteroids: 3 visits

Asteroids: 6 visits

summary sample

and 10 MT return.

Performance and asteroid

2.0 High Energy Mission Applications

times exclusive of stay durations at the target.

unmanned The times shown are the total

TABLE 2.8b. sample referenced payloads of 20 MT outbound flight

for a fast manned Mars, outer planetary data are Performance return missions. 131 MT outbound/61 MT return payload,

2-1 24

43 920

1,053

631

2.5

for

3.1

HIGH

ENERGY

including

programs

SOURCES

3.0 HIGH

in the end,

CANDIDATE

acceptability

performance,

such factors

FOR SPACE

disadvantages

The significance

It is not sufficient

and the performance

the cost effectiveness

its mission enhancing

levels were presented.

in the accomplishment

In Section 2.0 candidate

total program risk reduction

to evaluate risk reduction approaches.

In this section we examine the candidate

the selection of any high energy source

of the system on flight operations, effects as environmental

is to investigate the means to provide a new of high advanced missions requiring space of high energy their requirements energy and

Major considerations mission enabling capability, implications, overall reliability. only slight improvements performance inherently enabling and enhancing instrument; increase will not. Hence,

One study objective, approach for performance missions. high energy missions for future achievement were analyzed. sources for performing those missions and discuss the relative advantages

interwoven part of this (Section 10) became an integral, (Section 2), and cost study. are the Two other critical aspects of high energy source acceptability degree of safety or magnitude of the hazard which is offered and its kindness, or hostility, The means and for converting the energy sources into propulsion and power systems feasibility in Sections 7 and 8. are discussed later and,

include its the safety and and that high energy missions be accomplished with A cost effective, high compel as a mission a system providing a slight performance (Section 3), mission performance

Consider accomplish applications the flight system must:

systems placed into space to In those

for the expenditures committed.

to its operational environment,

the kinds of missions

on energy conversion

topics of Section 9.0.

its development

the demands

system will

in Section

discussed

for fusion,

sources

energy

2.0.

3-1

for

and

long

meet

thrust

power

despite

specific

impulse

variable

vacuum,

of years,

propulsive

operations

a lack of

environment

system mass,

provide power

provide greater

(low thrust-zero

levels (throttable),

provide a remote,

With consideration

minimize propulsion

in a low acceleration

inherent system safety,

Flight system properties:

be designed maintenance.

provide requirements,

use only radiation for cooling,

loads (zero thrust-zero gravity),

for the generation of electricity,

long system life time requirements

3.0 High Energy Sources for Space

produce a very wide range of output power

reliable, and efficient space restart capability,

be designed for the presence of a ‘_ree” continuous

to operate be designed gravity) or in the absence of gravitational

for the of magnitude. better while matter-antimatter

Relative 3-1 (Bor87), (deuterium chemical comparison over

yields excluding and (hydrogen

in Table fusion best In is

from the above energy strange matter.

are compared release over

strange matter
others.

two orders of magnitude

to be an improvement

by nearly 7 orders

with fission (235U),

sources discussed

it is only slightly

potential source

matter-antimatter

fulfill include:

and oxygen)

that in this

The specific

an examination

than fusion.

to the above

requirements,

requirements.

is discussed

is shown

was made

helium-3)

chemical

sources

greater

energy

fission

source

fusion

options

access

energy

source

below.

report

ready

those

could

Each

best

3-2

The

the

for

1.35

8.20

3.52

x 107

Fusion

Fission

x 1013

x 1014

x 1016

Mission

These

of Av,

Chemical

_SPECIFIC

expressed

TABLE 3-1.

comparisons.

are shown

the energy

to consider

requirements,

Matter-antimatter

ENERGY, J/KG

ENERGY SOURCE

Specific energy release

advanced missions.

3.0 High Energy Sources for Space

TABLE 3-2 Typical mission velocity requirements

it is useful the more typical

For space missions in terms for Table 3-2 (Gar 88).

The propulsion, (IUS- a solid propellant km/s to a 1000 kg mass; With staging, core fission, seconds The maximum Av is ~20 km/s from this technology. under 65 km/s in the near missions with Av’s from 90 to over 15,000 km/s.

thermal nuclear The Inertial Upper Stage of 5.2 imparting for 7.6 km/s. The solid of 850-900 of materials. do not operate of yielding This study examined

capabilities propulsion stage) the liquid propellant for chemical

of thermodynamics term and 115 km/s in the far

propulsion is limited to a specific

the upper to be safely operated,

the electric powered

LEO to 1000 AU (50 years)

due to the inherent

system is sufficient

and are considered

LEO to Alpha Centauri

Earth surface to LEO

LEO to Neptune orbit

LEO to Earth escape

LEO to solar escape

LEO to lunar orbit

LEO to Mars orbit

(impulsive burns).

the limitations

of chemical,

and nuclear

Ion engines

the thermal

LEO to GEO

considered

is capable

(29.9 years)

properties

limitations

a velocity

(5.0 years)

is 20-30

(50 years)

(0.7 year)

(40 days)

capable

impulse

Av, km/s

authors

(7 days)

(NEP).

30,000

km/s.

term.

limit

13.4

85.0

3-3

8.7

7.6

4.2

3.2

3.9

5.7

for

will

the

3.2

can

and

cost

and,

flight

have

Also,

using

offers

fusion

power

fission

unless

sense,

Fusion

energy

Rocket

termed

a very

thermal

specific

another

impulse

if more

of man

sources

concept

“Fission

logistics

systems

FUSION

sources,

of those

systems,

chemical

presence

ambitious

Fragment

promising

Livermore

approach.

generated

to space

prohibitive

implement

interesting

propulsion

suggested

(Lawrence

how they

the plans

technology

has been

operational

is nature’s

Laboratory)

now being

by Dr. G.

We discuss

and nuclear

transportation

below each

in a practical

be of benefit

supply high

are developed.

provide will

space missions

for a permanent

on Mars. While

a new approach

system specific

the become

Clearly acquired

Chapline Concept.”

be to to even

are to be conducted

a practical status,

Fusion the stellar

the mission, high

sense and limitations.

3.0 High Energy Sources for Space

program was commenced of abundant,

The national has one purpose

chemical/gravitational tens of millions

is capable of matter-antimatter

energy the production

power. a low funded

The program commercial

is no space existed

by which It is efficient.

concept might have space

to be at high multimegawatt

is a class either

The DOE technology

A. application

energy conversion

of which some

in the 21 st century.

for in terms

of large continued

electrical although

that are anticipated

no other energy

The sun has used

is to show clearly

missions energy

that solutions

are too impractical

and which is its

content wherein

levels possible

flight programs

key conclusion

the importance

which evolved

the background

and the space

in the conduct

energy Lewis

energy or

was cancelled

BACKGROUND

choice have

five. Without

of this study,

of performing,

There which

the chemical

fusion at

is described

in Appendix

by economy

A discussion

the process

and current

for 5 billion

The energy

for another

it effectively

is predicted

to NASA’s

It presents

conversion

and status

for billions

the fusion

proceeding

to operate

to endure

and safe

processes

by fusion

feasibility.

estimated

reactions.

program,

in 1952.

estimates

Research

of scale.

of years.

show it

excluding

produced

in 1991.

for only

program

product,

technical

requiring

missions

furnaces

uniquely

program

it being

primary

of high

release,

of cost,

benefits

strongly

perform

follows.

release

Center,

energy

cheap,

energy

activity

source

a sun

It can

fission

levels,

a few

based

years,

power

There

power

space

fusion

which

serve

been

3.2.1

time,

One

gain

high

total

can

has

the

3-4

the

its

(2)

(1)

the

The

result

that of

program

uniquely

combine

between

research

terrestrial

one that

and, Both

throughout

a strategy

differences

determines

the report,

and offers

the current

are provided

the terrestrial

its availability.

design must

to the space

is independent

first determines

the applicability

power program.

program initiative

for Although

for a new research

the two organizations.

rational fulfillment,

fusion applications.

the top level considerations

3.0 High Energy Sources for Space

many rationale are:

application; therefore, factors

fusion program does not necessarily

there are different mission objectives

agency’s given to research

differ differences the reactor

priority on the technology.

applications Mission which commercial

from the commercial in significant reflect.

second the program commitment to determine

there are significant mission performance NASA and DOE, and

The space power system requirements successful terrestrial the successful experiment, provide but situation which may occur emphasis That

The NASA hardware those made for the ground based utility reactors objectives, requirements, Even the fuels and reaction

from including: mission and program and costs. the two different

program are being obtained Although those more difficult the conclusions

and the results than the program participants has

from the terrestrial would than is the

funding-constrained resources of alternate occurred

of The terrestrial can be expected, when breakeven

as DOE focuses at situation

more energy have envisioned, rationale

greater that the timeliness

forward; the is a reduced

of difficulty are being resolved.

program’s mainline is demonstrated,

critical the expense has indeed

status of the fusion program is described

in a equate to

physics may differ as a result of

application the tokamak,

to press Unfortunately,

differences Therefore,

for applicable

toward the production

will not have space

system performance

for space missions

to be the casualty

can be anticipated

The demonstration

from the tokamak

flight applicability.

and experiments.

This undesirable

fusion to space.

the technology

encouragement

and incentive

in this report

on potentially

The technical

of net power

psychological

the degree

applications.

approaches.

confinement

has turned

undesirable

anticipated,

concerning

of a very

in Section

controlled

terrestrial

reliability,

demands

problems

STATUS

originally

in 1991.

research

situation

program

in detail

different

reached

desired.

a great

funding

In part

difficult

safety,

to be

trades

fusion

useful

space

fusion

3.2.2

been

quite

than

later

task

8.0.

3-5

out

for

its

3.0 HighEnergySourcesfor Space

It would, therefore, be difficult and ultimate demonstration of net fusion energy. to accurately project a schedule of success for a space fusion program, although the report offers a suggested schedule in Section 14. However, the large body of experimental, analytical, and computational tools developed for fusion program provide a good degree of understanding. Those the terrestrial points are developed later in this report, Sections 7 and 8.

Since fusion for space applications has not been under serious consideration by NASA, no major space fusion flight vehicle system studies have been conducted. As with any venture, costs are a major consideration before proceeding with implementation of an activity. Without a demonstrated fusion system, NASA lacks any valid means to establish dependable cost figures of merit. An inertial confinement approach was recently examined (Section 2.2.1), that being the most recent study conducted in the fusion technology for space (Ort87). Detailed system studies are eventually expected following positive developments in the terrestrial fusion program, but not in the near term unless some earlier decisions are made regarding the implementation of a space fusion program. NASA is currently operating on the principle that once the terrestrial energy program has completed the basic technology, NASA will commence developments in fusion for space using the terrestrial program results. By this strategy, however, much valuable time will have been forfeited; and the critical space issues still remain to be addressed. There will still be the need to develop a space reactor since the terrestrial design is not expected to apply to space.

The common energy denominator in advanced mission planning is currently to rely on chemical systems, or, subsequent to the commencement of this study, fission energy sources. Based upon our current state of knowledge of physics, however, fusion is theoretically the optimal source for engineering high specific energy fuels and will remain so for quite some time. Chemical systems, although they have serious performance limitations and safety concerns (Section 9), prevail since these systems are developed and are readily available. The attraction of fission is its higher performance compared to chemical systems and the fact that it has been demonstrated to operate in the propulsion mode. There is a major penalty for continuing to rely upon these systems however. The development of space fusion is, therefore, absolutely if we are to accomplish man’s dream of the exploration of the universe crucial It will not be quick, nor easy, and the beyond our current visionary limitations.

Thus, fusion energy in space may not be determined as much by the mission user requirements, i.e., terrestrial versus fusion reactor design and test space, but by the hard results of a successful program to demonstrate that man can provide a machine capable of controlled fusion such that it will have a meaningful application to space. It will also be determined by the economics of the operating system, the subject of Section 10.0.

in the final analysis the use of

3-6

international

3.3 FISSION

even assume

3.0 HighEnergySourcesfor Space

these more advanced missions

goals of implications, as discussed later, Section 11.

Two types of confinement techniques are being researched: magnetic and inertial confinement. This report places emphasis on the magnetic confinement ICF is too classified to explore openly although we can state several approach. key issues. The performance characteristics of fusion are elaborated upon in Section 5.0.

Fission has the advantage that propulsion has been demonstrated and small reactors have been flown in space. Fission will at least provide an intermediate Perhaps fission can power level up to approximately several megawatts. exceed those levels in space flight systems, that has not been but demonstrated. All fission machines carry the concern for the overall public safety due to the potentially severe radioactivity hazards and the effects on Earth’s environment. Extensive measures are currently employed to ensure release of that power plant accidents are avoided to prevent the inadvertent radioactive materials into the Earth’s environment. For flight systems, system safety measures impose performance restrictions. The public will be reminded of the Chernoble and Three Mile Island accidents, and the loss of Challenger. In addition, the public will be reminded that These accidents beat the “odds.” Russian and U.S. reactors have reentered the Earth’s atmosphere. A public perception will have to be considered and properly addressed prior to use.

In summary, including an ion engine flown in space as an experiment. A reactor can be safely placed into LEO although there is an extensive launch approval process the propellants, can be retanked in orbit involved. for is not reuse replenishable.

is too low for From flight operational perspectives, the category of missions considered in this study to effect the savings offered by fusion or even to perform the missions which fusion is capable, as discussed in Section 2.0. The size of reactors becomes large - 100’s of megawatts which is

technology kW reactor. time for the same payloads having the same Significantly greater mass in LEO is of the

Several initiated or proposed as presented below.

much larger development Accomplishment Mo as fusion required,

fission energy conversion approaches for propulsion have been

The system’s consumables, for short

researched. on the SP-100,

testing of reactors and ion engines,

is not possible using NEP.

there has been extensive

It uses large quantities

the NEP performance

duration missions

than the designs

of the same flight

Current a 100

and the result

PROPULSION

ELECTRIC

performed

NUCLEAR

is being

is longer

currently

although

times.

fission

(NEP)

3.3.1

level

flight

fuel

the

3-7

for

those

should

supply.”

It does

requires

solution.

systems.

therefore,

anticipated

by fusion.

capabilities.

the sample

be required

performance

requirements

the thrusters

improvements

in comparison

with chemical

offer mission

than the life of

return missions,

beyond level

disposal of

in LEO, although

stored cannot

thereby life of

above the current

A not were

reactors and thrust

to be about 10 yr.,

(Gar88) in LEO,

Launch to reuse,

be safe. With respect

Because replacement

for NEP. Even for Jupiter,

parking of an the

accomplished are

thrusters will, power

3.0 High Energy Sources for Space

shown in Table 2 [12,000-15,000

restricting these reactors

of reactors be a satisfactory

the supply of which is not established

safe orbit should unlike RTG’s,

in a high, nuclear reactor,

twice as long as those smaller

and may not be available. Jupiter, were

is life time limited, ‘q’he operational longer

its use from the long duration is expected

sets of in the nuclear be simply and/or robotic is to totally dispose

hours]. Multiple energy reactor remotely alternative than the reusable

to fully utilize the the of the core The the entire vehicle which is less cost effective

There is a safety hazard from the presence it unactivated reactor missions. 6-8 times

noble gases, large number practical 2 orders of magnitude Even then NEP can only perform a mission that accomplished payloads

For missions limited to the moons of Jupiter and even there, a significant remains. Titan requirements are not

this been in the 1970’s due to the lack of

a mission (Section since the project was worked were demonstrated

level of chemical propulsion parameters

20 years have elapsed systems

The NERVA engine technical

Above approach demonstrated.

return missions It exceeds

high thrust had demonstrated

thermal of approximately

in Fig. 3.1a and 3.1b) program

is “developed” fission

in this report, NEP appears

(shown the time of

from life Those

is the best developed,

and the performance

and life expectations

systems, having

refueling of

the major engine

to yield a specific

(Xp0.067 missions.

The performance

the performance

level considered

This technology

was terminated

for power,

at 7.6 MW.

850 seconds

on. Nuclear

and beyond

ion engines.

So although

the energy

the sample

termination.

Propulsion

propulsion

purposes.

challenge

feasibility

technical

systems.

Thermal

exceeds

required

Nuclear

fission’s

impulse

beyond

levels.

safety

to be

3.3.2

level

2.0).

and

3-8

for

—_

I J

Sta.

0.00

__ _

Tank

Pump

Cc_]-

r}ia.

Engine

Gimbal

Shield_

Exhaust

_3% of

Interface

f-Nozzle

lurbopu,,p

1.34 m Dia.

4.69 m Din.

Turbine Control

. 2.24 m.,

Turbo- Pump

Power Valve 7

eactoF— Efflux

,F_-.o. 58 *

Propellant Lines

_----“L’T_GTa—”-; “_Turbi ne Tank/”

3.0 High Energy Sources for Space

and Pipe (Carries Entire Hydrogen Flo,1) (100_,)

schemes which require a large number For probes

in the solar system where there is no this engine could

Although systems, from the emission

chemical result core, and a

the operational particles,

locations from an errant

disadvantages a radioactive

NERVA hot bleed cycle schematic.

cool down system required

exhibit have all of

Fig. 3.1a. NERVA flight engine.

by the need for complex

cooling pulses. threat

systems inherently

b2.9;mOia.

complex reactor

an open fission

are complicated

is a suggested

for maintaining

: IOO:I

improvements

the structural

these they

to the outer

be particularly

performance

is illustrated

environment

integrity of

in Fig. 3.2.

the core

GASEOUS

REACTOR

radioactive

fuel cycle

operations

to Earth’s

of cooling

returning

thrusting

Fig. 3.1 b.

beneficial.

concept

exhaust

“burns,”

system.

reactor,

having

CORE

Flight

3.3.3

core.

over

This

The

that

3-9

(97_)

Beg

Feed

Shell

Coolant

Prelture

Radiator

Uranium

Hydrogen

Moderator

Passage,,-

Porous Wmll

Opllonel Space

3.0 HighEnergySourcesfor Space

Fig. 3.2. Fission gaseous core reactor concept.

over 20,000 C. The temperature 1,500 performance

Space Station Freedom. be expensive Earth’s

concept if it can be verified to be practical.

Aerobraking transportation exhaust could deposit

to be a very the uranium plasma is a

utilized as the propellant core using magnetic

and this engine would the

for a simpler, this is a very attractive

systems by from above 4,000C to

system The it or on the

safer concept. For example,

Fission them out of a very

can be eliminated vehicle.

Safety to test on Earth

This concept difficult concern.

use. and lunar surfaces

is a high thrust, reduces

is a significant in a manner

It is anticipated of

thereby on the Martian

The Fission potential

thermal temperatures

The material employing

concern that would

inherent with the nuclear

has not been researched

by guiding The

a gas core approach,

will be radioactive,

to safely develop.

Performance-wise,

of approximately

The advantage

new technology

which makes

environment.

FRAGMENT

low density

are directly

nor tested.

radioactive

is reduced

to specific

mentioned

significant

fragments

limitations

permitting

high Mo.

restricting

impacting

Fragment

ROCKET

to 6,000

seconds.

FISSION

impulses

products

seconds

equates

Stability

permits

wastes

Rocket

engine

earlier

fields.

which

avoid

times

3.3.4

short

3-10

and

has

trip

will

our

any

that

The

high

star,

yield

solar

rapid

effort

years

admit

thrust

about

Alpha

stage.

fission

system

specific

to find

Specific

keeping

payload

exhaust

or very

analysis

(Cha88)

seconds

impulses

fragment

payloads

Centauri,

velocities

a variety

indicates,

a million

significant

interesting

We hope

conceptual

The work

preliminary

a hundred

acceleration

be required

is at a very

to guarantee

the optimum

is insufficient

to be we

levels. of

The proposed

light to the

of approximately

must specific

of masses

system transport.

while maintaining

proves although

very impulses

percent missions,

on a very preliminary

parameters analysis.

are based studies

respectable allow

upon performance

and enable nearest

reported Considerable

the velocity e.g.,

the optimum as attractive

in this paper trade-off

in the form of 5 mm diameter

3.0 High Energy Sources for Space

fissile material and propellant.

this magnitude several

system. as our preliminary

limited level of performance.

for use on this mission of commercial

at 10 tons with more the rocket

tons in 101 years, that

star, Alpha device fragment

particle a critical mass

fission that we have

an americium such

along with the spent wires,

extraordinary rocket

to 70%, we can deliver

of 50% we can deliver

to earth. We assume

It is thus to mass

fields of 103 G direct

from the orbit

system probability

is 245Cm or 242Am.

an americium-powered

uses fragments

rocket fragments

supply expected

Centauri, start

from the operation

tons in 113 years.

concept carbon

escape structure

solar so that

a 10-GW reactor

system. the

A critical mass

up to the

by nearest

let us consider

PERFORMANCE

still maintaining

in a sufficiently

as the energy

is to minimize

For propulsion

4.1 light-years

in 148 years.

at a minimum

in 100 years,

in 121 years,

fifteen metric

fueled fission

are discarded

metric easy

To fission

a mechanical

of six metric

as propellant.

thirty metric

in 87 years,

is predicated

thirty metric

are trapped

If we could

in structural

the reactor.

the escape

of available

POTENTIAL

for optimal

periodically.

the transit

the fission

is currently

ten metric

the useful

possibilities

of payload

a mission

for about

40 years,

propulsion

thereafter.

fragments

a fission

the goal

operating

is worth

Magnetic

fragment

reactors.

reaction.

payload.

Success

increase

coasting

will not

illustrate

exhaust

on the

assume

a mass

to see

opened

fraction

escape

ejected

include

directly

out of

serves

supply

twenty

3-1 1

fission

return

would

wires,

Thus,

fibers

mass

while

high

tons

time

also

plus

size

The

and

that

fuel

For

the

for

star

that

times

would

rapidly,

system,

requires

is used.

sensitive

in reactor

to lengthen

ton payload

are required

if the payload

proportionately

time increases

small-somewhat

longer mission

the components

with a decrease

if it is found that

the mass is large.

the mission duration

in power would increase

except a significant

rocket holds the potential

below 10 GW is acceptable

below 5 GW, a power

is reduced but obviously,

3.0 High Energy Sources for Space

It should fragment moderator

power. a 20% reduction

is not overly For a 30-metric

a new technology, In addition,

at 10 GW impose too much mass. Of course,

fragment to the nearest sufficiently

be noted that none of rocket if

to a small and the trip the level the cooling the

of a less than 100-year mission and structure mass can be kept if

Fortunately, reduction structure time by only about 5%. As the power trip time begins somewhat requirements operating reactor in reactor power.

development 242”Am. interplanetary missions, uranium-fueled, funding could be flown by the end of the century. show an artist’s (Cha88)

rocket using 239pu as the fuel In Figure 3 {Fig. 3.3} we rocket. fission fragment

of rapid Such of course. or maybe even a

be much easier, could be done with a plutonium-fueled,

of the fission for the organic infrastructure

Indeed, we believe

large as deep

that with sufficient

amounts but

fission fragment

of a prototype

be required

to produce

a prototype

conception

missions,

stressing

rocket.

travel,

would

Less

such

3-12

3.0 HighEnergySourcesfor Space

Safety discussed high Earth orbit where design radioactive if attractive contaminants which has to be pursued since it will be necessary made available depth in Cha88-UCRL-99474

10% the fissile fuel might be used to light and reach (Cha88)

offer exhaust is another matter fuel production the capacity in further

remote space flight missions, this would the

to velocities 100 t of to 1/20 the speed of 100 years after

For a trip to Alpha Centauri, coast This for 75 years. needed for future missions.

payload masses For example, a 500 kg payload approximately

The specific impulse is quoted as exceeding 106 seconds.

interesting speed of accelerate Alpha Centauri

as well as the environmental to produce

energy would not be a concern.

contaminating and preliminary high for

missions, The fuel availability

utilizing this fact would allow acceleration

for 25 years and is

Fig.3.3. Fissionfragmentconcept.

the assumptions concept

it return to Earth.

fragments create the Earth.

the reactor would not be operated

the 15 GW reactor would operate

is not is in a That of

during to state that

the vehicle except

beyond is discussed

the fission obviously

the level of performance

operation until

would concerns

from commercial

the possibility

developmental

The concept

A propulsion

i.e., where

approaching

effects of

are valid,

additional

quantities

approach

analyses

reactors.

(Cha88).

particles

concept

scheme

exhibits

launch.

testing

would

which

light.

3-13

over

and

For

not

3.4

that

3.4.1

mass

fusion

(Table

energy

unsafe,

namely,

reacting

specific

produced

application,

propellants.

impediments

to advance

in harnessing

It is a reaction

BACKGROUND

(proton-antiproton)

to the experimental

are of monumental

reactions 3-1),

MATTER-ANTIMATTER

can by contact

release would indicate.

to serve as a fusion ignitor.

to be Major be as

theoretically the research

to the use of PP as a space energy

3.0 High EnergySourceslor Space

The total system performance may prove matter-antimatter

While there are very significant there is one intriguing source,

than the specific energy the matter-antimatter is inherently

conversion and the test demonstrations which remain to be performed state of

Although matter-antimatter provide the greatest requirements order magnitudes. less advantageous difficulty anticipated. hypergolic

Antimatter reactions by which Antiparticles this source of energy, would have to be manufactured, would annihilation required the reaction decrease

The reaction reaction charged significant percentage form of hard gamma substantial mass for heat conversion. and muons, 1,248 MeV energy. positron, producing

for particle by particle which any time soon, even if suitable mass of energy from this to

The concept proposed nuclear matter-antimatter energy particle E=mc 2, making possible levels.

back to 1953 when S_.nger The of high yielding system at high energy

and A in the using into neutrinos the pion’s

in nuclear is the only method experiments. for as a fuel

proven. to the energy extractable by some are projecting

and a unit mass of antimatter estimates

to obtain. from very high energy accelerators.

of using antimatter the use of antielectrons

the PP energy appears to thrust without

Each proton-antiproton relativistic

not be cost effective reactors

an electron, 0.5 MeV gammas.

The muon, and 2 neutrinos.

4.0, decays and electrons

(approximately rays which

as a product to energy,

reactions and electrons

275 MeV and 973 MeV of

is about 104 to 1. Current

It has only been observed

as reacting fuels (San53).

have not been observed

in the following manner.

physics where all of

produces pions.

1,876 MeV energy

Thus, antiprotons,

into high energy

a theoreticallyvery

in the form of

into a react,

to manufacture

The positrons

are observed

one third) of

as discussed

The charged

pion decays

pions decay

The neutral

is converted

is extremely

annihilations

light weight

to consider

are difficult

respectively

researchers

the matter

antiprotons

in Section

to convert

had been

The ratio

to obtain

to 100:1.

produced

produces

designed

naturally.

carrying

gamma

difficult

neutral

energy

dates

each

rays.

That

3-14

able

are

3.0 HighEnergySourcesfor Space

From a safety viewpoint, it should be noted that if any of the antimatter ever came into contact with matter, the results would be devastating. Working with it should prove to be quite interesting!

Very limited study has been accomplished to perform thrust conversion directly from the reaction and also as a heat exchanger for a working fluid. Magnetic nozzles are employed for thrust. Magnetic containers and system components will be required to store, control, and work the antimatter. The engine’s operation is described below.

field This rocket design concept uses a static magnetic configuration in the shape of a conical The rocket nozzle. magnetic field is produced by the turns of a coil that increase in radius and separation so that the magnetic field lines form straight lines, all of which emanate from a common center on the axis. Within the field is space vacuum except for the antiproton beam, the hydrogen beam, and the annihilation products.

The dynamics of the motion of the pion in the magnetic field confines the pion to the surface of the cone. If the pion velocity vector is to the right, the pion will spiral out of the engine to the right and produce thrust. If the pion velocity vector is to the left, it will spiral toward the vertex of the cone, circle around just below the tip, then reverse direction and spiral back out to the right and exit the nozzle. Only the small fraction of pions with a velocity vector nearly parallel to magnetic field line at its point of origin will be able to travel up the throat and out of the engine the wrong way.

The specific impulse of this engine is the velocity of the pions at their time of formation. For the mean kinetic energy of 250 MeV, this is a velocity of 94% the speed of light or a specific impulse of 28,800,000 s! The energy from the 30 A of antiproton ions will run this engine at the same power level as the three Space Shuttle Main Engines, 24 GW. With the high specific impulse, however,

The charged pions produced by the PP annihilation follow paths that are along a cone whose vertex is the common center point of the magnetic field lines and whose surface is defined by the initial velocity vector of the pion. The vertex angle of the cone depends upon the velocity, charge, and mass of the pion and the strength of the magnetic field at the point of tangency.

The beam of antiprotons enters from the left and collides at a right If the two angle with a beam of hydrogen coming from below. beams are 2 x IO20 ions/s each, then 95% of the antiproton ions are in each beam is approximately 30 A.

annihilated. 7.23

The ion current

3-15

0.9

ENGINE

Refer

thrust.

(For83)

70 N of

._--------:?

of the engine.

in an interstellar

as the last stage

to Fig. 3.4 for a description

… _.’_RA_Y_R _

3.0 High Energy Sources for Space

Such a design probe

this 24 GW of power only produces best suited is probably design.

all system aspects flight systems form of gamma specific

utilization That will decrease

Fig. 3.4. High exhaust velocity matter-antimatter

from a space is in the

the energy of

be taken into account.

propulsion system concept.

In any consideration

… -.c - -

… zoo,ooo Ill

o.4s.—o.—

”… . ”_’

power potential.

_o”’-:

is that 40% of

design rays.

of comparative

of this nature,

(For83, Fig. 7-9)

it is essential

The greatest

the effective

the design

perspective

g_,,$_,

evaluations

o.z_’

LINES ._ -_

realization

drawback

g=ur, r, 25,000

”. _

,’°”

FIFLD —_

:[Ije_’-

3-16

0,27

that

WIDTH

”

COIL5

,, .

”,..,.

.-,.

.,,,

”

“Z

will

this

has

and

one

why

only

very

time,

study

could

Flight

which

There

nearly

for a

thrust.

design

design

source

benefit

reason

feature

directly

system

energy.

mission

reaction

analysis

nowhere

comprise

attractive

conditions

how real

as fusion.

to impose

to convert

as a heat

for a flight

components

for a flight

light weight

as indicated

performance,

be required.

high energy

to determine

accomplished

of magnitude

as developed

and shielding

Heat balance

system using

is a particularly

The source

namely ease

for release

fluid. control,

should source,

nozzles the

working store,

can be expected

space, content,

by the two order

of matter-antimatter

research energy

and also to serve

energy increase

Clearly, “ultimate”

some from the

not been conducted.

to serve ignition,

this form of energy.

thrust exchanger

is as the this at

could antimatter,

in specific difficult

very has been

Magnetic and work

be employed magnetic

for producing containers

be performed it should but

fuel as conceptual

to examine be considered

that should make this concept

3.0 High Energy Sources lor Space

as an ignition and the

a technique in a dual mode

solutions is not as attractive

for application was matter-antimatter.

Borowski AIAA/SAE/ASME/ASEE

thrust low plasma to achieve.

(For83,1-17) and cooling antimatter

for remain. antihydrogen

is a big question man

examined: seconds more

high specific energy

low specific impulse.

configuration. will

in a stable magnetically

with annihilation

The high potentially

there from the

Propulsion 23rd

with matter-antimatter

efficiency protect

concepts Among

Methods that

issues levitated

impulse, The

is the production

by Dr. Borowski

at the fusion

One conclusion

system design

on that energy

energy favor

“On the basis

into propulsion

show promise

are underway,

to outperform

be significant

and material

Two different

is considered

of preliminary

and mission

thrust The

the concepts

of advanced

next century

least worthy

interplanetary

be retained

Ibf coupled

the plasma

the Aerojet

“expensive.”

by the Air

of must

Conference

the atoms

for difficult

operational

In another

latter will

considered

technology

conversion

for space

The ice

Propulsion

comparing

conducted

completed

propulsion

missions.”

presented

antimatter

“feasible,”

a survey

The first

Research

are also

analyses,

of study.

radiation.

in 1983

reviewed

shielding

STATUS

a paper

primarily

Inherent

Forward

systems

Forward

systems

trapping

reached

(Bor87).

requires

concern

(For83).

by Dr.

Institute

concept

engines

needed

energy.

specific

(Bor87)

activity,

gamma

Limited

studies

appear

difficult

~2,000

modes

source

be of

in the

Force.

critical

reveal

power

fusion

space

would

which

’.-106

travel

flight.

could

since

basic

quick

3.4.2

been

have

Joint

3-17

fuel.

high

cost

with

was

The

and

that

fuel

any

not

the

but

did

Dr.

for

state.

particle

quarks.

specific

physics.

nowhere

MATTER

possibility

as fusion.

conversion

are taken

is included

for a fight

system is

in a natural

understanding

of PP energy

3.5 STRANGE

Strange matter,

like antiparticles,

realize the higher

whether yield,

system design will

are being suggested

There will be significant

have not been observed

Strange There is a

a basis for a very compact

It is not the so this

3.0 High Energy Sources for Space

size. At the present

that when system considerations

it would provide time, only experiments

has only been through of equal numbers

high energy of up, down, and strange

stable if it can be grown source of

as nearly developed concerns with the development

and use of antimatter. into account, energy

that strange matter might become If so,

Their detection matter consists theoretical to a sufficient energy. the theory.

The analytical ostensibly cost and safety clear spacecraft concept was not pursued further.

Strange matter advanced quoted release will be in the form of gamma radiation which, as discussed as desirable

Work Washington. which This concept limited to near sun solar system exploration high energy mission

Dr. Forward’s propulsion sufficiently recommended metastable annihilation.

and to indicate where level would be high, the energy

of to a plasma fluid. is it the

for advanced 28 were that Four were solid

3.4, had evaluated flight. preliminary

for a reduced mass solar sail, perforated with holes

the solar energy is limited to a specific

for more detailed study in the second phase of

uses solar energy to heat an alkali metal

This is a concept smaller

as <938 MeV (energy/baryon).

and transfers impulse

sources might be headed.

64 concepts concluded

Section space for

solar sails, and antiproton

of ~1,500 applications

to a hydrogen working

than a wave length of

to illustrate the current

Solar heated plasmas:

solar heated plasmas,

for space applications

study technical

and will not meet

as purely charged

for defined

of Section 2.0.

energy well

the University

This concept

the contract:

requirements

The energy

solar sails:

percentage

has been

to validate

Perforated

perforated

performed

proposed

on solar

seconds.

analysis.

captures

(Sha89).

A large

plasmas

particles

Further,

OTHER

thinking

helium,

heated

energy

earlier,

report,

is not

light.

3-18

The

3.6

3.7

upon

SUMMARY

Based conclusion

research activities

Solid metastable helium:

3.0 HighEnergySourcesfor Space

This concept uses lasers to make excited helium stable and magnetic fields for forming it into a room-temperature ferromagnetic. The theoretical impulse is calculated to be ~3,500 seconds, probably ~2,000 seconds in an operational engine.

Whereas the solar energy systems have many advantages from environmental, that source of energy is and perhaps from some safety perspectives, It could inadequate for the far distant missions where the solar energy is low. be a very useful concept nearer the sun. Those concepts were suggested as new ideas without any developmental to back the performance of these systems. The payload mass delivery capability of those propulsion systems has not been addressed, which was not the study intent. Additional details and bibliography are available from the reference.

Space The other basic energy sources, solar, will continue are appropriately could established

a negligible chemical, and space sources. but to produce

effort was placed on further space

exists for a United States The program would implicitly

applications, energy those in performance,

data base and will be more difficult

the performance is that

in this study, of high energy

space defining missions.

to the mainline DOE program.

has received fission,

considerable energy

requirements is the most

of missions source

Opportunity research.

role in space fusion

to take a leadership

a safe, economical,

As a consequence,

too, an alternate

effort worldwide.

in accomplishing

Matter-antimatter

to have space

electrochemical,

being pursued

mass efficient

from a less

flight system.

confinement

the unique

theoretically

programs.

programs

approach

research,

however,

research

potential

provide,

namely,

the for

exceed

suffers

drawn

fusion

viable

future

3-19

and

for

4.0

the

4.1

this

ash

The

total

used

under

“ash.”

Some

fusion

and/or

to as

power.

energy

to the

contain

A brief

join to

referred

quantity

appears

a small

particles

selected

FUSION

products

although

nucleons

reactions

In fusion

equation,

principles

of mass

the right

nucleons,

reactions,

PRIMARY

the main

secondary

discussion

contributor

is usually

is burned

as kinetic

conversion

NUCLEAR

GENERAL

has been

to present

is provided

E = mc 2.

of charged

fundamental

light weight

form other

REACTIONS

DISCUSSION

the reaction.

to a specific

in the report.

loss between

high temperature

set of conditions,

and key parameters

depending controlled

for in designing

the initial in accordance

reacting mass with the

upon the fuels fusion

fusion determined rest mass

of energy and the residual

The by the mass the reaction

and to penetrate forces reactions fusion initiate with a few eV to initiate

average cm 2, and the relative

in achieving scheme

challenge confinement

product ion velocity

yield 4 x 108K.

10 keV in comparison

is large, chemical

requiring reactions.

indeed Sufficient

The To fuse

have be met,

fuse be met.

currently however,

now is that we

of nuclear

positive reached

simultaneously

a satisfactory

the mutually

as discussed

to overcome

rate fusion

and with a

high energy

be imparted

the quantity

of nucleons

in Fig. 4.1.

temperature

that a net

the proper

penetration.

two nuclei

of nature’s

in nucleon

a function

of energy

net power

is plotted

numerous.

sufficiently

of energy

respective

parameter

conditions

a fashion

controlled

nucleons,

reaction’s

statistical

to result

elements

(108-109

repulsive

Coulomb

(velocity)

neutrons

is <_v>

Whether

the (v),

colliding

reaction

in such

cm/sec.

number

interest

plasma

results.

occurs,

several

plasma

Hence,

greater

section

to the

energy

or not

is the

impact

below.

nuclei.

before

matter

kinetic

status

fusion

which

Other

cross

quite

point

must

here

than

their

fuse

is a

ions

The

rate

The

are

4-1

(c),

°K)

will

“_7

“16

13_

t- O

O (3) (/)

D-T

(3.) rr

c’3 E (J

10-16

V $ (D E

/ / /

4.0 General Discussion of Fusion Reactions

… / i o,°.7/,,o,”

Neutrons, a transfer without ions, are slowed heat the plasma time and fuel density and > 2 x 1015 cm-3-s heating radiation

without and the burn can proceed systems. auxiliary The heating in the form of neutrons from the plasma for space is shown

The product determines ion temperatures, high ion density plasma the plasma density

distribution for the three main fusion fuel cycles of

and their energy of large (> 5x1014 the charged

of energy by the background and any cold fuel

Reaction parameters and cross sections for various fusion reactions (MU76).

from the plasma i.e., to

occurs, further approximate and radiation

cm-3-s for D-T fusion convection,

input. When the product is sufficiently

products, then serves fuel confinement

figure criteria), where time (s).

density. must be confined

in addition to being driven to high

energy and synchrotron

and _:is the energy confinement

of merit of a n is

the plasma input

ION TEMPERATURE (keV)

time (_) at a sufficiently

is said to be ignited

is usually measured

product and

as bremsstrahlung

by the parameter

from conduction,

for an adequate

The confinement

are immediately

to the plasma.

lost fusion

from external

this condition

for example),

The charged

can balance

the reaction

The plasma,

(n_: product)

n_ (Lawson

for D-3He,

the energy

of energy

(ions/cm3),

to sustain

as typical

of energy

coefficient

products,

radiation.

10-le

Fig. 4.1.

burning.

reaction

interest

plasma

energy

losses

When

with

rate

lost

per

4-2

the

(n)

100

D-T

D.3He

Thermal

energy

particle

compared

San88)and

Neutron power

Catalyzed D-D

Fig. 4.2. Approximate

with the charged

4.0 General Discussion of Fusion Reactions

_ Power available for direct thrust radiation []

in Fig. 4.2 (Men89, available.

to do direct and neutrons must be converted cycle and used to drive an ion or plasma neutron heat must be

field. primarily configuration is a plasma energy density

the heat may be The goal capability. to keep the radiator mass as low

For magnetically roughly pressure, ion temperature, and, cycte Section

Let us now pursue Only useful work. thrust. to electricity thruster,

of Analyses can ignite and sustain achieve amount

since they can determine From an efficiency in the smallest

the reaction one would like to The actual to and,

disposal extracted would be to maintain

the maximum fuel burn-up of

to space by the spacecraft’s are an impediment

of ignition on the reactor

and B is the magnitude Ti, and n_: for

can be made available for efficient is available

scales field value of fuel in

distribution of energy among charged particles available for direct

energy particle from radiation

of energy wastes for a small on-board

to a lesser 8.0. The parameter,

as (132x B4), where 13is the ratio of plasma

how these the charged the energy

give an indication, reaction.

Hence, high performance

viewpoint, space possible.

radiation which appears as surface heat.

the magnetic depends

density to magnetic

thrust, neutrons, and thermal

thermal propulsion

as in fission electric

losses are essential

radiated neutrons

by a less efficient

power mainframe

upon the reactor

systems. Waste

a radiator mass.

sources power

5% to 30% of

to the required

on the chosen

The particular

To be useful,

as discussed

approximately

is consumed

fuel burned

as possible.

applications,

13, however,

the highest

temperature

the fusion

is strongly

dependent

parameter

for space

properties

Some of

radiators.

electrical

the fuel

pressure

confined

devices,

burning.

requires

whether

design,

extent,

in the

power

fusion

since

4-3

fusion

design

earlier,

closely

concepts.

light element

considerations;

Primary Reactions”

reactions which

and the reactor’s

tied to engineering

more capability

there are numerous

Proton-Based Fusion Fuels

Deuteron-Based Fusion Fuels

T + 4He + 2.561 MeV (2.561 MeV)

(Mil76 & McN82), Table 4-1a.

As mentioned can occur

TABLE 4-1a. Fusion Reactions (McN82)

4.0 General Discussion of Fusion Reactions

varies widely among plasma confinement

Primary Reactions p + 6Li _3He + 4He + 4.022 MeV (4.022 MeV) p + 9Be ---,-4He + eLi + 2.125 MeV (2.125 MeV) p + 9Be ----D + 24He + 0.652 MeV (0.652 MeV) p + 11B—,—34He + 8.664 MeV (8.664 MeV)

D + T _ n + 4He + 17.586 MeV (3.517 MeV) D + D----p + T + 4.032 MeV (4.032 MeV) D + D----n + 3He + 3.267 MeV (0.817 MeV) D + 3He-,.-p + 4He + 18.341 MeV (18.341 MeV) D + eLi -,.-24He + 22.374 (22.374 MeV) D + 6Li —,—p + 7Li + 5.026 MeV (5.026 MeV) D + 6Li _ n + 7Be + 3.380 MeV (0.473 MeV) D + %i _p D + 6Li ---n + 3He + 4He + 1.796 MeV (~1.134 MeV)

Secondary_ Reactions 3He + %i ----p + 24He + 16.880 MeV (16.880 MeV) =He + 6Li --- D + 7Be + 0.113 MeV (0.113 MeV) 3He + 3He -----2p + 4He + 12.861 MeV (12.861 MeV) 4He + 9Be ----n + 12C+ 5.702 MeV (0.439 MeV) 4He + 9Be --- n + 34He - 1.573 MeV (-) 4He + I_B_ p + 14C+ 0.784 MeV (0.784 MeV) “He + _B --- n + _4N+ 0.158 MeV (0.011 MeV) p + _°B---4He + 7Be + 1.147 MeV (1.147 MeV)

Secondary_ Reactions p + T _ n + 3He - 0.765 MeV (-) T + T--- 2n +4He + 11.327 MeV (~1.259 MeV) T + 3He--- n + p + 4He + 12.092 MeV (~6.718 MeV) T + 3He-,.- D + 4He + 14.319 MeV (14.319 MeV). 3He + 3He —,- 2p + 4He + 12.861 MeV (12.861 MeV)

Fig. 4.1a. aEnergy release is Q(Q+), where Q is total energy release including the energy of

energy only (p = protium, D = deuterium, T —

Table 4-1b, during the discussions

the neutron and Q+ is the charged-particle

We shall be concerned

fusion fuel applications.

primarily with just

on space energy

tritium, n— neutron).

reactions,

listed in

those

three

i.e.,

4-4

11B

(~50%)

D + T

important

D + D
D+3He

reference)

T + 3He

A. The most

=e ++D+1.42Mev

for Space Applications

— 3 4He (8.7 MeV total)

B. Aneutronic Reactions

= p (3.0 MeV) + T (3.67 MeV)

C. Potential side reactions (for

= D (9.5 MeV) + 4He (4.8 MeV)

p+ 5.3He + 3He

= n (2.45 MeV) + 3He (0.82 MeV)

= p (14.68 MeV) + 4He (3.67 MeV)

— n (14.07 MeV) + 4He (3.52 MeV)

tusion reactions for space applications

= 2p (5.7 MeV each) + 4He (1.4 MeV)

4.0 General Discussion of Fusion Reactions

= p (5.4 MeV) + 4He (1.3 MeV) + n (5.4 MeV)

TABLE 4-1b. Fusion Reactions for Consideration

temperature important, become fuels would be predicated reaction to bremsstrahlung

i.e., a proton and alpha reaction while still from the least

reaction particle. having sufficient statistical

losses these the losses due breakeven,

95% neutron free under free if some advanced

i.e., source and are therefore

products As shown by equation

is nearly an aneutronic The source

of p_11B is 300 MeV, a level where bremsstrahlung

and 3He-3He that of

= p (10.1 MeV) + 4He (0.4 MeV) + n (1.6 MeV) (4%)

however, is that 3He is not

to ignite on Earth and will

because of neutrons, reaction.

not suitable for space energy generation.

is more difficult readily available

the two charged it

need to be driven with a perfectly

with in the table for

p-liB aneutronic, is a trace

of these ions is only marginally

noteworthy the production

of the primary fuels or of their

Another require lunar

of D-D. The D-3He reaction

— 2n (10.03 MeV) + 4He (1.3 MeV)

The D-3He consideration

It can be over 99% neutron

and as a result are not

not since they

reactor configurations

is, occurring without

study and research.

reaction Additional

(1) to ignite.

Use of However,

has its advantages

selected. comprise

prove to be sound.

and also increased

and disadvantages.

radiation energy

are although

Each reaction

by higher atomic

likely to achieve

fuel combination

has the major

upon extensive

the remainder

purely there

side reactions

the elements,

side reaction

the reactivity

of producing

in the p-liB

The ignition

as either of

is calculated

The D-3He

they would

of neutrons

that were

are shown

than D-T.

percentage

unintended

radioactive

associated

conditions.

advantage

sustained

reference

is a low

to be at

products.

reactions

particles,

reactivity

radiation

reaction,

number.

a large

external

reaction

efficient

present

is low,

against

section

T + T

energy

results

typical

cross

there

(55%)

(41%)

they

The

i.e.,

For

4-5

are

its

that

(DOE)

Center

energy

studied

reactor,

(Wit86).

sources

80% of

complete

alternative

(WCSAR).

(Anom88).

of Energy

extensively

To provide

it produces

Department

surrounding

in a blanket

the released

the tokamak,

and Robotics

3He workshop

is not attractive

in 1991 showed

held at Cleveland,

Lunar 3He mining

(equation neutron

production.

been Automation

fuel cycle is the easiest

D-D (cat-D) are assumed

The mainline designed

the University Studies

the D-T plasma the advanced

of using tritium are its radioactivity

for Space and practicality.

4.0 General Discussion of Fusion Reactions

of Wisconsin indicate feasibility

terrestrial to burn D-T. That

reactions with 6Li The Aries HI study early

in a dedicated Fusion Power Workshop”

is to ignite, and the fuels are

available relatively (12.3 year half-life) neutrons. energetic

in from sea water, and tritium is

fuel cycle has been suggested to be recovered

Lunar mining operations “The NASA has

mining or other expensive were discussed Lunar Helium-3

made from neutron in the blanket. tokamak will not burn D-3He.

Drawbacks on Earth. and the fact that Deuterium is readily extracted

The basic D-D reaction and a significant density D-D, a “catalyzed” reaction products until densities energy demonstration

Ideally for space, totally devoid of neutrons. conversions from neutrons potential inefficient surrounding bombardment penetration the wall material accounted which for many

i.e., one thrust and power and since the freedom have particles of heat, an the of This That deep causing system aspect will be program due to lack of access;

due to a low fusion power for in which the D-D into the plasma power its of for

is desired since efficient direct from charged energetic, in space

and “D-3He clearly offers the best combination

radioactive in deep first wall penetration

That are made possible eliminates

lose its strength. This reactors by a maintenance

candidates applications” low neutron (Mil87)

… some fusion systems per

is achieved. to that of D-3He, but

The Air Force Studies conclusion

the first wall’s atoms from their normal position

to ultimately for on the terrestrial

the conversions for

can reach a large fraction

for and that yields

and reinjected reaction

product by neutrons.

results will displace

powers that make

for energy design

the National Research

only by the generation

and relatively modest

space stimulates

potentially power

(kilowatts them

will not be available

space applications

first wall structure

like to achieve

it still produces

is a theorized

ionic product,

characteristics

cycle which

bombardment

offer specific

and logistics

at this time.

consumption

confinement

comparable

one would

generation.

conditions.

propulsion

and total

damaging

additional

neutrons.

kilogram)

a purely

particles,

reached

Neutron

solution

a plan

Council

energy

power

Board

space

which

flight.

lacks

That

both

This

that

4-6

the

for

life

will

not

the

4.2

are

fuel

will,

The

time

duty

and,

does

man,

three

either

which

cycle.

totally

fusion

cycles

and/or

D-3He

always

require

In the

without

interest

neutron

OTHER

reaction

oriented

greatest

FUSION

including

shielding

eliminate

the first

reactions

neutrons,

operating

reactivity.

therefore,

of being

reactions,

of choice

remainder

Any D-T

in space

This and

are likely

separation

to remain

a reactor

Secondary

expensive.

radioactive

NUCLEAR

than with

two other

accessible,

of massive

replacement

the neutron

maintenance

REACTIONS

due to their

system will

recommended

the reactions

be a function

comprehensive

the installation

a new hazard.

towards 7.0.

in this discussion

and sources.

difficult, exposed

problem. reactions

design In spite

solutions the of

flux and the mission

rather problems

equipment, but

from the this

hazardous, material

of neutron radioactive

categories

or power

this time.

equivalent

commonly

generated

as 1958.

catalyzed

to attach

reactions

a charge

attractive,

to make

catalyzed

produced

hydrogen

formation

neutrinos

to occur

but with

reactions

attractive

reactions

to Bohr

sufficient

limitation

although

enhance

nucleon,

attaches

valuable

practical

a mass

(Jon86).

appears

(Raf87).

reaction

pertains

half-life.

system.

another

allowed

actually

protons

a very

provide

second

half-life

panicle

causes

decays

ignition

to the

output,

energy

forces.

Muons

carries

should

occurs

atomic

D-3He

period

during

option

atoms

radius

fusion

space

fusion

Muon

about

Muon

these

since

liquid

<_v>

been

short

gain,

have

time.

rate,

high

time

This

plus

cold

The

that

due

has

fuel

flux

this

are

4-7

not

the

but

the

but

ion

for

is,

i.e.,

than

where

by all

seems

greater

Studies

interest,

released

reactivity

polarized

is aimed

approach

nucleons,

to fusion.

spin of

the D-3He

in achieving

the amount

to efficiently

the plasma,

are essential

at establishing

is substantially

is the potential

to be increased

a self sustaining

reaction too,

efficient methods

has a very positive

part coherently

fuel nuclei and for bringing

involves are a function

for D-T and D-3He is calculated

Nuclear to the reaction.

This, of course, are being

the muon power by

4.0 General Discussion of Fusion Reactions

as D-T. Of great neutrons.

to have the same to depress

reactions. the nucleon spin just prior

reactions which The ultimate success of an efficient

muons catalyzed balance. the development

of this form of cold fusion may be determined light weight accelerator.

reaction The by 50% using spin the D-D benefit on produce

Another cross sections plasma polarized dependence reaction, reducing polarized

and hence, system mass. performed fuels that would provide an overall net benefit

The atomics producing inside sufficiently sufficiently conclusion sufficiently same time the necessity was stressed under

consideration This fusion concept Laboratory. Dr. Kulsrud 1982. During the meeting in Italy in which muon catalysis discussed, was that

Of all benefits the possible the most attractive would make a nearly neutron physics is not able at possible. of this question.

and wall so as to insure the depolarization that than the particle fusion time (see e.g.

for them be time is The [2]). can be used, the test

reached that polarization If it does become a reality for the terrestrial

weak longer was reached that, long depolarization

thought was to effect a reduction of 2 reduction

from spin-polarizing be the suppression

the fusion plasma the neutrons of

of D-D reactions is achievable,

The initial appears controversy

this time to tell us definitely whether

by in were (Ku187)

The conclusion this time. on at

and polarization fuel paper

It is hoped that new experiments

be counted system

in the Kulsrud advanced

cannot application,

if appropriate materials

of a direct experimental

times may be hoped

lead to a resolution

here is quite clear

only remains.

fusion conditions.

and investigation

by 100; now it

It was proposed

It is unfortunate

the conclusion

effects must

the Princeton

has received

free reactor.

that nuclear

significant

collisions

a factor

although

reached

(Peg87)

Physics

Plasma

this is

some

that

for.

4-8

will

4.3

SUMMARY

4.0 GeneralDiscussionof FusionReactions

studies would be required to examine the net benefit to space applications. Recirculation power requirements will be a topic of great interest to the space program if spin polarization is proven beneficial.

For space flight applications where mass is always at a premium, the most efficient systems are those permitting the minimal system mass. For fusion the theoretical physics has been well established, the difficulty being in the physical attainment of extremely challenging physical parameters. Of the various nuclear fuels possible, the space application benefits greater than the ground program from reactions that maximize the production of charged particles and minimize neutrons. The optimal fuel is, therefore, considered to be deuterium and helium-3.

4-9

_i_i _

will

5.0

FOR

small

levels,

levels.

In fact,

SPACE

suitable

capable

systems

only by

ENERGY

exceeded

are large

for yield

determined

high thrust

and power

conventional

(3) variable

with respect

CAPABILITY

high specific

OF FUSION

characteristics.

CONVERSION

THEORETICAL

(2) moderately

matter-antimatter

PERFORMANCE

of generally

(1) very high specific

category considered

and greater currently

to space energy applications:

performance characteristics

systems Fusion energy

are theoretically they

energy only, as envisioned

energy and high power density, annihilation,

at high energy the megawatt not are the more where

Fusion propulsion operation devices and applications economical performance

of continuous producing presently, energy better, more has five key desirable

impulse practical specific for space. could yield a specific Toroid provide could could be suppressed Confinement Fusion been analysis be beneficial.

power 10.5 kW/kg; that by using polarized D-3He fuel. A conceptual (ICF)

of MCF values end by the low plasma can be currently

in the thrusting mode, limited of approximately

parameters design Compact neutrons Inertial has

While operating reactors mass

are mandatory interplanetary power capability

characteristics and interstellar of

at a 20 GW power potential

fusion (> 1 kW/kg) shows

leads to attractive Torus

the D-3He fusion high specific

detailed for space would

of 5.75 kW/kg, while a Spheromak

to be used for high

it burns D-T. capabilities

(1) High specific Dower:

is 3.52x1014 variable

The specific shown

(4) high levels of efficient

1015 ions per cc that

of much more energy

by the fusion product

system of producing

the maximum thrust

to produce the fuel.

up to the limit as

on the high thrust

power production,

reaction and

that a Spherical

in a magnetically

impulses which

than is required

By the addition

The potentially

(2) Moderately

One estimate

are ultimately

fusion (MCF)

space travel.

for propulsion

to determine

(5) creation

100 kW/kg

high thrust:

can range

in Section

maintained

for 2.0,

Tokamak

designed

assumed

electrical

confined

systems

designs

reactor.

energy,

specific

(Bor87)

specific

density

energy

power

level;

J/kg.

both

high

and

5-1

[3.

the

are

and

flight

offers

thrust

power

where

higher

shows

design

specific

needed

impulse

impulse.

the fusion

in specific

of a linear

advantages.

is beneficial

of Wisconsin

Dr. Santarius

The capability

to the plasma,

in Section 2.0.

of attention

for space applications.

from many researchers.

advantages thrust

In a recent reactor,

reactor can yield higher

favored performance

flow rate but at a decrease

field pressure, applications

density, a given of

for mission mass optimization.

5.0 Theoretical Performance Capability

by the scheme, [3 defined

tandem mirror the thrust

to the magnetic for space

The plasma characteristics proportional

determined confinement the quantity,

power for to the square

plasma pressure are inherently offer mission

reactor’s is approximately as the ratio of

and thus high beta designs high power densities

from That to vary the For as

of propellants the higher mass characteristic specific aeronautical discussed

fusion plasma energy to thrust using the D-3He fuel cycle has report on the results the

Conversion received of an analysis University being attainable (San88). per unit power system mass is 1.2 kW/kg. thrust (113 m) and massive fusion scaled schematic

size is 2000 MW, and the jet power level would produce system is long of the physics to Fig. 7.7 for a

levels on the order of 0.1 to 40 kN. The propulsion earlier, Refer

The confinement important becomes confinement research for its use.

As in all propulsion between shown for a typical terms of specific

space materials development concepts achievement, efficient

increase, efficient less time under high thrust

Higher mass fusion than configurations containment

is smaller in MCF plasma An economical

reactor may be designed for mass

subject which the space program will have to undertake

Upon the (ICF) That and higher

commercial inertial confinement

(payload mass to the initial vehicle mass) designs

A large from the the magnet’s

is maintained the fuel with

trade in Fig. 5.1 (San88)

and, times. Confinement

(1250 MT). scales of

impulse versus the ratio of thrust-to-weight.

n’c, during which As the thrust

required total mass for

driver to provide requires

to mass ratio of 3x10 -4 to 3x10 -2

large magnets load carrying

(Eng62). system design

using stronger insensitive

towards this propulsion

are expected however,

technology, an alternative

large sizes. engine.

parameter. less

and thrust propulsion

the advent of small,

for a given power

impulse fusion

since the amount

This performance

level operation

As mentioned

load carrying

is a trade-off

the reactor’s

are possible

That power

The reactor

not suitable

the plasma

confinement

of efficient

light-weight

lightweight,

decreasing

concepts.

therefore,

utilization

structure.

to obtain

complete

systems,

concept.

required

and for

vehicles

part of

drawing

burn-up

specific

fraction

drivers.

energy

power.

results

levels

is an

other

there

time,

level

is in

is a

fuel

5-2

for

’

‘""I

Q. O9

E_ O.. E

10 2 -

10 3 -

lo0

MASS-

104-

105-

THERMAL EXHAUST _

FUEL PLASMA EXHAUST

5.0 Theoretical Performance Capability

Fig. 5.1. Specific impulse versus thrust

are moderately at higher

given mission thrust

to tailor The missions

and specific in Section

missions to minimize

as specific optimal

of specific either

low thrust levels

considered produce

so as to accommodate

the propellant

specific specifically

propulsion vehicles

a thrust discussed

in which total the

optimizes with

impulse 2.0 are

and thrust-to-weight

They impulse

the in order

design program

are the averaged

can be attained.

those missions.

to the contrary.

given mission.

fast, manned

system mass

by a uniform

range allows

to accomplish

to be similar

and mission

as the flight

the mission,

requirements.

in somewhat

The means

augmentation

of permitting

low specific

acceleration,

Mo high

to maintain

that utilize

be tailored

2.0 to fly

in Section

a constant

operational

progresses

decreasing

are likely

to Weight

This and

propulsion

increasing

variations.

in design

variations

to weight

can and

approach

efficiency

important

fractions.

unlimited

(Moe72).

impulses

but will

missions

(San88).

powered

planners

flexibility

systems

different

inherent

payload

impulse

operate

Greater

mission

specific

effluent

to any

in any

feature

reactor

energy

modes

Fusion

aspect

values

shown

values

unless

mixing

Thrust

stated

meets

fusion

thrust

cargo

thrust

those

Ratio

while

thus,

used

1 0.2

early

10 -4

1 0 -3

1 0.5

over

1 0 1

The

and

into

5-3

the

for

is,

''''“I

'''“I

’

Ill

but

the

and

The

high

over

that,

Very

work

thirty

were

effort

Refer

made

thrust

Lewis

space

NASA

Center

energy

among

funded

activity,

specific

reasons

impulse:

primarily

research

(Mas59).

impulses

including

available

attractive

operation

Research

possibility

Research,

the main

on fusion

for space

continuous

Nucleonics

the most

A (Sch91).

the D-3He

significantly,

of Scientific

to Appendix

contributions.

years was

independently

High s.aecific

from plasmas

ago, begun

at Aerojet-General

(3) Extremely

a small by NASA

the Air Force Office

of continuous

application This

5.0 TheoreticalPerformanceCapability

plasma exhaust is, therefore, a key ingredient in the development of fusion propulsion to implement this capability. Variable thrust modes, along with specific impulse, are discussed under the specific impulse subsection which follows. The generation of thrust and throttling capabilities, at highly efficient specific impulse values, are very key, specific space research activities which a terrestrial fusion energy program will not pursue.

(Eng62). low acceleration

having to be ultimately

by Dr. Oberth mission

to a specific propulsion

for expected (NEP).

a propulsion produced

system by a nuclear

characteristics mission

of selected considered

of in 1929

chemical is given

(Fig. 5.2, San88).

set of calculations

options at

power system

for comparative

A comparison

gains of

be designed

levels, was

and thermal

performance

as allowing

In addition,

cycle was

applications

in payload

to perform

augmented

operational

recognized

in Section

substantial

a number

propulsion

a vehicle

in terms

important

purposes

a similar

designed

identified

separate

duration.

exhaust,

impulse:

systems

(diluent)

and at

as one

to vary

specific

fraction

plasma

electric

reactor

earlier,

benefit

modes

it was

thrust,

fusion

Three

thrust

direct

Much

mass

even

with

and

2.0.

and

fuel

5-4

the

will

I!li!_

ted

MASS-

Fuel

Plasma

Exhaust

Thermal

A ugmen

Capability

Performance

5.0 Theoretical

[] []

The plasma will products will have energies shown in Fig. 5.2, a reduced some impulses varies as the square

reactor fusion reactor the nozzle end allows high specific impulse

region of a fusion while In the Tandem Mirror

directly, the high temperature the temperature.

the reactor’s mass flow rate, and therefore

is approximately the plasma

10 keV to 100 keV (1 keV=107K),

temperature from about

plasma of root of

at yielding plasma.

The value seconds.

in the power-producing

OFF

for Because

rocket performance

the direct mode

the key equations

up to 14.7 MeV.

ions/cc), is low.

ready reference

low ion density

(1015

For below:

the relatively

are provided

high energy

as a result

electrostatic

system (San88).

the reactor

to escape

potential

Performance

for a linear

Specific

impulse

specific

operational

propulsion

Fig. 5.2.

range

thrust

level,

modes

very

fusion

5-5

rhv

the

with

flow

rhg

Isp=

which

plasma

= _(mv)

F _ Ve

particles,

boundary

the core

operational

to produce

temperatures

the plasma’s

from degradation

due to interactions

increases layer,”

P(W) = I/2rhv_2 = gFlsp

thrust by the larger mass

is added to the exhausting

are injected i.e.,

confinement by magnetic

5.0 Theoretical Performance Capability

thrust a low field strength magnet

impulse, but “scrape-off

into the plasma the mass augmented

the reactor and gasses thrust and specific This cools the plasma In the reactor’s

For producing end of mid-range mode. rate. protects neutral energy keV. In magnetic first wall material direct thrust. injection through range of values refers “Diluent” the two nuclear between

low range from about 1 eV to 1 from the to provide the direct plasma the cooler can be selected within a wide (Englert). seconds to distinguish fluid.

of specific the variation plasma the outside impact on the plasma the exhausted, plasma will of propellants

the low end range of specific by using are or as heat the

In the high thrust, impulse the fusion heated exchangers thermal properties

the energy produced levels (>100 MW) and to gain strongly reactors will be well within the realm of

Refer impulse. core) power energy become (thermalization) very

there will be only a small if requirements

stringent. with the fusion plasma is an undeveloped

To compare with fission, high power Multigigwatt

down into the 100’s of seconds flowing

from about 5,000 seconds to the inert propellant

operating mode through and exhausting

in a chemical propulsion to about 1200K.

the core plasma for

the reactor’s into the plasma

for a description layer

As with those are limited

as in the NERVA type propulsion

by economy fusion reactors.

the scrape-off directly,

energy and expelled

system. temperatures

is exhausted balance;

development temperature

fuels and a non nuclear

technology, Research

propulsion mode’s

by fusion is predicted

to Fig. 5.1 (San88)

it may be possible

of scale. Some

can be designed

can be extended

a heat-exchanger

to have reactors

as small as 10

impulse mode,

these plasmas

the remaining

in this report

understanding

good mixing

are insulated

but a and

fields which

to 1,000,000

are needed

(low energy

of a diluent

low specific

by material

confinement

a magnetic

the diluent

is partially

By varying

propulsion.

of mixing

to assure

and high

If part of

thermally.

estimates

however,

impulses

systems,

to be at

systems

reacting

use of

plasma.

indicate

specific

nozzle,

regime

Gases

critical

fusion

(inert)

mass

over

core

The

one

that

5-6

the

for

Its

for

the

this

and

The

with

less

0.03

offer

work

(800-

order

study

levels

upper

fusion

power

above

option

kW/kg

output

fission

is on

Others

kW/kg.

of 0.5

reactor

electric

Fission

nuclear

thermal

specific

Dower:

indicate

capable

requires

seconds

effective

whereas

consider

although

research

Isp limit

to 0.067

a space

too low.

at power

delivering

Increased

generated

a specific

increasing

propulsion

developed

100 MW.

the value

for space

achievable

projections

and large

considered

application.

in the SP

is ~10,000

kW power

perspective.

10.0 kW/kg

considerable

inefficiencies

requirements

and electric

an attractive

is considered

to the future

is designated

(4) High

MW (Rot89),

from an Isp

900 seconds)

but render

the conversion

reactor

now is on the

A system using

of 100 kW with

from a systems

approach. to

this is a topic which

limit of several megawatts

The NASA a 100

an Isp up to 106 seconds

the SP-100 reactor

standpoint inert mass

experimentation. being energy

5.0 Theoretical Performance Capability

in the field would for space

(103 to 104 seconds), may

in the form of microwaves, direct

diverted conducting electrostatically

from the plasma conversion

by the use of fusion

the amount thrust.

(Pos69, converting

of energy Power

power will be much

achieving designs.

capability high

Compare 5.3.

missions. less

can be anticipated

are high megavolt

energy, (Log86).

thereby vehicle

produce plates

use for powering

to be performed

are the subject

plate energy

Bar83). their

by a negatively

to use fusion

into electricity

to the ability

is to directly

For example,

of a part of

the electrical

of converting

system can

to electricity,

to the flight

for electrical

from fusion

high current

in improved

to hundreds

requirements

the “waste”

maintenance

(Fig. 7.17).

investigated.

electrostatic

to analyze

a relatively

synchrotron

in charged

to convert

efficiencies

low mass

and uses

conversion

be added

A system

spacecraft

a portion

to output

will have

producing

rectennas

of amps)

is based

Electrons

Typically,

electricity

reactions

on-board

electrical

systems.

electrical

(rejected

intercept

reflected

radiation

powered

methods

reactor’s

resulting

selected

particles

systems

whether

Another

voltage,

Various

needed

Section

specific

in Fig.

convert

interest

provide

voltage

plasma

relative

directly

system

aboard

vehicle

energy

power)

having

biased

similar

kinetic

thrust,

These

during

option

needs

option

power

fusion

space

future

levels

slows

study

flight.

trade

been

upon

been

(tens

have

heat

than

grid.

ions

The

that

2.0.

into

can

into

5-7

the

for

1 -

11,%

I 1O0

_/urrent

Fig. 5.3.

Ct conversion

required conversion

to convert to electricity

5.0 Theoretical Performance Capability

rejected-to-output power ratio. (Fig. 1.4, Mil76).

Reduction of waste heat with increasing efficiency. Here 1-‘rib1 represents the

neutron results level. Direct conversion

The mass thermal 40% efficiency The single 48%. Efficiency to 70% are predicted to realize subject

energy in a design has been researched produced by the addition of stages.

outposts will be the choice of a dual level the reactor at a energy

An important function can be reduced for lower plasma density at

…The straightforward. power efficiencies components.

consideration for scientific In this proposed

no detailed This is a new consideration.

value will be difficult 60%) will

system configuration production

not above to obtain …

between in total mass and

system has been reached.

complexity, been accomplished.

More experiments conversion.

a net efficiency Efficiencies

are essential paper on this

One area for electrons

options may allow switching

the current ultra Thus

design with this objective

design is increased

also for direct conversion.

the need for an alternate

and testing A recent

efficiencies percent

is to devise methods

or 49% high the

Some propulsion

the propulsion mode,

having approximately

and the a

to thermal energy,

perfect mating of

the high efficiency

once the mission

is increase

of of 60%

in mind has yet

require almost

system power

the efficiency

and negating

at Livermore.

at a modest

high Every

and power

states that

low power

the fusion

destination

to collect

increasing

operation,

operating

in Bar83

of direct

although

concept,

(Mor73).

reported

reactor.

thereby

(Per88)

penalty

(above

simple

fusion

stage

plant

path

all

5.1

solar

reduced

amounts

planetary

reactions,

resources.

(4 orders

production:

of energy

SUMMARY

from other

Fuels which

in comparison

system exist,

power sources

a small amount

large to create

the gas giant planets

(5) pQsitive energy

produce net power gains,

in contrast with matter-antimatter

problems power, higher

radioactivity of higher specific

5.0 TheoreticalPerformanceCapability

where must be expended

to the advanced that fuel, and making them available

Fusion, with vastly plus its characteristics electrical conversion for space missions. presently antimatter

reduced. in particular, are to be applied not be a planet Earth monopolized resources

of of energy as a power plants or other in fusion fuel sources and their space missions is, we must be capable local

Fusion reactions annihilation magnitude) space fuel. Thus, with fusion the burden on terrestrial space In addition, is greatly the outer satellites. should of using those fuel

with fission, thrust, and more efficient source release systems with matter- for the two order of magnitude

That advantage may not be usable when the system mass penalties which will ensue once the

increase one takes entire set of system requirements

system, warrants It is the most attractive

attention form of high energy

since it a less desirable

cost and safety alternative

have been determined.

known render

as an energy

into account

implications

in specific

significant

gained.

energy

5-9

6.0

later

AND

great

gains

unless

Hence,

FLIGHT

rejection

expected

SYSTEM

simplicity,

technology

mandatory.

economics,

reason for

performance

the functional

factors must

be addressed

are paramount

has advanced,

and practicality

the importance

the performance

REQUIREMENTS

CONSIDERATIONS

An overly complex

and flight operational

could be accomplished

evaluation anticipated

in its ultimate capabilities

is absolutely of

system from an operational

of a fusion engine is sufficiently

for use of any perspective

as discused was developed

in this report, in the course of

Operational space flight system.

the NERVA during the applications for

attributes system design initiation.

more simply and less costly and flight flight that at

is not Operational the 1960’s. considered. using chemical operational vehicle concept

likely to be accepted complexity was a major Another was inadequate The missions propulsion.

such that this study. to the degree that one can make judgments the performance

Fusion confidence This confidence must be tempered on a preliminary that is ultimately meet power system into the flight vehicle.

Thus, Section times), will be placed use. successful and the desired elements space reactor with the flight vehicle system.

power essential fusion those system and to make judgments requirements.

optimal minimal considerations indicate fashion, will provide the most effective

identifies the purpose the space reactor and the interfaces

along with the requirements Applications,” to define those

Before examining the important which

the key system parameters of

confinement system aspects are expected

We have seen in Section We examined

requirements from the space systems

assure the system in a timely towards

of and from the capability

is of a flight the fusion those

from fusion in Section that we obtain

high energy 4 and the extraction

of of that performance

level propulsion/electrical

reactor this section For

level which perspective

in and burn ultimately

a successful, predevelopmental

time to pursue program

derived (such additional

technology, if accomplished

Therefore, value trends.

program can reap enormous

2.0, is important

of difficulty with meeting

2.0 a range of missions

two flight of the

program management

high energy mission

For predevelopmental

the system design

achieving planned,

for the integration

or developmental

from projections

levels. of

this discussion

on the degree

the nature of

are separately

upon a fusion

from mission

considerations

and thereby

The earliest

requirements

a grasp of

considered,

of a fusion

the status,

as reactor

conceptual

in Section

constitutes

challenges

endeavors

dividends.

capability.

concepts,

approach

reactions

requiring

research

powered

“Mission

namely,

system,

reliable

impact.

A well

which,

phase

power

fusion

safe,

6-1

the

for

its

for

6.1

the

For

The

that

time

flight

6.1.1

value

mass

value

those

fusion

space

based

power

plants.

unique

energy

SPACE

beyond

energy.

impulse,

POWER

2.0 this

imposed

presents

of fusion

systems.

involved.

electrical

planetary

as large

on fusion

SPECIFIC

is clearly

to permit

combined

stationary

parameter,

and flight

in Section

distances,

As shown

is key for

reasonable

operational

A specific

to develop

REACTORS

is preferred

high specific

with variable

and electrical

of 10 kW/kg

use of space

little functional

goal power

for propulsion

characteristics,

the application

the successful

but could serve

and Requirements

those anticipated

planetary missions.

is the minimum value

the maximum attainable

This section for reactors

needed the distances

6.0 Flight System Considerations

requirements to space missions.

Values much below 1 kW/kg would provide

to the Oort Cloud (Orbital

Three consideration:

10,000 N to 50,000 N

low: 1 N to 10,000 N

stage to Alpha

to provide bodies.

operating This

vehicles Centauri.

to the low thrust,

from the surface

multiple and

that of existing

level will power

the high thrust

to be of value

for high thrust

The mid-range

and to realize

an economical

or orbit-to-orbit

N to 500,000

must exceed

to the OMV

in this study.

the massive,

characteristics

high specific

the system’s

is analogous

(b) medium:

be achieved,

development

stage-to-orbit

Maneuvering

of planetary

considering

low vehicle

If a reactor

is expected

performance

established

capabilities

To achieve

low thrust

light-weight,

appropriate

considered

somewhat

from the

arbitrarily

SPECIFIC

the solar

IMPULSE

capability

planetary

category.

THRUST

Vehicle),

missions

a single

use for

effective

and lift

beyond

volume

applies

system

vehicle

50,000

aircraft

power,

having

Space

thrust

levels

power

return

range

thrust

mass

level,

6.1.3

6.1.2

high:

level

Tug,

high

The

and

can

low

6-2

are

(a)

for

(c)

specific

indicate

mission.

systems

impulse.

changes

a mass

sufficient

Although

is stated

optimized

illustrative

or provide

dependent,

to warrant

To exceed

on a scale

the specific

expenditures.

costs. for

at a reduced

a requirement

as an example

one would never

Isp for it optimized

the developmental

a range to reflect

at 55,000 seconds;

the same capability

to over 106 seconds.

valued to provide

to about 10,000 seconds.

impulse must be capable

the average it decreased

The specific ranging

the averaged are presented

but The optimized

that would imply fusion system performance

performance, Isp>10,000 the research

6.0 Flight System Considerations and Requirements

the Manned Mars Mission in the optimal

total overall ion to to rocket

systems fusion of sufficient magnitude From a fission

that would sec at 2 N thrust and developmental (NERVA)

From the calculations variable highly being impulse requirements from less than 104 seconds

in this study, to provide in the study were strongly mission

propulsion system cost engine produce warrant engine point of reference in excess of an Isp of 860 sec at a 40,000 N level of thrust.

Consider variations year mission, year mission, Isp is actually report values Those values apply to a reactor propulsion we were to fly a specific power propulsion greater flight 170,000 seconds

To achieve a mass optimized reactor design, the purely aneutronic fuel cycles would be preferred if they could produce energy breakeven and sufficiently high Lacking that option the next power density to meet mission requirements. preferred is deuterium - helium-3. Refer to Section 7.1.

This value should be as high as possible, and stable the bounds order of 90% are considered to be possible, determine

If then an Isp of the vehicle mass for a it is more than of 3 x 106

the range in fly the ten for the 0.44 “value” of In this the ranges.

total system weight within on the to

of system specific system of 10 kW/kg,

examples the variation power of 1 kW/kg.

is those producing the minimum neutron flux.

seconds. for the stellar mission.

except a better understanding

by comparison, noted was in excess

in the spacecraft’s for some

than 30,000 seconds will be required

but no study has been performed

to minimize plasma

For the 10 year mission,

a minimum acceptable

time of 0.44 years.

FUEL CYCLE

The greatest

performance.

Isp demand

to optimize

selection

of safe,

velocity.

reliable,

Values

where

BETA

value.

6.1.4

6.1.5

That

6-3

the

are

The

and

level

6.1.7

6.1.6

power

values

steady

design

plasma

ranges

starting

desired

Mission

mission

in-space

scheme.

Similarly,

impulse.

ease of

analyses

electrical

definitive

IGNITION

operation

performed

a variable

to and

THROTTLE

from flight

operational

temperature

and details

for overall

requirements

CAPABILITY

and specific

need to be

to establish

in the thrust

fuel selection

upon effect

requirements.

trade studies.

and minimum

The minimum

fuel economy.

and to reduce

state operation

and preliminary

and Requirements

in the mission’s

system, mission,

system demands

are considerations

to meet efficient

that will be defined

output will be called

variations reactor

of the reactor design,

is used, which is yet

to vary to match changes

inert mass. the plasma

6.0 Flight System Considerations

system by the choice

The reactor power output will be expected

simplify This will be determined confinement

power 275 MW using a (zplo/0.44 rendezvous

from the system user’s perspective,

the need is to design the reactor

(Alpha to the specific

completion the magnitude

Many of the planetary missions

range of the vehicle may have.

system were of

of the first stage power output

The design must also provide

and the effect on plasma

take on new dimensions.

by the individual mission

The In addition

is the most demanding.

by system constraints,

ignition, and shutdown

which could disrupt

the stellar missions

a 2.8 TW jet power

using a 50 MW jet

to be accomplished

allowing possible,

to be determined,

will be a function

If a o_plo0 fusion

and the specific

to 7 GW while

these missions.

design features,

analyzed were

to 2 diminishes

levels will be

the operational

on the 4-stage

the propulsion

of the mission

characteristics.

system being

to instabilities

system while

commensurate

characteristics

in 244 years.

Mars mission

the plasma’s

accomplished

the reactor’s

225 MW for

The manned

requirements

the mission

the number

is a reactor

of 10 kW/kg

to deviations

the present

are defined

to minimize

A reduction

requirement

The power

dependence

propulsion

STABILITY

is 28 TW.

A specific

dependent

of stages

and time

capability.

sensitivity

as mass,

with the

functions,

PLASMA

reactor’s

hardware

Centauri)

variable.

a stage

required

allowing

Whether

(xpl/0.44

designs

stability

mission

stability

POWER

is also

stability,

margins

decided

Plasma

system.

in 308

pulsed

places

LEVEL

if any,

factor.

Power

design

stellar

power

levels

power

years.

power

stage

there

flown

time,

6.1.8

6.1.9

such

etc.,

that

and

The

first

the

6-4

for

the

any

fuel

and

The

vary

data

level

such

have

need

other

could

levels

power

desire

phase

driver.

output

6.1.10

restart

traded

should

design

profile.

energy

vehicle

reactor

system

Hence,

Restart

running

system.

produce

required

POWER

electrical

as well.

as flight

identified

No such

megawatt

consistent

spacecraft

objectives,

generation

to a level

an output

equipment,

for storage

the reactor

the means

to produce

the reactor

continuously

of electrical

for electrical

life through

VARIABILITY

of a mission

is considered

ELECTRICAL

transmissions,

power for

some means

the propulsive

be anticipated.

is to conserve

and to extend

time, Av, etc.

are continuously

against mission

stellar missions.

to be the power

and the vehicle’s

The high reactor

required such

with the mission’s

would electrical

for a machine

of up to 25-30 MW was

not be optimal unless power

6.0 Flight System Considerations and Requirements

on the vehicle mass.

fuel, and the losses

fuel with a minimum

RECIRCULATION

and is therefore

use a minimum

or, alternatively,

is an extremely

in both modes

in the exhaust

The minimum

simultaneously.

high reliability

are preferred

autonomously,

of a valuable

an efficiency

is consistent

a propulsion

be provided

is the goal.

OPERATION

EFFICIENCY

of significant

or a power

the means

performance

one worthy

the reactor

recirculating

to retrieve

is a waste

to operate

the fusion

is desired

Therefore,

parameter

viewpoint.

Unburned

A simple

additional

with the

unburned

operating

utilization

capability

attention.

in either

a highly

research

provided

POWER

possess

inherent

burdens

Designs

efficient

vehicle,

use of

design,

system

reactor

power.

control

MODE

should

create

safety,

design

overall

MASS

critical

6.1.11

6.1.12

6.1.13

6.1.14

DUAL

power

which

either

mode

while

such

flight

crew

burn

from

that,

high

load

This

fuel

that

and

fuel

6-5

the

for

life

out

time

star.

LIFE

mode

gains.

6.1.17

6.1.16

6.1.15

reactor

burning

needed

science

MODES

required

reliability

FAILURE

for space

disruption

exploration

to accept

capabilities

operational

equipment

is preferred

any single

for a round

trip Manned

A continuous

TOLERANCE

is 4 months.

is mandatory.

A progression

The minimum

Mars Mission

to the nearest

The capability

in requirements

failure without

up to 50 years

OF OPERATION

safety to man or on-board

6.0 Flight System Considerations and Requirements

The reactor must

in performance

ENVIRONMENT

of the above

of operation

requirements

environment.

be capable

in a space

The status

is provided

SUMMARY

in Table

SPACE

reactor

6.1.18

6.1.19

space

6-1.

6-6

(a)

6.0

key

6-1.

Beta

Little

flight

6.1.5

6.1.2

6.1.1

6.1.4

None

fusion

space

power

status

reactor

Thrust:

TABLE

impulse

Specific

Prior or

powered

to meet

STATUS

required.

Research

performed

necessary

Comments

parameters

Fuel cycle

RESEARCH

PARAMETER

active research

space-relevant

6.1.3 Specific

and Requirements

required. analysis

SPACE REACTOR

system requirements.

low: 1 N to 10,000 N

Has not been addressed.

Flight System Considerations

(b) medium:10,000 N to 50,000 N

Limited study. Requires burning of fuels.

Limited conceptual work. Experiments Has not been addressed.

Limited conceptual work. Experiments Considerable performed. Burn experiments required.

Burn experiments Lacks analysis of the space band of interest. Has not been addressed. Burn experiments Has not been addressed.

Very limited study. Requires burning of fuels demonstration. A function of the reactor design. Very limited study. Requires burning of fuels demonstration.

Very limited analysis performed. required. Has not been addressed.

Has not been addressed. To follow net power demonstration Has not been addressed.

Varies with fuel selection and reactor design.

Very limited study. Requires burning of fuels demonstration.

Limited analysis done. Burn experiments

Work will follow net power demonstration

program is or has pursued

Has not been addressed.

to either work which

program pursued.

the NASA fusion

The NASA work

program exists.

or, alternatively,

DOE terrestrial

1 NO space

is presented

of operation

Recirculation

work which

Dual mode

Experiments

in Appendix

environment

performed

Efficiency

research”

or active

operation

produced

capability

variability

tolerance

Electrical

in depth

required.

neutrons

research

Throttle

Plasma

stability

Ignition

Low/no

Failure

Modes

Space

Power

6.1.10

6.1.11

6.1.12

6.1.13

6.1.14

6.1.15

6.1.16

6.1.17

6.1.18

power

fusion

refers

“Prior

Mass

6-7

6.1.6

6.1.7

6.1.8

6.1.9

level

the

its

6.2

and

THE

6.2.1

WITH

power

(SFR).

power

system

section

should

vehicle.

SPACE

FLIGHT

FUSION

POWER

restarts.

functions

SYSTEM

examines

VEHICLE

electrical

RESTART

REACTOR

addresses

of reactor

the fusion

INTERFACE

CAPABILITY

Recirculating

the vehicle’s

with the flight

is no inherent

It will probably

and inert mass

a key capability

to the successful

and Requirements

the system aspects

limit on the number

This interfacing

6.0 Flight System Considerations

This requirement Fusion Reactor

Start-up should be minimized.

The goal be quick and simple.

heat a low mass cooling system.

in determining vehicle’s mission

the greatest the key challenges

missions) while while maintaining

use of a Space in establishing

vehicle the and sufficiency

in the space the

is the goal. While this does

It will be a key subsystem

time, the neutron

be the major parameter

have program.

the overall mass

liquid helium fuel

the fuel minimizing

appear selection

by the system’s

created of

and that which

as establishing

RADIOACTIVITY

characteristics

is to provide

environmental

both natural

for a period

requirement.

performance

is internally

CAPABILITY

to produce

its intended

and threat

specification

operational

to fulfilling

the extent

anticipated

objectives.

Operational

or neutron

the fusion

for stellar

exposures

spacecraft

STORAGE

operation.

(centuries

generated

exposure,

A vehicle,

subjected

challenge

capability

No direct

technical

of years

is aided

operating

as well

exposed

typically

required

duration,

to store

radiation

induced

possible

will be

storage

solution

vehicle

ionizing

mission

by the

present

energy

to the

regard

design

during

being

FUEL

6.2.2

6.2.3

after

with

One

flux.

and

the

6-8

not

the

for

will

the

any

that

with

This

from

each

6.2.4

cycle

here,

value

result

reuse

which

fusion

is too

cycles

clearly

dictate

should

reuses

degree

set of

But at

classes

to that

mission

number

neutron

REUSE

induced

vehicles

duration

damage

number,

required

a value

enhance

essential

A large

for D-T.

capability

of space

otherwise

designed.

of D-3He

objectives

compared

is readily

for which

a specific

technically

advantage

economics

technology

and flight

Economics

the reuse

specialized

penetration

achievable.

interactions

degradation

this phase

perspective.

from deep

life without

radioactivity.

of helium-3

for manned

for Manned

development,

to be used

it has been

refurbishment

being that

is anticipated

early would

For example,

to significantly

to accomplish

be developed,

Mars Missions

and the ensuing

and Requirements

The fuel selection

is due to reduced

high or even

40-50 is likely

in first wall material

frequency impulse

a be depending

number economic

substantial upon

suggested several

a realistic optimal

to establish represent

desired performance,

approximately of missions.

of confidence that

6.0 Flight System Considerations

times that a low specific

The system consumables. body.

mission to the Oort Cloud

A capability must be provided to make

Fission 1% to 3 % of

to a 100-year Obviously

assuming use reactor

the reactor, mission

from 1.5 to 8 years with

up to 50 GW jet power,

and to act as an energy

time of 5 and

life for a singular

or on an extraterrestrial

missions, jet power

are to be avoided

to refueling

power estimate

exceeds safety.

of a steady-state

but high power

equate years.

be serviceable

back where

the requisite

be designed

replenishment

requirements,

transmissions

of 4 x 105

the demand

requirements

the reactor.

to enhance

are longer,

the vehicle

an average

SERVICING

for mission

is selected.

STORAGE

the One

40 times.

a 20-year

the short

and 600

available

ENERGY

but with

in space

to Mars

for data

annually.

seconds,

assumes

impulses

reservoir

missions

reactor’s

biannual

required

includes

systems

will be

to start

indicate

impulse

reactor,

science

reactor

specific

restarts

energy

phases

is that

varying

applies

supply.

system

reactor

reuses

of all

output

higher

where

power

stellar

would

either

lower

times

flying

twice

cycle

6.2.5

6.2.6

must

solar

flight

level

forth

duty

This

and

if a

life,

For

6-9

the

trip

for

the

For

and

LIFE

SIZE

6.2.8

6.2.7

ease

goal,

class

Mars,

costs

years

range

where

years,

design,

should

science

vehicle

life for

serving

be the

devices

reduces

updated

airframe

vehicles

of orbital

Additional

warranted.

technology

operational

integration,

A minimum

the Earth,

the reactor

replacement

of 20 years

For aircraft,

performance.

those space

as workhorse

the planetary

in the vicinity

or 50 to 100

to approximately

life goal where

be a reasonable

drag and impacts

including manned

using modularized

missions, for

the burning duration

stellar allowance

the use rate is high.

For space envelope

to over of science

system on vehicle

as well as to maximize

concern. to minimize

flight, is particularly

flight the collection

time can and transmittal

size is not a particular in order critical

6.0 FlightSystemConsiderationsand Requirements

On orbit maintenance disassembly

some Use of staging

with the goal of minimization

capabilities as discussed

the Manned 6.2.4

is to avoid too, would

is a design for

requirement. return

substantially safety

and repair reactor

with in Sections

to verify the capability

such a flight system.

other key parameters

is still a consideration.

50 years per stage.

rate and minimized

out favorable

system design,

wear a more

match mission

energy Trades

of any pulsed

STEADY-STATE

MAINTENANCE

and reliability

vehicle mass

total supply

the enormous

For example,

and provides

requirements

is of utmost

are required

from fusion,

optimization,

a preference

performance

OPERATION

steady-state

like specific

configuration

system to

performance

is required

Even with

for D-3He

of vehicle

importance.

of a large

and 6.2.8.

is clearly

or steady

dynamics,

operations

reliability,

The goal

propulsion

categories

simplicity

to design

important

operation

in terms

a device

to Earth.

planetary,

reliability

are met.

enhances

preferred.

economic

flux will

in space

provided

operates

Analysis

VERSUS

PULSED

Whether

available

ignition,

system’s

dynamic

reduced

indicate

neutron

vehicle

control

present

Vehicle

overall

optimal

is not

system

of the

pulsed

power

MASS

6.2.10

6.2.11

fusion

mass,

stellar

trade.

which

Mars,

lower

since

state

data.

ease

6.2.9

meet

This,

plus

6-10

inert

and

For

the

for

rate.

result

thrust

6.2.12

power

POWER

reliability

repetition

function.

programs

dynamics

advantages

production,

to electrical

from frequent

CONVERSION

cost advantage

or by increasing

This also implies

follow the propulsion

rise and decay pulses

the inertial performance

AND TRANSPORTABILITY

over one which has transient

restarts in the pulsed systems.

A steady state system is considered

from multiple by either shaping

6.0 Flight System Considerations and Requirements

engines the thrust a short to that

of overlapping an option which could be accomplished the pulse

technique of course tail-off duration for the engine start-up transient. have inherent

This capability refers to the reactor serving initially as a propulsion system with the capability for conversion into an electrical power generation system after reaching orbit around a planet or moon. By making use of a single purpose in those are provided with an enormous reactor, The missions where large power requirements system can either be used in orbit or transported to a planet’s surface the subsequent use of large electrical power production. conversion dynamic loads, controls to permit operation under both modes, some of the parameters to be explored.

The goal coolant purposes and to minimize the radiator mass. burn heat soak-back. important characteristics. must be cooled to 4K while other hardware must be maintained warm to function without

remove conversion system. (Refer to Fig. 4.2.) For example, requires .-270 MW jet power output. A 440 MW reactor would produce level of charged

for This includes the post- is very thermal fluids is cryogenic helium which sufficiently It will be necessary to

from the reactor and from the direct power the Manned Mars Mission that power

The means to quickly and safely terminate reactor system’s burning should be provided as a contingency capability.

Analysis of the spacecraft’s a system capable

to weight, etc.), refueling, maintenance,

the the on-board etc. are

For example, one of the critical

imposing large power drains.

of yielding the necessary

requiring the expenditure

a large quantity of heat

The ease of operational

dissipation requirement

is to avoid designs

is thus 132 MW.

AND COOLING

of consumables

the capability

to withstand

EMERGENCY

in achieving

SHUTDOWN

The D-3He

(Av, thrust

(Fig. 4.2).

BALANCE

balance

thermal

particle

energy

6-1 1

6.2.13

6.2.14

HEAT

for

the

are

The

that

prior

long

high

AND

ultra

wear

such

goal.

parts

State

SELF

6.2.17

6.2.15

6.2.16

space

SOLID

design

should

STATE

reactor

subject

contain

features

achieve

demand

required

distance

a “Solid

vehicle’s

reliability

to control

approach.

the errant

operational

to erosive

Propulsion”

of initiating

requirement

to recognize

requirements

OPERATIONS

PROPULSION

DIAGNOSTICS

is the design

CORRECTIONS

System (SSP)

an autonomous

life and great

system design

or components

and Requirements

The SSP concept

The system should

moving electrodes.

to the onset of a failure.

an adverse parameter

trend and must be capable

6.0 Flight System Considerations

the diagnostics the means

The clown schemes and increase

as well as the population spacecraft,

in mind that operational concept. of a technical

level, but accessibility is not a planned

Complex for of radiation

on-board and non-fusion

vehicles. be the preferred

simplicity may Maintenance

for acceptance should

in the space operation.

failures, the loss conditions.

from any reactor will have

or be set at a

the objective situation

either of a system

of avoiding under

minimal maintenance

should not be adversely

is a must, even where

within the background

flux a careful

Freedom which will

fall within acceptable

of the reactor must

the vehicle mass.

keeping rejection

neutron exist,

of either these

allow for simple

of risk to those

to its operation,

like the Space

cool fusion

effect. Where

of its criticality,

The operation

REDUNDANCY

or operational,

levels would

the radiation

for a simple

will dampen

requirements

as a whole.

The system,

a hazardous

be a cause

environment

be designed

be exposed

for NERVA

Operational

restrictions

operations.

to provide

to tolerate

a minimum

or causing

like those

equipment

emissions

be made

ooerati0n,

Similarly,

a similar

by fusion

selection

on-board

to occur

hardware

powered

because

required

SAFETY

Keeping

degrees

affected

because

support

options

Station

design

should

space

6.2.18

6.2.19

must

goal.

6-12

with

two

nor

level.

either

effect,

6.2.21

6.2.20

should

and of

SPACE

fashion.

in order

particles

a matter

STATION

in general

generating

installation.

environment

not provide

be designed

large fusion

requirements.

The operation

to the Earth’s

of a temporary

ENVIRONMENT

COMPATIBILITY

be accomplished

of environmental

to be compatible

due to the operation

to space contamination

is the effect of neutrons

of any power plant on any

if required, for a new orbital

of have an adverse

an impact in an unacceptable

with Space Station new space

For example, would lingering or

6.0 Flight System Considerations and Requirements

assembly, to avoid the requirement

become added to Earth’s environment

to eventually There should be no radioactivity

to fully use its resources without Orbital

The fusion spacecraft Freedom (SSF) logistics by the SSF facility

One particular ions on the upper atmospheric vehicles.

Its operation contribute focus chemistry charged nature, upon Earth communications? planet can be anticipated concern. the background

System reliability is typically achieved by the design of redundant hardware, and the reactor design would have to lend itself to that feature. Alternatively, use of significantly could be achieved without of probably

System qualification testing will be required in a space operational environment and flight and probably

to be associated to Earth plus the reflight back to orbit costs suggests

The mass, returning remain on orbit should

an Earth based method of testing and qualification

operational experience accelerated

costs, and component

The means for stress testing and

To minimize reactor

the mean time between

such that a high degree

size, the reactor

redundancy failure

that can be anticipated

the reactor and vehicle.

only be met by carefully

life testing are needed.

AND QUALIFICATION

large design margins

have been obtained.

based techniques.

flight operational

the life time of

with permanent

not ultimately

is a challenge

be compatible

Demonstration

to the space

RELIABILITY

is preferred

environment.

until years

The design

experience.

acceptable.

with it

and costs

is likewise

throughout

to space

controlled

VEHICLE

TESTING

exposure

that will

of years

reliability

attained

DESIGN

BASED

designs

SPACE

(MTBF)

of the

6.2.22

6.2.23

6.2.24

above

flight

6-13

test

that

the

but

the

life,

and

less

only

return

space

undue

6.2.26

6.2.25

critical

range.

design

should

All of

reactor

vehicle

outside

dispose

options.

removal

Perhaps

Disposal

in order

it entails

to avoid

problems

essential,

a means

economics

its useful

completion

DISPOSAL

completion.

requirement

components

the start of

be an initial

ECONOMICS

the program.

its life cycle

is necessary.

aforementioned

this parameter

to satisfactorily

and Requirements

has no significance.

to send to Earth

desirable, such that

the or storage

its hazard are other,

will It, however,

time replacement

simple Disassembly

updated be addressed

6.0 Flight System Considerations

of on the moon

be continuously should

burn maneuver and

replacement are requirements.

can be accomplished and accidents

system’s by a high degree

NASA system design

be minimized operational

human mandatory.

it will be incumbent

the development

and contingent

which costs

implementation

and therefore

to thoroughly

a philosophy

for economy

of autonomy

To be cost

costs must

is presented

of a space

for nominal

components

The status

investment,

understand

operations.

operational

to reduce

propulsion

spacecraft

parameter

and the

to adopt

of highly

for each

hardware

comprise

effective,

STATUS

establish

in Table

research

as well

due to

system,

system.

as the

criteria,

reliable

system

others,

a very

overall

6.2.27

power

fusion

error.

initial

upon

Also,

large

ease

flight

6-14

final

6-2.

The

and

the

will

Life

Size

Very

6.2.9

6.2.8

6.2.7

6.2.6

6.2.5

6.2.4

6.2.3

6.2.2

6.2.1

Mass

None

6.2.13

6.2.12

6.2.11

limited

Reuse

Servicing

performed

Parameter

Radioactivity

Energy storage

Research status

and Requirements

6.2.10 Maintenance

Fuel storage capability

Space restart capability

Prior or active research1

6.0 Flight System Considerations

Power conversion and transportability

Pulsed versus steady state operation

TABLE 6-2. Research status of key fusion system requirements.

a space fusion R&D program is manifested by the absence of definitive data on to provide for a critical parameters. force fusion space If a fusion behind

The system analysis shows solution of which will not be researched in the terrestrial program.

The principal motivating it provides.

reactor start/restart other

is required to start it, a significant

tasks need to be addressed,

the The need for

6.2.14 Heat balance and cooling

Space based vehicle design

than for performance

One of the greatest

Testing and qualification

is the requirement

is the safety that

that very difficult

Solid State propulsion

is lost in safety,

6.2.17 Operations

Self diagnostics

and corrections

SUMMARY

advantage

capability.

Redundancy

Environment

Emergency

Economics

shutdown

Reliability

reactor

Disposal

fission

Safety

6.2.15

6.2.16

6.2.18

6.2.19

6.2.20

6.2.21

6.2.22

6.2.23

6.2.24

6.2.25

6-15

6.3

for

will

that

very

Two

other

range

space

years.

include

offering

designs

program

flexibility,

durations

important

operations

and firing

applications

a minimum

can serve.

over many

maintenance

not address

environmental

the terrestrial

and in the wide

and Requirements

operational fusion

6.0 Flight System Considerations

of space mission system tasks which

6-16

7.0

has

FUEL

under

design

energy

reactor

FUSION

electrical

OPTIONS

REACTORS

the options

for a space

The national

FOR SPACE

The absence

AND DESIGN

for commercial

as the preference,

power production.

and optima1 fuels

considers the current

based upon the known features

inventory of fusion experiments,

of a review of the

(SFR) designs and test data necessitated

and a fairly limited experimental data base.

reactor and the reactor designs

fusion energy program is dedicated to the terrestrial application of

Each application operates commonalities also exist will differ from the terrestrial

This section application, which burn those fuels and which are most likely to have space applicability.

fusion space fusion terrestrial designs with the objective of matching the space system requirements lacking a Consequently, presented in Section 6.0 with the terrestrial designs. fusion reactor design studies having space fusion activity, only a few conceptual potential for space applications emerged during this review. All of those studies which have been conducted for space have been very limited, and the level of detail has been low. One fusion reactor concept emerged

One possible land, based power that application propulsion, for that space which differ and can, therefore, to deal with and to resolve. issues regime. operational different entirely application may, for the terrestrial

the lead to a SFR design. contender program is the tokamak. large mass and low beta which results in unacceptably

its use as a lunar, or any In in Appendix B. laser source Except design. for approaches These SFR’s will be different set of physics

Therefore, terrestrial For example, the leading But due to the tokamak’s low specific expected

use, NASA will, of necessity, from those for terrestrial

issues the two applications.

power of a terrestrial design

One such concept serves

the criteria for space reactor utilization.

Their operational The solutions

contribute for the terrestrial

that being a unique space application

terrestrial which although

for characteristics

reactors as a consequence of:

to have a new and different

program will not necessarily

under to resolve

source. the reactor

for mission applications.

of physics to or

the mode of operation

its use for on-board

as a multimegawatt

system problems

apply to space.

and therefore

the operational

not necessarily

be anticipated

the resolution

consideration

in application,

environments,

differences

requirements

is presented

and power

are in an

one must

application

propulsion

for fusion

therefore,

problems

possible

between

remains,

designs

tokamak

physics

to meet

namely,

unique

employ

power,

power.

is not

realize

limited

flight

SFR

and

that

7-1

for

7.1

FUEL

status

power

reactor

potential

terrestrial

for space,

as energy

for space.

8 provides

is reviewed

SELECTION

the preferred

those preferred

The three easiest

and program options

This section analyzes

of candidate Their

TABLE 7-1. Preferred fuel characteristics.

and propulsion the major

devices a summary design

7.0 Fuel and Design Options for Space Fusion Reactors

is a brief description application

considered. funded DOE for

for space of program status approach

first deals with the fuel of preference next

This section Undertaken having applicability Section programs, consideration.

for space and its availability. designs and their

to ignite fuel The features necessary for space applications are presented

Fusion reactions were discussed in Section 4.0. in Table 4-1b. were presented options for space. in Table 7-1:

Ease of Can be readily engineered for space use Long space storage life Available to meet mission requirements High power output Space storable

a. Nonradioactive b. No neutrons in the flux c. Non toxic d. Non-flammable e. No ionizing radiation

a. Reusable design permitted b. Minimal maintenance c. Minimal mass

d. Minimal environmental e. Low mission fuel costs reliability f. Flight

Three tritium, deuterium-3He,

a. High power density b. Charged particles

for space use: deuterium-

fuels and their availability

and deuterium-deuterium.

reactor designs- gigawatts

FUEL OPTIONS

are considered

Performance
Economics

d. e. f. g. h.

Safety

SPACE

ignition

impact

7.1.1

7-2

hi I,—

for

the

fuel

has

pair

This

high

is its

as a

which

would

fusion

suited

tritium

power

shows

<(_v>,

Ideally

energy

7.1.1.1

density

relative

plasma

physics

difficult.

its use

Another

reaction

favoring

appears

greatest

program

received

although

attention

breeding

terrestrial

in space

compares

availability,

application.

to be highly

is its superior

is the easiest

from the D-T

The Another

of attractive

DEUTERIUM-TRITIUM

reactivity, fuels.

properties. function

generation reaction

the to space.

Refer temperature

very demonstrate.

yield consideration

its it with other

the D-T reaction feature

to Fig. 7.1(Mil76) and which

7.0 Fuel and Design Options for Space Fusion Reactors

radiation as with an RTG. But public concern will be important, of application in the final

using fission power sources are now subjected. those is the circumvention the public from a large tritium payload

tritium for Low Earth Orbit The

The fuel significant quantities accepted maintained

One motivating problems. release

relief payloads for penalty a launch

may not be be will public

in the event of are payloads

program would be essential.

nearly and massive

be a severe in the VISTA

factor The weight

to protect accident

to tritium are several.

penalty approach.

a very extensive

tritium are required

and will offer only

(LEO) neutron

is an undetermined

designed massive

As a minimum,

at safe orbital

The drawbacks

It is radioactive

as determined

considerations

educational

the use of

Radioactive

materials

activated

altitudes.

from the

analysis.

conditions,

to which

expensive

to worse

quantities

transport

nowhere

quantity.

TEMPERATURE,

science

space

Fig. 7.1.

reactivity

energy

hazard

limited

during

safety

space

fusion

(Mii67).

which

could

Fusion

flight

case

orbit

PLASM/_

7-3

fuel

keV

I0 3

t0 z

10”

]-3

,el

I—

LLI

6Li + n _TLi _T + 4He.

7.0 FuelandDesignOptionsfor SpaceFusionReactors

An alternative is to breed tritium using breeding fusion reactor designs. These is the preferred have been given consideration. A lithium blanket concept approach:

Tritium’s 12.3 year half-life will ensure the need for a continual requirement for tritium production from lithium, a process requiring fission reactors or D-T fusion reactors and the attendant environmental impacts. Because it cannot be stored indefinitely due to radioactive decay, the production facilities must be capable of time the United States producing large quantities quickly. At the present production rate is estimated at 5 kg annually from the Savannah River weapons plant. The VISTA spacecraft used 40 MT of fuel for one manned VISTA Mars mission, half of which is assumed to be tritium. That would require the fabrication of ~4,000 Savannah River fission reactors to meet the fuel demand for that one mission on an annual basis.

Mass in space flight programs is always placed there at a performance premium. As discussed earlier, 80% of the energy produced by this reaction resides in neutrons. Extraction of useful energy from neutrons is only achievable thermally using devices which typically operate at efficiencies not than 40%. Cooling mechanisms are required to expel much greater the In space, this means an added mass penalty cost for radiators residual heat. and consequently, a performance penalty. Probably the most significant concern is the high neutron flux of ~3 million watts per square meter (Hol88). This high neutron flux damages materials at a rate greater than an order of the magnitude higher than in fission reactors. Neutron bombardment of reactor’s first inner wall leads to its demise in a time period that may be as brief as one year. There will be significant first wall radioactivity from the neutron activation products. These include a wide range of radioactive elements as discussed in the MIT safety and ESECOM studies (Section 9). The options are either total reactor disassembly there for in orbit or replacement of the exposed hardware and its disposal. Orbital disassembly of the a large device, a difficult operation in the space environment without radioactivity factor, will necessarily be accomplished remotely by sophisticated robotics having an advanced degree of artificial That entire operation will also require some very well thought out contingency capability in order to be safely conducted - a very expensive operation.

Obviously for a 200-plus year mission duration, tritium’s short half life eliminates it as a fuel of consideration unless a mass efficient means of tritium production is provided aboard the spacecraft. Otherwise, the Av for the spacecraft and its braking propulsive maneuvers or electrical power generation occurring 200- 300 years after lift off would not be possible at the time of need, if tritium were used.

replacement

intelligence.

reactor

7-4

for

not

fuel.

heat

tritium,

7.1.1.2

property

rejection

resultant

although

systems.

eliminate

Therefore,

the onset.

particularly

generation,

radioactive.

Chemically,

the half-life

does has

the preferred

not eliminate

the continual

the magnitude

space missions

those problems,

it since deuterium

of being That

The large penalties

the stellar missions

or tritium. but does

an inert fuel cycle

reduce the risk or defer

D EUTER IU M-H ELI UM-3

fuel without reduces

is not a problem with helium-3.

the is also used.

helium-3 the flammability

desirable of hydrogen hazard

is not tritium due to decay

Tritium is an option for solar system exploration,

power tritium breeding additions

for electrical massive and mass substantially.

7.0 FuelandDesignOptionsfor Space Fusion Reactors

Unlike problem of on very extended

replacement By comparison, tritium would make it useless

systems The decay heat also requires the means for heat

The D-3He fuel cycle, while it does not entirely very substantially the very hazards flammability

Dr. Logan examined comparisons assuming other inherent presented D-3He over D-T for a wide range of 13.

factor and that to adhere to the etc. His results are of

Fig. 7.2. Specific mass characteristics of D-3He compared to D-T for a wide range of _.

of nature regarding material the better

reactor design parameters were left unconstrained

for neutron are rejection.

between the maximum heat

D-T and D-3He. transfer

(Log88) is the design

without shielding reduced

specific mass characteristics

relative merit by comparing

A model was developed

in Fig. 7.2 which shows

limiting except

specific mass

the question

properties,

limitations

P_ (MWth)

[3 = 0.05°/,

that

7-5

= 0.05%

Plasma

D-3He,

Power,

2x104

. D-T,

lx104

3x10

lx10

Q. _

_o)

for

costs.

one at

Atomics

appears

(assuming

Laboratory

operational

The space

per pound

of payload

to ~$4,000

is particularly

of magnitude

the Astronautics

to be an excellent

Systems Command.

than ground operational

to decrease Shuttle

topic was recently examined

in developing in time.

The same conclusion was reached (Hal89).

launch costs decrease orbital

costs The investment this point

7.0 FuelandDesignOptionsfor SpaceFusionReactors

from $320M to $250M to launch are orders

lowers the radiation hazard as well. Maintenance on orbit

the D-3He fuel by McDonnell Douglas Space Systems the Air Force

The substantially reduced neutron flux of 0.09 megawatts per square meter (Hol88) is significantly simplified from the reductions in the first wall flux. Consequently, the final parts of the solution - the engineering and performance aspects - are very significantly simplified by the selection of D-3He. Simplifications to the system hardware and flight operations represent significant savings to the space program where the engineering and managerial costs to achieve flight readiness of programs are enormous, where the transportation costs to orbit are the anticipated anticipated

MT into LEO), and where higher physics preference Co. and General

are products The D-3He fuel cycle them as bleed off charged more than particles namely, 95% of directly to alpha and mass propulsion the neutron inefficiencies model flux can be reduced recently back to at least 1976 (Mil76) and to the NASA research work (Appendix A). With regard to fuel space its availability, purposes, It has to be manufactured

on one tenth the is being tritium in the D-T lithium For those solar systems missions To fly one slightly

For Earth. As a by-product tritium. cost of explored as discussed cycle may be cheaper small where relatively manned mission

applications, of of helium-3 in Section

thermal parameters upon a sophisticated can be traced

The significant compared demonstrate. greater ensue.

thrust by propelling nozzle. in the form of charged

For fuel options except helium-3.

of which can be converted usual

particles which readily from the plasma through

difficult is the plasma’s could

than helium-3 mining. fuel masses are used,

greater than one kg. there are no attractive

energy and protons, electrical

the physics ignition temperature

is present the energy power

to approximately (Ker89),

can be mined in Section

and the higher of quality

on the moon is an option which

by fission or D-T fusion reactors.

helium-3 as discussed

of D-3He is the greater difficulty

the long duration Oort Cloud

1%, based the concepts

sensitivity It will demand

By the proper use of design

fuel cost the helium-3

to Mars the mass of

and stellar missions,

since the reaction

ignition to

tritium production,

higher measures

is not an issue.

to contaminants

with the higher

is the scarcity

the reaction’s

Compounded

disadvantage

tritium can

and losses.

Fortuitously,

is presently

of helium-3

for not.

a magnetic

loss which

on airless

to achieve

developed

differently,

terrestrial

attractive

Breeding

particles,

is more

although

radiation

helium-3

particles

required

to D-T

produce

another

7.1.2.2.

control.

is only

without

bodies

Mining

and/or

stated

7.1.2,

7-6

the

but

other

production

international

arrangements

law and space that an acceptable

7.0 FuelandDesignOptionsfor SpaceFusionReactors

(8) Existing suggest international various

Helium-3 has been reported to be available on the lunar surface in sufficient quantities that mining appears feasible (Wit86). A conference was held at Cleveland on April 25-26, 1988 to specifically address the possibility of lunar mining of Helium-3 and the feasibility of D-3He fusion reactions. While it was considered an enormous mining undertaking simply in terms of the mass of material moved, no technical obstacle was reported. One of the conclusions drawn in the NASA Lunar Helium-3 Workshop (anom88), as reported in the Executive Summary, was “that lunar mining of 3He is feasible.” The lunar is calculated to be ~109 kg (Wit86) based upon the lunar quantity present samples analyzed from the Apollo and Luna missions. Perhaps the greatest obstacle is legal, i.e., who owns the mineral rights to the moon, rather than technical issues, but that is presumed to constitute the least obstacle to the United States, and it appears to be surmountable (Bil89):

It is important the mining of (Mil88). the D-D reaction D-3He burning. One other alternative reaction:

whether on Jupiter, of helium-3 of which has not been addressed. has suggested A sufficient

capability, logistics NASA can take full advantage it for use on fusion powered the element

basis can be found for cooperative include system

There is a question There 10 22 kg, University Uranus

the helium-3 supply does not solely reside with recent attention Dr. Miley has given this subject

role in a fusion vehicle’s operations, there from the regolith and liquifying

and and Space Station Agreements.”

is a significant the recovery of Arizona and Neptune.

activities will assume a major extent of extracting

A minimal helium-3 helium-3 moon without

3He from the primary is by the

from the atmospheres is available

choice to lunar mining is the use of 3He produced

estimated too, Dr. John Lewis at

the lunar presence directly

of He3. of national mining

p + 6Li = 3He(2.3 MeV) + 4He(1.7 MeV).

to understand the lunar surface.

of from the lunar

supply which can be considered

on the Moon. by processing

to be the of on

precedents the Antarctic

experience; INMARSAT,

concerning amount

and the extraction

the (p 110).

The first alternate

of vehicles

can be attained

is “energetically

These laws;

by processing

the unburned

its availability

the reaction

is expected

the Moon

Agreement;

INTELSAT,

return of

(600 kg)

to Earth.

helium-3

of all of

quantity

viable.”

(Wit86)

at it.

Hence,

to the

space

types

cost,

least

that

7-7

187

(the

1.3/yr

Source

2OOO)

reactors

a. Natural

MRC sales

b. CANDU

b. Man-made

MRC inventory

Known reserves

Present storage

from reactors

He-3 content, kg

Natural gas wells

a test program.

quantity reference

EquivalePt MWe-(yr) la,_

a. U. S. Department of Energy

in a sufficient here for

to provide as Table 7-2.

TABLE 7-2. Terrestrial Resources of 3He (Ku187)

7.0 Fuel and Design Options for Space Fusion Reactors

Earth naturally Table 2 from Ku187 is reproduced

From the standpoint liquid conditions,

Helium-3 Helium-4 Hydrogen Deuterium Tritium

CANDU - Canadian Deuterium Uranium

MRC - Monsanto Research Corporation

fuel physical requiring

TABLE 7-3. Selected gas-temperature

3K 4K 22K 24K 26K

(b) Estimate (Wittenburg

Weapons stockpile (b)

(a) 10 MWt-yr/kg - 3He

transition temperatures

tritium by 23K,

liquid helium-3

for each are:

the gas-liquid

At standard

Table 7-3,

techniques.

et al., 1986)

properties,

transition,

is cooler

Production

superior

for fusion

Inventory

cooling

Annual

than

fuels.

15/yr

Total

13.4

year

7-8

239

2/yr

0.5

D-T

0.05

0.25

170”*

0.005

0.013

100.0

160.0

640.0

D-He 3

p_B 11

106, K*

density

MW/kg***

CAT D-D

of fuels.

Parameter

Fuel Options

Physics Merits

requirements.

in the selection

some measure

of compensation

System Performance

Plasma Temperature,

Relative production, %

TABLE 7-4. Comparisons

Engineering Desian Merits

Neutron flux, 1012, n/cm2/s

Relative Plasma Power Density,

of fusion fuel operating regimes.

of reduced data to be

offers weight and cooling

7.0 Fuel and Design Options for Space Fusion Reactors

in terms Table 7-4 compares

Its higher containment taken into consideration

Peak plasma power density ** Will not *** Useful power per unit mass

That compares water. by solar winds since the mean reaction time for D + H _ 3He takes 4 seconds the sun.

hydrogen estimated of deuterium formed by cosmic-spallation of (Eps71).

for deuterium as the terrestrial in the oceans. One interesting the moon would serve also as a as a by- of

the mining research the examination the results were not encouraging. reports that

The space program, possibility source product of considerable Unfortunately, of Technology,

program can use the same source resides in this study was whether

gas to be about 5 ppm. Taking into account

and if so, could its recovery turns

be accomplished out, the Apollo

of Dr. Epstein, California

i.e., considered for deuterium,

of the mean value of D/H in ocean

the D/H ratio 3 x 10-6.

of helium-3? during

to 157 ppm as representative

D EUTERI UM-D EUTERIUM

based upon contributions

the solar wind therefore

had not been anticipated

samples. Institute

ignite at this temperature

A large percentage

(almost wholly

the contribution

of solar wind

the abundant

concentration

is no larger

A maximum

has been

processes,

deuterium

this was

a matter

in lunar

probably

7.1.1.3

supply

origin)

As it

value

lunar

than

that

7-9

the

for

…”

the

that

The

end

just

may

ratio

than

note

than

THE

flight

least

flight

input

7.1.2

times

could

water

entire

1980;

FUEL

There

fusion

water.

is an

where

power

greater

contain

is, we

energy

authors

featured

a report

equates

Penzias,

a higher

terrestrial

prototype

abundant

that the

are not

American

objective

If correct,

deuterium

produced

indications

interested

elsewhere.

are some

100 times

SUMMARY

engineered

on Halley’s

found The

concentration

of deuterium

of molecules

DISCUSSION

and Epstein,

developmental

to the direct

of breakeven,

system with

the D/H ratio

“In the comets

like HCN is at

(Wanner, comets

average observed

According clouds

in the demonstration

the D-T aspects

1980).” deuterium

more by Robert

Whereas engineering

time must be considered,

to a report the D/H

(Ba188). in interstellar

interstellar “It has been

The Scientific that

hydrogen indicate of

(Rob81). at up to 1000

terrestrial data would concentration

7.0 Fuel and Design Options for Space Fusion Reactors

Comet. is from five to 10 times

provide are also included.

suitability. and experiments

reaction, designs would

“success” the completion

be conducted advantage.

program could be completed

for conceptual

It is quite conceivable

greater. preferably

physics are not.

and overview,

include the following:

preferably needed,

space concepts

Although studies

on those of greater

system have to

based on realistic

a comprehensive

to demonstrate

to the plasma.

and worldwide

two approaches

and principles

too: magnetic

DOE terrestrial

For higher.

the of the

to numerically

A few general

are discussed

CONFINEMENT

and we focus

characteristics

are presented

using D-3He

of 10 kW/kg

use can be

a preference

confinement.

performance

confinement

experiments

engineering

net power

D-T. trade

CONCEPTS

production.

a minimum

MAGNETIC

show the

this report

approaches

the D-3He

selection’s

accomplish

REACTOR

discussed

the DOE

is easier

developed

to space

indicates

1 kW/kg

non-DOE

missions,

different

interest.

mission

FUSION

account

relative

designs

plasma

portion

reactor

greater

specific

inertial

provide

section

system

below.

in this

funded

activity

before

stated,

should

° The

These

(MCF)

power

space

stellar

early,

value

order

7.2.1

solar

7-10

best

Two

The

and

that

fuel

the

7.2

the

for

thrust and

electrical power.

Recirculation power should be minimized.

7.0 FuelandDesignOptionsfor SpaceFusionReactors

It must be capable of burning the fuel cycle preferred, D-3He.

The design should permit a simple conversion to direct
A minimum reactor mass is essential. The major mass items are the magnet - particularly the structure for load carrying of the magnetic fields force as opposed to magnetic field producing plates - and the Reactor self neutron protective shield protecting the magnets. generated field designs have inherently improved specific power.

reactor design configurations have been considered by the A variety of terrestrial program. This section will briefly discuss the more significant terrestrial reactors and comment on candidate configurations for space fusion power and propulsion. The DOE’s program’s test progress, plus inherent characteristics of alternate confinement experiments, provide confidence in the belief that fusion systems can be developed for space on a relevant time scale. The following section provides an overview and examines the status of experiments on configurations with respect to the postulated requirements for a viable reactor.

officially the attractive

in Fig. 7.3. systems.

It combines The closed

The FRC is a high 13

a “compact of both

shown and linear

the external magnetic

is the Field-Reversed

machine some

good confinement

From this study,

field lines would

CONFIGURATION

be conducive

Configuration

for meeting

the plasma

REVERSED

7.2.1.1

applications

designated

the linear

for space

the most

promising

to direct

topology

provides

features

specific

toroidal

toroid,”

(FRC).

design

FIELD

thrust.

power

while

inner

7-11

field

beams

Neutral

Neutral beams

7.0 FuelandDesignOptionsfor SpaceFusionReactors

Fig. 7.3. Field-Reversed Configuration

steady the plasma

operation, are shown

the FRC uses

to establishing

and operates

in Fig. 7.4.

confinement,

configuration

and overall

applications

The steps

parameters

field coils

solenoidal

attractive

magnetic

Because

potential

compact

primarily

to very

density,

design.

plasma

13, the

(FRC).

should

power

space

good

state

7-12

high

lead

high

for

’

—/

x n

FRC

AND

(4)

(3)

(2)

(1)

7.0

AXIAL

RADIAL

geometry.

i:!

_PARATRIX

FIELD LINE

EQUILIBRIUM

‘_ii

CONNECTION

CONTRACTION

COMPRESSION

for Space

FIELD REVERSAL

Fusion Reactors

Fig. 7.4. Stages

Fuel and Design Options

PREIONIZA-TION (0)

i HWLCLO DPL

The main difficulty of development, There has been only a modest worldwide Alamos Spectra confinement concept fusion expensive. performed parameters

the Los of the alternate the FRC the other to be less has not been

the Because than many of is likely

the FRC is at an early stage are needed.

be noted that a FRC space the reactor

in 1990 and plans call in 1991.

It should and that as the tokamak.

is the clear magnetic fusion program.

shown in Fig. 7.5, for the terrestrial

has not advanced to Section 8.1.2.)

The tokamak, leader worldwide

was terminated experiment

is that experimentation

but for termination

lower power operational

in FY91 due to budget

so that extensive

the developmental

(DOE eliminated

research effort

the breakeven

characteristics

in evaluating

the concept

and testing

approaches

reductions).

in progress

Technology

of FRC plasma

experiment

TOKAMAK

research

options,

exhibits

reactor

7.2.1.2

toward

design

formation.

(Refer

fusion

steps

each

7-13

7.0 FuelandDesignOptionsforSpaceFusionReactors

’”:’°,.o”:

‘::oJ..:°

.°.,i iiiiii.

The key disadvantage the design very massive magnets and, hence,

can reach the physics in the fusion can reach the physics reactor’s

the tokamak with regard to space achieve

reactor add a plasma plasma electricity

is that extraction to add a separate

only low _ values, of A major effort

research parameters research parameters operational

tokamaks, whose primary toroidal

large tokamak there large tokamak

presently due to the insufficient

the ion temperature for an ignited

Historically, for values requirements

and then power some form of plasma

success confinement remains

that a sufficiently regime,

advanced fuel of preference.

in achieving time compared

for economical regime.

to the in the fusion

to a to these

extra mass and therefore

either exhaust energy

is that to field;

to directly the fusion

in reduced by UCLA,

system for conversion

has had considerable

A detailed

propulsion ARIES

an overall massive

for burning D-3He,

in order device

it will be necessary

reactor is higher

expected study

system efficiency.

that a sufficiently

tokamak feature

is not a suitable

and experiments

system results.

as in all other

design an

a “magnetic

on “advanced”

III, concluded

are expected

the magnetic

is increasing

considerable

ion thruster.

in terrestrial

is underway

and energy

the reactor

this design

to produce

little doubt

commercial

A difficulty

the space

community

to require

application

production

conducted

in March

tokamaks,

13values.

approach

utilization

to result

Tokamak

attractive

research

Both of

designs,

plasma.

nozzle”

leading

options

in this

power

There

doubt

thrust

7-14

that

are

but

for

/ /

‘X_

Coil

. __

Field

Legs

/_/

SC/TF

(AW)

Vessel

Return

(W,Mo)

Plasma

Toroldal

Magnetic

(As)

First Wall

(Z_c)

(AI)/Vacuum

/_:i::i _::i!:

Demountable

of LiH/Heavy

tier Conductor

7.2.1.3

(Bor87)

TORUS

for Neutron/Gamma

Coil Shield Metal

SPHERICAL

torus (Pen85),

shown in Fig. 7.6.

to space applications

variant called the spherical

Consideration a tokamak

has been given by Dr. Borowski

Rad,ationAtteouat,on__ /

7.0 Fuel and Design Options for Space Fusion Reactors

Attractive the possibility design magnets requirement with power supplies currently

the use of superconducting torus power

which and the mass associated torus program

based on This than the copper the eliminate

spherical for a large recirculating to run resistive

postulated neutron generation.

(Xp----> 5.75 kW/kg) were

There is no spherical

The tandem mirror,

Fig. 7.6. Spherical Torus.

to be attractive

the D-3He fuel

is the leading

and appears

in Fig. 7.7,

in operation.

configuration

of polarizing

to suppress

applications

parameters

preliminary

conceptual

for space

(including

TANDEM

MIRROR

magnets

(San88).

Field Poloidal Magnetic

designs

allowed

terrestrial

fraction

reactor

of most

7.2.1.4

designs,

shown

based

fusion

rather

linear

coils.

would

7-15

Scrape-Off

Insulation

PF Coils

Thermal

Current

Layer

(Aso)

’_

Region

Central

Direct

Cell Coils

Converter

Ftux Tube

Choke Coil

[END CELL ]

ICENTRAL CELL I

” Neutral Beam

for HHD StebM Iz_t[on

Hagnetic at Plasma Edge

Fig. 7.7. Tandem Mirror.

Electron Cyclotron Resonance Heating

7.0 Fuel and Design Options for Space Fusion Reactors

Design kW/kg, over energy mirror exists theoretical constraints research that supports and, although effort would be required to develop

thrust fusion the tandem program presently experimental because

toroid and shares with the lends itself to lower power designs, but it is at an

The Spheromak, FRC the desirable feature that early developmental

is a moderate has arisen to eliminate most of

for space is that only a very small for

values and the designs range to electricity.

the data base available. caused

budgetary the mirror into research in 1986

program and to concentrate tokamak

“moth balled” experiments a tandem mirror

there This situation of Energy

the mainline some important

power were the generation

accommodated impulses

on developing research

greater of direct of

with relying terrestrial

the tandem mirror’s

shown in Fig. 7.8,

is also a compact

the Department

A key difficulty

and for direct

SPHEROMAK

This decision

a substantial

its funding

of specific

conversion

essentially

for space.

program.

occurred

although

concept,

7.2.115

specific

remain,

a wide

readily

stage.

all of

7-16

than

and

for

Field

_81onket

Coil_ ”_”

[qudlt._um

version

A space

Fig. 7.8. Spheromak.

7.0 Fuel and Design Options for Space Fusion Reactors

two to five times allow the generation

United by the Department

Spheromak research of

the FRC, The

geometry effort

7.9) was the major

than of direct

pursued (Rot72).

that of thrust.

Lewis Research

would on the

the Spheromak

the spheromak

program was

Field Bumpy

The Electric

configuration

consideration

value also

the NASA

and found

and most

to warrant

ELECTRIC

spheromak

of Energy

for space

terminated

the FRC.

its similar

worldwide

examined

program

at a 13

Although

relatively

Center’s

in favor

(Bor87).

BUMPY

recently

TORUS

operate

present

(EFBT)

during

7.2.1.6

FIELD

space

States

Torus

fusion

would

small,

lower

been

(Fig.

7-17

has

the

of the EFBT concept

Fig. 7.9. Electric Field Bumpy Torus.

7.0 Fuel and Design Options for Space Fusion Reactors

The key benefits magnet geometry. the plasma concluded

and solenoidal fields to confine The program was as a

result of a reduced Agency budget. Appendix A (Sch91).

and to provide in 1978 when NASA terminated

(Fig. 7.10) was funded by DOE and was operated

The NASA program is discussed

This reactor National

electric and magnetic

are steady-state

the Oak Ridge

and stability.

This reactor

in depth in

for plasma

Laboratory.

endeavors

its fusion

combined

operation

research

BUMPY

TORUS

heating

7.2.1.7

ELMO

7-18

7.0 FuelandDesign Options for Space Fusion Reactors

is to The principle level, which in turn heats the few is one of research loss to

too, This, use rf heating the plasma steady effort, limitations, improve (BS), was proposed

state machine with 13values up to 0.5.

Fig. 7.10. ELMO Bumpy Torus (EBT).

of It is no longer

(Fig. 7.11) and the reversed-field

program include the stellarator

the initial EBT concept,

the Bumpy Square

to a high relativistic

a small worldwide

of funded.

state, primarily

due to problems

the DOE fusion

The significance

in the terrestrial

high 13reactors.

in overcoming

pinch (RFP).

configurations

the transport

A postulated

Some other

of electrons

is a steady

properties

presently

transport

research

although

pursued

inherent

OTHER

but not

part of

change

reactor

7.2.1.8

energy

is that

exists.

fusion

some

effort

MCF

ions.

7-19

this

Fig. 7.11. Stellarator.

7.0 FuelandDesignOptionsfor SpaceFusionReactors

The stellarator would operate steady-state substantially present massive developed terrestrial However, feasibility

Inertially confined energies, usually ion beams or lasers, onto a small outer surface of a fuel mass is ablated away under release, compressing the fuel

of large fusion fuel pellet target. The the rapid high energy thereby

equipment. data designs breakthroughs of

There are many other confinement but

associated a moderately present exist, massive.

sending a shock wave toward the center of the fuel pellet,

the magnetic large Although and

out of ones have been covered.

may occur which would for space applications.

concepts experimental devices would

from that of fractions both

facilities be intrinsically

fusion parameters (Fig. 7.12).

recent and most extensively

have not been performed*

recirculating these

is very large (massive).

funded developed

The RFP but

the national program,

to space applications

significant these

the specific

of concentration

on the principle

the tokamak,

the concepts

field needed

INERTIALLY

CONFINED

significantly

Conceptual

the most

concepts

operates

enhance

to meet

FUSION

reduces

designs

indicate

designs

plasma

require

power

(ICF)

7.2.2

have

base

7-20

and

that

but

_“t

LASER

Fig.

_uEt

7.12.

RAOiATION

(ICF).

Fusion

IMPI,.O OIAI G

Inertially

Confined

very

under

These

operate

reactors

achieving

7.0 Fuel and Design Options for Space Fusion Reactors

on the faith and enthusiasm one would

Because with D-T than with D-3He,

from the United States of

foreign by the Japanese,

is unclassified concepts.

ICF program has to be taken

6,000 MT was considered.

in) performance

than MCF. ago.

been met with matching

publicly one draws

It is not a new concept,

of energy concept

out maximizes

to Mars and returns

a 100 MT manned

by the Department

results with data,

of a gain greater

MT in 100 days,

question near

so in that sense

into consideration

The achievement

is now on the

by this concept.

to understanding

an initial mass

ICF as a viable

ICF to perform

D-T fuel cycle,

higher the

that assurance,

it having

ICF for space

the practicality

on the status

high densities

and predicted

and is being

in Fig. 2.13.

is considered

approximately

A conceptual

the principle

paradoxically,

to be better

as a fusion

a two week

interplanetary

is classified,

the Lawson

of satisfying

those who

classification

to examine

into space.

the VISTA

as are all

information,

conclusions

The thrust

of Energy.

is required

Microfusion

This work

parameters

understood

to escape

to energy

Laboratory

conducted

is difficult

It delivers

is funded

A vehicle

20 years

originated

Obtaining

Whatever

is shown

providing

the fuel

in more

is much

its strict

involved.

essential

including

neutrons

analysis.

missions

for very

“VISTA.”

a study

concept,

because

potential

a factor

pursued

allowing

success

of gain

payload

drawing

(Ort87).

minimal

Without

source.

periods

is one

nature.

vehicle

losses,

current

Facility

named

energy

facility,

criteria

having

in the

gravity

(LMF),

insight

recent

theory

vitality

Unlike

fusion

space

status

1,500

Great

taken

Much

freely

MCF,

pellet

using

times

term.

(ratio

been

short

have

high,

laser

time.

least

stay.

level

7-21

than

gain

was

The

and

one

has

this

key

the

for

its

define

Fuel

results

Gain

earlier,

boards

These,

reasons.

and the

to better

to achieve

to support

experimental

The authors

it down-sizes

the preferred

for operation

environmental

characteristics

It is expected

be necessary

as now defined

ICF fuel because

D-T was proposed

in the next decade.

for a well conducted

study and thoughtful

fusion ICF spacecraft.

are to be commended

Tritium production will

such system analyses.

analysis. substantiate

space fuel and operational

would Data are essential

then, are some issues which ICF must address:

7.0 Fuel and Design Options for Space Fusion Reactors

burns D-T fuel which, for MCF because

drawing gain near 100 by the late 1990’s.

is as stated of safety and space in the the laser of

The concept clearly not system performance VISTA study as the preferred requirements. ignition reactors with the attendant

ICF will current almost 300 meters to scale down the size. the laser reduction of Advanced technology. size reductions the excimer Because exists to down-size

the ICF board to cause This would require the use of to 5 MJ.

To obtain the nigh specific assumed demonstrated, beyond

and clearly a lot of work is essential prohibiting of

There is no known technical size laser designs

however, the laser design for a flight application.

power, a high gain reactor design higher That

require a significant level of 0.1 MJ to the requirement

The readiness without apparently test

the status of gain, at a rate sufficient its consideration.

understanding advancing results to suggest

technology of 5 MJ. The current

to power 100 MJ to 200 MJ.

cannot the key indicator

to accommodate research

be established of viability.

believed capability.

the increased related,

A tremendous currently

is essential, than value

those who have access

from the lasers are

this work is weapons

to be on the order

are on the drawing

to the proponents

is a considerably

in length already,

a large number

and to increase

in laser output

to be between

little incentive

of magnitude

this concept

of 4 orders

is essential

the output.

to proceed

technoloav

gas laser

the bank

according

It is to

increase

impacts.

planned

Start-up

Ignition

today’s

require

reason

to be

lasers,

supply

further

output

power

Laser

7-22

for

The

flight.

Power

deliver

inductor

concern

Electrical

uniformly

Reliability

to reliably

distributed,

of analysis

the reactor

driver energy

during powered

is the capability

power. amount

targeted, (1 mm)

(Refer to Rot90.)

target over a period of days to months

The target pellets must be manufactured

7.0 FuelandDesignOptionsfor SpaceFusionReactors

under consideration concept to determine

an load to a moving, at a repetition as the vehicle

Another accurately very small rate of 30 hertz. proceeds

The high energy missions of electrical considerable intended the propulsion long duration missions ICF as a good candidate

The nature of nuclear reactions in the ICF mode is different from the low pressure MCF, thereby providing some reduction in the fraction of fusion energy emitted as neutrons. The neutron level, nevertheless, is still quite high, causing it to be a significant consideration in vehicle design and operations, particularly in the vicinity of SSF.

Operations unless to name several, must operations, Space Station Freedom or to other environment, effects

on the as a testing due to its size as well as

the concept will not be used flight to the

technology. include: minimum perturbations flight operational

Many or nearly all of ground, system will a consequence

a requires to perform the from the of

are also large consumers is new and its ability

qualification of the neutron and x-ray emissions.

of radiator design technology. capability will not be reached.

in flight must be simplified is a totally

as required with NERVA. concern.

the system components to be possible.

at a high efficiency. While that would not detract

spacecraft, minimum based

and this is expected require in-space

capability rejection power performance

cool down the tritium mass

control procedures required

for on the strength

source for those missions.

of complex of

for space flight control,

The system requires

should However,

system implications

and consequently

in the specific

on the Earth’s

The availability

a substantial

improvement

be verifiable

the specific

are overall

implications

the vehicle

with Earth

Operations

is another

avoidance

Otherwise

capability,

Simplified

Radiators

interface

enabling

function

minimal

Testing

centers

energy

fusion

there

7-23

heat

this

the

ICF

and

thrust

topics

in an

design

studies

plasma

Plasma

on the

concept

analysis

provides

chamber.

approach

speaking,

to fusion.

alternative

to develop

It, therefore,

a technology

characteristics

The exception

aforementioned

but an entirely

will need to be

are to be attained.

is the demonstration

and recombinations,

the most expensive

for their applications.

as that which VISTA

but will not be pursued

from two points. One,

if the quoted efficiencies

to understand such

for space unless NASA elects to undertake

that MCF does not yield the desired results.

7.0 Fuel and Design Options for Space Fusion Reactors

concept, managerially different

uses and the plasma’s kinematics, The plasma

Further warranted fusion program. continue

are a ICF gain which DOE will

There unconfined interaction particularly better understood

is a need space with the magnetic with regard to cooling

This is an important offers not only an entirely technical event One of research which NASA can acquire without monitor goal not high on the DOE priority

The ICF progress experimental least better the technology Hence, of the demonstration or not drivers. Whether depends on the viability NASA alone will have to explore.

the or at is D-3He. is in required for D-3He and light weight system that

The performance since it inherently and the thermal MJ) mass research development. necessary. generation, unacceptable life. Breakthroughs could become

back-up reason is leverage. i.e., funding. We only need to simply is down sizing the mass driver,

power will be short 12.3 year half flight tritium during

but driver energies of sufficiently ICF space

of D-3He must be developed powers

inductive are others. of the generation

for long duration missions in research

radiators in specific mass radiator

has been stated to be good; and, even more importantly,

it will serve as a space of

predictions, fuel to ICF funding

results are stated to match well with theoretical

is certainly simplifies constraints

that high specific required

system mission engineering

of MCF (50 low related

where NASA may have to contribute

into a package Other

than with the MCF machines.

plasma/thrust performance

pellet and plasma

The other major expense

For space the preferred

the higher gain values

An order of magnitude

power and propulsion

formation, thrust

the first wall material

different in the

can be designed.

list, one requiring

is demonstration

here, and that

space funding.

of mechanical

is something

recirculation

applications

the issues

to resolve

conversion

an option.

The other

chambers,

permitting

for solar

targeting,

progress.

problems

improved

attractive

because

of gain,

consists

concept

tritium’s

issues

raised

fusion

7-24

This

The

and

for

The

7.2.3

fusion

7.2.3.1

funding

OTHER

research

program.

Therefore,

CONCEPTS

of Energy’s

is too great

of parameters

CONFINEMENT

the Department

such as these

regime. will

could be explored.

the program funding

by which experiment

There are also others,

for Some other

at present and the

they can only be considered as speculative

examples of non DOE funded concepts follow.

like the Dense Z Pinch, a small LANL program

7.0 FuelandDesignOptionsfor SpaceFusionReactors

remain so until testing has been conducted to validate or invalidate

concept. of ~$300K, which have not even been listed.

stands relative to the tool which a SFP could provide confinement

options individuals to sponsor and the risk too high for capital venture.

The intent of this paper is to indicate where their “maturity” mainline concepts. One valuable management is to make available

concepts have been examined in varying depths, but they are not The following pursued under All of these options have only a very small or nonexistent data base at present and to reach the reactor require substantially more extrapolation

the use of heavy magnets but is In this design, rings are The plasma physically produced at the breach end of the accelerator by a magnetized coaxial plasma gun. These plasma rings are initially accelerated by a breach end magnet and then accelerated to velocities on the order of from capacitors (260 kJ, 120 kV) 1000 to 3000 km/sec by a discharge of current producing J X B forces with the torus’s magnetic field. At the end of the barrel, physical compression of the ring plasma results from a converging section at the gun’s nozzle end. Refer to Fig. 7.13 for a description of the reactor.

axially down the coaxial barrel

the plasma is confined without

INDEPENDENTLY

by a magnetic

ACCELERATOR

coaxial gun.

EXPERIMENT

compressed

ACTIVITY)

FUNDED

(RACE)

(LLNL

RING

7-25

ir_---

1’

nDT

cone

rn -3,

gain

in an

annular

1 026

= 150

burnup,

Bp _ 1 03T

vz ~10_

2x10 -2 m

1-2 m travel for 50%

*,,- Initial CT compression

iL To CT gun, RACE accelerator

Fast CTj E ~8 MJ, v z -106 m/sec

Slow, 13= 1 field-reversed configuration (FRC}

7.0 Fuel and Design Options for Space Fusion Reactors

Slow, high density CT, E ~ 2 MJ same IT, opposite BT

Magnetically guided, annular liquid metal flux conserver (e.g., mercury vaporizes and becomes MHD rankine cycle working fluid)

being funded are The gun is of a 50 hz a indicates on which to device on the order of $10M per year.

The gun is now in operation by internal light weight and simplicity. currently pulse rate. A back of 10 kW/kg conduct The reactor

It requires a hard vacuum for operation. to be capable is believed power

The disadvantages limited very fuel fusion

are that test background. confinement

ignition are key concerns. liquid confinement

Magnetically-guided liquid metal diverges with 10-1 T guide field

the Livermore National (Ham88 funding

Refueling CT’s, if gain >> 100 (or gas)

not be an expensive costing

such as RACE may be used as an alternate

The reactor would experiments,

therefore, the plasma integrity

fired a single shot at a time but

Fig. 7.13. Ring Accelerator Experiment

new concept convergence

is a relatively The stable

Divergent-shaped compensates

torus plasma accelerators

has a under under

to the laser propulsion

the high compression

has been suggested

Compact driver

concept discussed

for space fusion.

to be concerned

as development

Its advantages

and retention

the envelope

of hardware

and Har88).

the plasma

(Fig. 7.13).

~5 X 104 m/s

is a matter

Laboratory,

its specific

reasonably

has been

for wall drag

calculation

to provide

and, of

A solution

in Section

examined,

burn region

conditions

Livermore

proceeds,

research

(Ham88)

although

and no

is desired

Stability

science

(RACE).

scales

fusion

under

level.

7-26

with

wall

2.0.

this

time.

for or

7.2.3.2

ONLY)

convert

Cooling

requires

required

requiring

If proven,

according

propulsion

to readily

conversion

to be low.

It operates

net power,

topography

confinement

is envisioned

to be greater

for generating

fusion energy

and power will

some shielding.

require analysis

it would not work.

and experimentation.

Its linear power

It will burn D-3He, but

for ICF. The means of

PLASMAK_-(CONCEPTUAL

in a vacuum environment.

it would be a very attractive

from any of power but

generation. are anticipated

there could be a great opportunity

a 50 MJ driver which is 10 times

is quite different for a high specific

approach It has the potential

7.0 Fuel and Design Options for Space Fusion Reactors

If the concept reactor to thrust

The efficiency than 40%, an order of magnitude

propulsion proves feasible space. electrical requirements

reason found why in principle soft x-rays are produced, been demonstrated lasers. than that

As part of the fusion reaction, has already than greater larger to spacecraft

This designs. at the present or aeronautical excerpt was taken from a proposal with the written consent

A PLASMAK magnetoplasmoid compressible atmosphere. surrounded protected the surrounding uniqueness external time

Fusion mechanical This surrounding Kernel megawatts released the transparent

the more traditional lacks any test support for either space an its design,

ring is with imparts the the same PMK

simple the PMK. the of in the of is

then can be used to operate generator

vacuum poloidal a Mantle of plasma, which

… fully ionized penetration, pressure

to the concept. vacuum field against

by an insulating and cloaked within

achieved through are used to heat

Mantle and into the gas blanket, which

It provides impurity confinement

in the pressure temperatures

burn are achievable.

on the order energy

The unproven mantel physics

of a super hot magnetized

dense gas (fluid) blanket

from the burning Kernel

is a highly gaseous

at the whole

inductive MHD electric

to outside appearances

ignition densities

is a key controversial

It is the Mantle that

fuel becomes

dense gigawatt

… Consequently,

have been held.

a rapid increase

for this concept.

a multimegawatt

ball of plasma

is accomplished

to the inventor.

plasma while

or a propulsion

plasma which

(PMK) that

high pressure

is suspended

of the owner.

in Fig. 7.14.

are which

The concept

temperatures

gas blanket

is illustrated

To describe

an external

The fusion

in a thick

by natural

techniques

A number

aneutronic

centimeter

per cubic

it consists

fuel with

interfaces

providing

densities

radiation

(Kernel),

Actually,

element

system.

to seal

through

reviews

engine.

plasma

a hot,

which

7-27

heat

field

and

for

:UUM

FIELD

PLASMA

…:!i !.’., MANTLE

Fig. 7.14. PLASMAK.

7.0 Fuel and Design Options for Space Fusion Reactors

upon the ability as in ball and to extract in Kol88.

Its development plasma compress concept

it mechanically, is further described

a pure aneutronic the reactor’s

The Air Force had funded this work.

the energy to perform useful work.

and maintain inject

the charged fuels,

produce 7.15 shows

the use and generation

hinges similarly

to burn fuels to

design principle

Migma involves

Fig. 7.15. MIGMA.

of self-colliding

to generate

lightningmto

Deuteron Beam Path

fusionable

to The

(Mag85).

reaction.

MIGMA

sphere,

7.2.3.3

beams

7-28

Accelerator

Fig.

ion

the

this

can

that

field

ions

This

high

than

ions.

must

beam

hand,

limits.

which

rather

driven

power

entails

space.

7.2.3.4

(MICF)

directly

system

inverse

particle

specific

a small

multiple

concept

reaction

surface.

involves

features

produce

head-on

FUSION

intersect

provided

systems,

objective

collisions

magnetic

approach

concept’s

combines

by virtue

collisions.

inherently

producing

efficiency.

INERTIAL

for space

low level

generation

application

maintained

reasonable

to provide

to insulate

CONCEPT)

CONFINED

surrounding

recirculation

recirculating

the plasma

(Maxwellian)

INSULATED

the directed

to rely upon

is to produce

This approach

The advantage

The coated

at a sufficiently

MAGNETICALLY

It has a directed

from the plasma

the ICF technique

has high potential

of MCF and ICF.

can be held within

(HASEGAWA/KAMMASH

The the center

orbits which of

of on the inside

target On the other

is the concentration of

of high energy within statistical

7.0 Fuel and Design Options for Space Fusion Reactors

a hole in the sphere than

higher than is via the metallic

Insulated Inertial Confined Fusion (MICF).

where ICF configuration.

provides the ICF due to a

in gas as in wall,

metal wall the case

Fig. 7.16. Magnetically

impinging to create

upon the inner wall

from the adjacent

A laser energy

is accomplished

an expansion

for propulsive

is 3 MJ and

of a spherical

The plasma

and thermal

subsequently

the plasma.

is contained

(Fig. 7.16).

the plasma

adiabatically

a magnetic

containment

pellet wall

this MICF

the speed

uses D-T

generated

discussed

constraint

of sound

from its

magnetic

thermally

Because

chamber

structure

is much

expands

isolation

exhaust

scheme

through

Plasma

plasma

earlier,

nozzle

longer

thrust.

burns

input

laser

field.

7-29

is a

The

and

into

the

LASER

AND

review

7.2.3.5

DIPOLE

completion

MAGNETIC

have come

of confinement

inertial-electrostatic

Inertial-electrostatic

NEW INTIATIVES:

INERTIAL-ELECTROSTATIC

The Magnetic using

this activity’s to the forefront.

Subsequent to the two new approaches

7.0 FuelandDesignOptionsfor SpaceFusionReactors

single unit, this concept has some inherently attractive features. Refer to Has86, Kam87, and Kam88.

This concept is new and has not received close scrutiny. One concern is whether it will work since as the plasma builds up the laser cut off density is exceeded. The authors of the reference document believe this concern will be abated by the use of an alternate laser which is transparent to the plasma build- up. The Japanese are funding the MICF concept.

of magnetohydrodynamically energetic

ions are confined by Fig

to as HEPS of

magnetic the (Figs.

Energetic is illustrated

program, by DARPA.

It polyhedral

to form a negative

approach beam

on the magnetic

design. spherical

is a new concept

(Bus91) being

1 and 2, Bus91).

ion confinement.”

electron-generated

(High the

confinement

is capable

to contain

to confine

is “based

electrons.

energetic

electrons

spherical

potential

System)

colliding

concept

options,

referred

injected

physics

Energy

funded

by b

Power

quasi-

stable

fusion

stable

7.17a

fields

MHD

uses

7-30

well.

This

The

well

and

that

use

are

..,

”’”

”_

,_.

t,..

.*.,

*lq

”,..

;. o

. _.

:l;_”*

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.:.

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7.0

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for Space

: _ ii ,., o :..o..’,...’.’,’_

.-” ?y..-..

:::::,./.’:..’.,.j:::

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Fusion Reactors

.. *..: ”.:.’:’,,,:,._.,D.

.,, r,”: ”,:""-’.’"". . I.tt*:

_” REACTION

Fuel and Design Options

…v :’.:.’.,’.’,” ”-. …-.,.’.::...*;.,’:’_..-.

ELECTRIC POTENTIAL WELL

VOLTAGE

)...o_i. PRODUCTS’.-’ ."" .-,…-.f-,..::. ”.”.

”/,,,./L._ \ //,,_-‘_Y’,,\

inot well and remain

ION SOURCE

they make fusion

MAGNETIC FIELD LINES

Inertial-electrostatic

MAGNET FIELD

radial oscillations

ELECTRONGuN

keV (TYPICAL)

and ions fall

of polyhedral

ELECTRONS

by energetic

ion fuels_)in

DENSITY _

confinement:

Fig. 7.17a.

Fig. 7.17b.

into cusps

INJECTED

__*.t-.t(

reactions

magnetic

spherical

( ((‘w,

negative

potential

injection

trapping

electron

C O,‘L’S

”-----’_-)

positive

reacted

electric

7-31

formed

(_)until

” ”

__k,_.

(_) _

fields

deep

traps

-200

_----

until

well

(_)

”_\

(_.

)

the

that

and

The

was

May

This

A.D.

offer

work

other

“First

since

taken

which

fields;

fusion

NASA

above

Teller,

27-31,

reader

seems

all of

should

means

USSR,

pursue

electric

greater

1920’s.

entitled

physics

energy.

MIGMA

achieve

desiring

concept.

Moscow,

complex,

plasmas,

becomes

approach

Sakharov

treatment

“directed”

a “purely

employed

to earlier

a specific

a chance

presented

approach;

statistical”

and was

concluded

propulsion

suggested

The This

Hasegawa

application

by nearly

performed.

Maxwellian

is referred

is directed

to achieve

of success

of perhaps

Conference

is a non-

commenced

confinement

International

With some

of plasmas,

they would

this nature.

to a space

in the early

to magnetic

is a concept

The authors

is interesting

on Physics,”

is an option

understanding

the historical

is a “focused”

and intuitively

of electrostatic

non-Maxwellian

the reference.

with Langmuir

and Santarius

ICF is another

Dipole.” Fowler,

in this document

new development

“Fusion by Drs.

Maxwellian cites

reference work which

a system of suggested

in a Magnetic Glass,

7.0 Fuel and Design Options for Space Fusion Reactors

the closed magnetic Heat diffusing

in Fig. 7.19 Coils A, A’, and B (the stabilizer)

configuration, Coil C (the dipole)

dipole of order 50 MA,

lines of the dipole open up beyond

and its higher the toroidal

in design to 10 kW/kg.

in Fig. 7.20, will be discussed

As a plasma shown

onto the open lines provides

simplicity, the tokamak

we choose carries

(field null). in the form

provide at a stable

an X-point thrust

in Fig. 7.18 but without

has other complications

gravity or acceleration,

the simple magnetic

exists confined

the coil, as shown

and the description

because power.

Namely, whereas

ring to carry the

is also a “dipole,”

specific plasma

of a magnetically

the magnetically

of 1 kW/kg with

the complication

beam is similar

is well described

as the “divertor,”

a large current,

about weaker

beam injectors

ion beam that

as that shown

to the neutral

in an annulus

The stabilizer

and provides

this, sketched

of converting

of a material

to a directed

the possibility

less suitable

PROPULSION

the tokamak

This means

in Fig. 7.18.

Topologically

configuration

the divertor,

The concept

improvements

is converted

the metallic

now being

confinement

that appear

arrangement

the specific

in principle

applications.

the dipole

the D-3He

extensively

the dipole

the more

its greater

the power

accelerated

the same

accomplish

to neutral

REACTOR

tokamaks.

the coils.

producing

for space

especially

has been

field that

in Section

increasing

reference.

However,

to create

to make

in Tel91,

SCHEME

here for

extracted

(poloidal)

confines

whereby

tokamak

to heat

levitates

between

position

is rigid,

current.

internal

by the

studied

chosen

plasma

current

carried

neutral

carries

energy

internal

in that

against

serves

(Tel91)

strong

rocket.

dipole

atoms

power

ready

as it

used

have

over

7-32

also

field

was

The

that

ring

the

III.

II.

DIPOLE PROPERTIES

7.0 Fueland DesignOptionsfor SpaceFusionReactors

II.A. The dipole configuration has recently received renewed attention, as a candidate D-3H3 reactor (4.5). As noted in these references, according to the dipole exhibits theory, supported by planetary and space observations, the remarkable magnethydrodynamic (MHD) stability up to local values of pressure parameter 13exceeding unity.

causes violent instability that must be overcome by a much stronger toroidal field supplied by large coils interlinking the toroidal plasma. This has the virtue of creating high-shear closed magnetic flux surfaces to confine the hot core plasma. However, for space applications, there is the major disadvantage that a divertor coil to open up the flux surfaces to allow propellant to escape must compete with the strong toroidal field, whereas in the dipole the divertor field need only compete with the weak outer regions of the poloidal field of the dipole coil. Thus, though the tokamak has a divertor of sorts, it serves only to dump heat on the interior walls, inside the toroidal coil structure, and does not provide an escape path for propellant. In addition, the simpler dipole is expected to be much less massive than a tokamak of comparable power and therefore to produce greater specific power.

Dipole Reactor Propulsion Scheme.

Synchrotron reflector

Propellant inJector

Stabilizer

Fig. 7.18.

surface

Neutral

X-point

Dipole

7-33

Flux

izer

[]

]

I_’_

—3—

“1-

7.0

Co II

_o- O’J

Radius

for Space

Fig. 7.19.

Dense plasma

Fusion Reactors

Fuel and Design Options

Detail of propellant

feed and thruster.

view of magnetic

Weak (s,ablllzer)

cross-sectional

flux surfaces

and plasma.

Fig. 7.20.

Expanded

Input IVl

Propellant

_X-Poln,

7-34

(thrust)

[m)

field

”

not

the

not

7.3

not

can

and

The

was

also

later

least

cited

were

have

used

cross

Many

which

listing

There

Mil76,

fusion

Tel85,

herein

These

others

details

Where

Gla60,

tested.

I have

7.2.3.6

USING

include

various

Che74,

Journal

in this

of key

SPACE

Nuclear

A good

included

evolved,

intended

as well

overview

Society’s

concepts

included.

in many

proposed

ENERGY

American

reference

document

Additional

presented

the early

be found

READING

on some

of many

judgments

of Fusion

individuals

FURTHER

in any of

from the

led up to

of devices

to provide

the earlier

documents.

approaches

experiments

Technology.

confinement

fundamental

experiments,

be obtained

and Rot86.

be obtained

or proposed.

a discussion

configurations

EVALUATION

are still other

an all-inclusion

This document

and description

a representation

section of

in a non technical

the more matured

establish sufficient

book may found

at approaches.

from Bro82. texts.

fusion and updated

a representative to include

7.0 Fuel and Design Options for Space Fusion Reactors

be considered consideration

of a fusion Several

development electrical

as potential further

involved with space

why NASA should

to their applicability

and for experimental

of 7.2 can

from the mainline

and concepts

new and different

and is part of

engine reactor

experimentation.

and terrestrial

are considered

APPLICATIONS

rocket the of

PROPULSION:

for application

CONVERSION

consequently

will produce

configuration

configurations

and interest

experimental

is a matter

applications.

CONCEPTS

the space

and other

experiment

phenomena

applications

approaches

by testing,

unexpected

companies.

from that

particularly,

a situation

secondarily

new and

for space

in Section

CURRENT

program’s

technology

discusses

conversion

Comments

the DOE

for space

problems.

generation

uncovered

developed

propulsion

programs

sensitive,

applicable

programs.

discussed

program’s

concepts

remaining

analysis,

to space

ENERGY

proposed

important

rationale

in fusion

preferred

tokamak

different

as well.

generate

objective

chemical

electrical

following

ENGINE

designs

FUSION

systems

reactors

diverge

become

testing,

relative

leading

primary

Testing

testing.

options

design

receive

section

current

energy

in the

power.

fusion

should

design

In the

results

where

power

space

fusion

space

fusion

space

since,

unlike

which

many

study

utility

been

7.3.1

differ

is in

have

used

This

7-35

best

very

test

The

and

part

The

and

this

the

our

are

not

the

will

for

that

point

then,

(MCF)

exhibit

7.3.1.1

source.

concept

program

FUSION

by which

and meet

The most

the space

conversion.

CONFINED

combination

commenced

confinement

the funding

is the initial

As mentioned,

fuel of choice

low _ reactors;

MAGNETICALLY

for fusion energy

look as a starting

the MCF reactors

question, fuel

is deuterium-helium-3.

and they consequently

is to decide the design

the system performance

nature of a reactor which can

the direction where the space

have received to theory,

NASA to meet anticipated mission

been low pressure, power characteristics.

fusion as an energy in 1950.

7.0 Fuel and Design Options for Space Fusion Reactors

important burn (Section implies designs,

The DOE MCF systems the most attention

and therefore and testing. With some exceptions,

are provided with the goal of defining should

6.0) enabling higher magnetic and good plasma stability

Magnetic produce controlled Sherwood, vast majority experimentation, basically specific

efforts were made to The first major program, Project the design, have low

terrestrial use: generally must produce one realizes higher, current mainline MCF designs. it’s magnetic field load carrying One advantage eliminating accommodate

in the are plus its neutron shield. vacuum “tank,” to

which provided typically is funding was not made available.

There plants, preempted request positive terrestrial Unfortunately,

the clear of a possible NASA program (FRC).

power than the at Some very the for sensitive.

structure is the readily available and

it suitability Section 8.0 examines

by a hard performance the DOE on high power density

Details for space follow. Considerable

reductions two major mass components

This study’s initial for space Currently

in mind that space power value of 1 kW/kg,

weight The reactor’s and supporting

and linear. Keeping a minimum specific

of suggestions program

power is more a profit

(Dav85). the need, even

design vacuum facility.

the commercial issue

reactor designs preferably

specific the motivation

is interest too, although

in an early state of development,

requirements. radiation,

low cyclotron temperatures.

is placed on the reactor’s

Two basic MCF design

This low mass

A study was performed

albeit at a very modest

all of the MCF designs

is the Field Reversed

of terrestrial

choice for proceeding

with the development

is being terminated

the most attention

in greater depth.

after considering

fusion systems

and discussion

on the various

level, work or

are necessary

have received

the attendant

were which

the preferred

configurations

Configuration

requirement.

requirement

parameters

the space

considered

conclusion

supported

significant

strengths,

in higher

emphasis

a “clean”

at higher

operation

in 1991.

designs’

reactors

toroidal

reactor

design

is that

fusion

rather

mass

7-36

field

that

not

for

the

7.3)

was

The

field

have

force

some

stems

power

(FRO)

thrust.

toroid,

exists.

space

nature

FIELD

steady

levels.

current

version

funding

specific

actually

Several

poloidal

density,

designs

features

appears

program

capable

potential

because

meeting

although

7.3.1.1.1

systems.

Although

of direct

required

attractive

presently

magnetic

terrestrial

potentially

no space

a number

A toroidal

limitations.

terminated

topological

the linear

conjunction

a concept

Technology

This work

and linear

good state

at Spectra

confinement

REVERSED

FRC (Fig.

is classified

and overall

in operation

of methods.

lines would

the external

is scheduled

It combines

is considered

this machine

be conducive

to the space

as a compact

of Washington

As mentioned,

of ignition

and a reversed

of both toroidal

to be applicable

The confinement

high design.

CONFIGURATION

the attractiveness

at Los in

to the production

to be shut down

two end magnets

with the University

been in 1990

scheme, compact

plasma operation,

performed. and

from its high 13(<90%),

for is provided

field which may be initiated

FRC reactor Alamos

along is by quickly

The machine other

7.0 Fuel and Design Options for Space Fusion Reactors

100 keV 107 meters/sec 106- 103 seconds

Ion Temperature Exit Velocity Specific

TABLE 7-5. FRC Predicted Performance.

Fusion Power Plasma Volume

Ion gyroradius Plasma radius

accomplished plasma

use The attractive

energy multiplication.

possibility with

of because

The (Cha89):

0.5 GW 80 m3

and by increasing

0.01 m 1.5 m

the surrounding

from the wall.

Specific Power

by a magnetic

and sustained

the magnetic

the confining

at one end,

is presented

this concept

for a fusion

compressing

the plasma

performance

is produced

The fusion

by a field

entrapment

imbalance.

0-0.8 kg/s

0.4-50 kN

from the

Propellant

10 kW/kg

physically

in Table

produces

predicted

magnetic

providing

attractive

the fuel

to the

products

to heat

a rapid

ramping

remains

addition

Impulse

plasma

directly

reactor

current

engine

makes

nozzle

Thrust

away

field.

work

lines

7.3).

7-37

(Fig.

heat

One

axis

and

7-5

the

for

that

The

laser

have

been

linear

prime

would

fusion

driven

is the

mirror,

shown

supply

factors

earlier,

in-flight

leading

and it

tandem

reactor.

reactor,

it could

device,

designs

suitable

powers.

difficulty

is likely

systems

Perhaps

(San88).

7.3.1.1.3

7.3.1.1.2

MIRROR

tokamak

terrestrial

achieving

TANDEM

designed,

terrestrial

propulsion

for over

for space

controlled

considered

TOKAMAK

continuation

view point

The current

in Fig. 7.6,

high specific

The mainline

As discussed

such designs

be considered

of 10 -4 kW/kg.

ablation 2.0.

warrants upon

to in depth

power has not

fusion experimental

electrical power

power discussed

the best understood

for propulsion

capabilities conversion

further preliminary

design for a lunar

is designed generation.

produce in Appendix

the required power

consideration. conceptual

or B and Section

has a specific based surface

to demonstrate A tokamak

that by the University

7.0 FuelandDesignOptionsfor SpaceFusionReactors

ion beams flux, was studied

injection, along magnetic

to electrical is

and, effort would

some be required

That program assumes

conversion the

greater of specific

under burn conditions

direct developing

by NASA subsequent

can be demonstrated.

hydrogen Research

direct propellant

used to accelerate

is being performed

the one selected.

specific a wide

a tandem mirror

at NASA Lewis

to the initiation

of tandem

or, alternatively,

the Spheromak

and theoretical

thrust option,

of this study.

TO THRUST

in the 1960’s

one mainline

CONVERSION

that plasma

the tokamak

investigation

of Wisconsin

a substantial

a moderate

only a very

consideration

confinement

as potential

the means

development

high betas.

experiments.

experimental

into thrust

is available,

to continue

experiments

and FRC.

significantly

of plasma

to develop

lags other

COMPACT

for space.

to include

conversion

constraints

the DOE

TOROIDS

in 1986;

is based

1 kW/kg

PLASMA

important

terrestrial

tube of

presently

Compact

analysis

relatively

(Eng66).

7.3.1.1.4

7.3.1.1.5

occurred

research

by MIT.

although

it would

initiated

concept.

compact

program

decision

difficulty

Plasma

Another

impulse

prudent

tandem

remain,

activity,

funding

energy

options

A key

include

energy

nozzle

power.

toroids

Center

placed

exhibit

values

matter

throat

power

fusion

space

mirror

range

exists

thrust

being

direct

since

small

allow

Their

upon

base

point

That

7-38

that,

data

than

they

was

high

only

and

with

The

and

into

this

are

the

for

its

the

and

Two

7.3.2

tasks

much

effect

major

fusion

space

transit

needs

during

These

losses

exiting

Clearly

reports

nozzle.

greater

plasma

through

Another

analysis

illustrate

POWER

separate

program.

are cited

emphasis.

application

technology

importance

of plasma

the nozzle.

of a space

ELECTRICAL

7.0 FuelandDesignOptionsfor SpaceFusionReactors

The Air Force recently completed a study concerning the “Characterization of (Ger89) A wide variety of Plasma Flow Through Magnetic nozzles.” temperatures of plasmas was investigated ranging from 1 ev to 100 ev with some consideration given to temperatures as high as 1 keV. The report’s abstract concludes with the statement that ”… the use of plasmas for space vehicle propulsion is a natural and interesting application for plasmas that well deserves further study.” Several points are raised pointing to the importance of further work on this subject. There is a question raised concerning the viability of plasma propulsion at high densities, where n = 1017 to 1018 cm -3, due to is the effects radiation

electrical of converting use for electrical

generated purpose direct

power. it power

application the at

life support, materials

voltages end.

into electrons

as an ion engine

to grids system

data transmissions,

from one end of

high DC voltage

by the and

directly recover

to a propulsive

to accomplish

in Fig. 7.21.

CONVERTER

schematically

is converted

experiments,

The kinetic

the reactor

as science

applications

processing,

of plasma

be made

operations

for or

Electrical

identified

available

opposite

particles

DIRECT

the for

of bias

conceot

at one

Design

7.3.2.1

energy

space-

shown

devise

power

to is

been

have

such

flight

7-39

ions

The

end

can

etc.

for

”_

a..

the

out

that

al.,_

grids

v 3

pointed

Cooling

(Mi176).

—.-b_.

is required

/-------_

COLLECTOR

”_…-.---

…,..,,,. _.

ELECTRON REFLECTION

Fig. 7.21. Direct Converter

S. TS

coo.eo

GROUNDREFERENCEGRID

SECONDARY-ELECTRON

/” SUPPRESSION GRIDS (

7.0 FuelandDesignOptionsfor SpaceFusionReactors

at up to 100 kV with a net efficiency High

Livermore of 48% (Bar81). voltage

conversion performance efficiencies

for system addressed

techniques including only

converters (LLNL) attained

high a fusion (Ku187).

is to increase attendant

advantage are illustrated

for a space given.

“ultrahigh components.”

is illustrated Relative

system inefficiencies

conversion thermal

the direct to avoid

operational Tentative

handling interactions

test a concern

National The best

conversion inherent

will on direct

of mass minimization

for a 1000 MWe

issues solutions

other (San88).

voltages reactor

(above Testing

by the University

Perkins, almost

system produces

require power

cut was made

voltage using

due to heating

it perfect

the Air Force

APPLICATIONS

one magnetic

preconceptional

high voltages,

by Fig. 2.53.

power with

at addressing

on the order

of Wisconsin

is concluded

accomplished

The mass

at Lawrence

environment,

In a recent

in a space

conceptually

researchers.

the D-3He

of with

preference.

Status

efficiencies

importance

efficiencies

breakdown

has been

conversion

from the

throughout

Laboratory

as shown

of 1 MV.

conducted

expressed

performed

that the

approach

It should

ion flux.

in more

possible,

objective

systems.

products

Charged

exhaust,

(Bar77).

reaction

by Dr.

another

SPACE

by the

Section

(Per88)

by the

plasma

particle

SOAR.

reactor

7.3.2.2

reason

A first

mating

+1.5%

recent

power

fusion

space

fusion

times,

paper

found

these

direct

make

result

study

60%)

been

have

were

Only

That

7-40

86.5

high

also

was

The

and

2.0.

and

this

the

for

showed

applications.

fusion systems

reactor reactor

for space could

of electricity of

in Fig. 7.22 which compares

The study power orbited

7.0 Fuel and Design Options for Space Fusion Reactors

results

of approximately (Ku187). The order both a

a specific deliver for every kilogram of material is illustrated

fusion power plant that a D-3He fuel kilowatts of magnitude 250 MW and 1000 MW reactor with the Shuttle Orbiter.

The systems were designed made of the highly efficient scheme optimum performance tandem mirror design. While this particular the NASA space missions without modifications, considered it gives planning fusion power application,

Fig. 7.22. Order of magnitude of fusion systems comparing both a 250 MW and 1000 MW reactor with the Shuttle Orbiter.

The preferred concepts been given a through from this other options.

for space now under way outside of NASA and shows the feasibility

shown by their calculations design would

those missions and of

to yield that power conversion

Use was The is the to

review is the Field Reversed Configuration.

for 600 seconds. of energy

not be applicable for

at the advanced

proof application.

based upon preliminary

is deuterium-helium-3.

The one preferred

for demonstrating

an understanding

are likely to be

and experiments

design have

to electricity.

of principle.

calculations.

confinement

electrostatic

SUMMARY

the space

are many

for space

evaluation

thinking

herein,

There

None

least

7-41

fuel

7.4

for

This

data

fusion

reactor

section

SPACE

FUSION

including

objective

examines

fulfillment.

particularly

in Section

conversion

this study

of offering

It presents

application,

the means

the energy

REACTORS

In particular

extrapolation

high energy

the chances

requirements,

as presented

their fusion

8.0 STATUS

to the critical

data base to

the status of

relative reactor

those missions,

OF POTENTIAL

required those

4.0 and evaluates

the implementation

status. presented

has been to examine

AND PERFORMANCE

with regard to meeting

approaches, those

of it examines

and technical concepts

in Section 7.0 having a sufficient

and exploration missions, mission

and the planning to achieve

space mission requirements

into the space reactor having the greatest

The major science NASA for their

energy missions merits, confinement

regime potential parameters a successful

the concept the reactor designs relative

perform a reasonable and emphasizes for space. discussed

space the program impact on for high

Great progress has been made on a technology that can be considered as one of mankind’s

results the progress which has been made in the upon some

The perception frequently encountered concern fusion

long period without more from a lack of understanding program rather terrestrial

who are not acquainted because

technology with it has been researched

technical challenges in the physical sciences.

indicated a that for a

There are a number of key parameters

is not a viable source of energy

during this study, however,

of than being

yardsticks. (Fig. 8.1).

when using progress

physics or technical

to be considered

That perception

BACKGROUND

TERRESTRIAL

energy output

net, controlled

the equivalent

by individuals

GENERAL

system and

2.0 and 6.0.

the ratio of

fundamental

the vehicle

PROGRAM

per energy

in Sections

producing

Consider

STATUS

greatest

energy.

based

fusion

issue.

input

8-1

8.1

10_3”

T-3

JET

PLT

10-8

10-5

10°=

1970

10-7-

10 -2.

10 -1.

n_ 10-4.

LUlLU 10 -6.

ALCATOR-A

ALCATOR-C

DOUBLET-Ill

8.0 Status of Potential Space Fusion Reactors

successful with the achievement

equivalent energy output per energy input

progress as expressed by the ratio of

by the Wright too.

being solved. breakeven

the projection first

demonstration of

to Fig. 8.1 for a description

Fig. 8.1. Plasma experimental

demonstrated expected,

travel once development

will most technologies.

development first

technical demonstration!

(San88 - updated to 1990).

comparable indeed

this study, years.

had been demonstrated

from the the

materials. strides.

will be demonstrated

greater Consider

brothers. Look

and then consider

is true with most

The reaction.

initially not be

from the plasma

of several

the first manned

be unsuccessful

The magnitude

the Almost

the technology

and the work

than should

great would

underestimated.

semiconducting

of net power

is to produce

a net energy

of magnitude

that holds

advancements

demonstrated,

demonstration

the progress

by a longer

accomplished

by hundreds

the difficulty

psychological

likely make

even more

D-T energy

be of even

improvement

confinement

was made

importance.

significance

technology.

in a rapid

Confidence

anticipated

researcher

electronics

production

expansion

equivalent

the early

The the

of Bell’s

an event

telephone

producing

remaining

7 orders

controlled

illustrates

discovery

preceded

it should

terrestrial

problems

expected

of years

technical

originally

following

because

anomaly

difficulty

is high

failures,

of any

In fact,

Fusion,

1950’s.

in the

difficult

energy

to the

in the

Fusion

During

output

period

phase

YEAR

fusion

within

be a

in air

Refer

flight,

since

great

1980

1990

been

input

have

point

once

even

after

than

ratio

task

was

with

The

that

late

first

8-2

are

the

will

8.2

in to

(JET)

Thus,

Torus

fusion

remains

is “what

FUSION

attention

technical

program.

too early

DESIGNS

is unique,

propulsion

by NASA.

REACTOR

to become

the pursuit

MATURITY,

RESEARCH

the preferred

The application

at is not

COMPARATIVE

time appropriate

is the work that

viable for space?”

to be accomplished

progress. England

to be demonstrated,

To obtain a measure

fusion issues of

status let us then examine

The Joint has reached

of a space fusion development

European a gain of 0.8.

by DOE and the need in NASA for high energy

is confinement to maintain is still

8.0 Statusof PotentialSpaceFusionReactors

program. requiring very directed

the Culham Laboratory for NASA

concept(s) accomplishments of

in this section the critical potential.

and the performance have yet the plasma

commence achieved make the present investments made by the terrestrial to space missions

The progress systems to seize upon the benefits of the very modest energy

For NASA the key question for fusion energy technology of fundamental of which capability operation the SOAR, a linear direct converter Other others.

long issues reactor design, were: plasma physics,

steady for examined high voltage (San88). those issues plus

A number the most apparent The yield.

recently fueling, low radioactivity

Major areas in need of to be necessary

to produce under of critical

mass flow rate thrust augmentation,

and designs would have some of

to support a space flight capability

fields for space reactor designs,

a net energy duration

low specific mass magnets

design, and the operational

under net power operation,

by this study, and shown

space fuel conservation

flight control systems

the flight operational

plasma confinement

space start/restart
the development

of plasma energy

plasma stability

of high magnetic

some uncovered

and light weight

ash removal,

in the exhaust

to controllable

further away.

thrust power,

the efficient

configurations

investigation,

recirculation

conversion

impact of

structures,

Examples

efficient
minimal
reactor

a stable

plasma.

regime,

plasma

reactor

power,

under

state

(J3),

are:

8-3

2.0,

fusion

nature

(TPA),

toward

reactor

divided

plasma

entitled

interest

aspects

a the

program

the first

Because

in which

terrestrial

examined.

50 fusion

has been

on reactor

researchers

to examine

and Dea85.

and systems

ICF prevents

the classified

topic of great

Science Group

plans to develop

Planning were

study of over

and ICF (inertial).

power. each of

The key publications

Activity” assembled

focus approaches

the TPA are: Bak87, Cal86,

heavily upon a recent Department

8.0 Status of Potential Space Fusion Reactors

this study analyzed MCF in greater depth.

plasma in the There are 4.0, MCF

The TPA Plasma seven main categories,

in this section depends the “Technical

the development research for

fusion given in Table 8-1 (Cal86).

(magnetic) further discussion was accomplished

The MCF information of Energy committee

The major confinement establishment two approaches

physics, technology, The TPA produced the concepts Abd85,

the terrestrial which of the conclusions plasma

is clearly that are to be drawn from this study. in Section as discussed confinement

in this report and since a study termed “VISTA,” Section using ICF,

The term “Macroscopic held by the magnetic maximum plasma achieve, are: disruptions,

is since it deals with the can

classes of the regime where exceeds produced

scheme in this category magnetic

TABLE 8-1. TPA Plasma Science Group Plasma Physics Issues.

issues were associated with the next generation

related to research Issues,”

field. pressure it determines

the plasma the input power.

of experiments the fusion

Macroscopic Equilibrium and Dynamics

the reactor’s magnetic

Equilibrium and Dynamics”

Five classes major

confinement included

refers to how the plasma

Burn Control and Ash Removal

that any given magnetic

issues were considered

J]. Issues equilibria,

of category

Burning Plasma Issues:

plasma kinematics

when magnetically

Confinement Systems

Alpha Particle Effects

It is an important

that forming

as “Confinement

and in general,

and power

to be primarily

in the two

is “burning,”

Particle-Plasma

Wave-Plasma

minimizing

is, where

sustaining

Interactions

confined.

Composite

Systems

Transport

physics

subject

shown

issues

Issues:

Issues

other

while

and

that

into

8-4

is,

This

refer

refers

noise.

losses

neutral

current

density

Issues”

stability

physics,

of short

including

sensitivity,

of plasma

option for

to heating

to achieve

“Transport,”

In addition,

Interactions”

the plasma

the plasma’s

is, degradation

plasma-material

into the Lawson

to the interactions

due to amplification

FRC’S, RFP’s, etc.

the plasma with its

on the velocity-space

field lines or parallel

parameter, plasma

to plasma confinement

refers gas, atomic

raising The reactor’s

deals with the heat and particle

from a stable to

for burning. for the operation

Transport and confinement

and neutral particle beams when used.

8.0 Status of Potential Space Fusion Reactors

to the temperature in Table 8-5,

that are either normal of both.

“Particle-Plasma environment, impurity

is an important needed is important

As shown later, a value of II’rE> 3X1020 sec/m3 at an ion temperature

to the magnetic figures time necessary

for externally energy drive, of current driven machines

“Wave-Plasma that scale, wavelength powered waves. level presented like tokamaks,

The term, plasma, them or combinations IIz E, the energy burning. of 10 keV is required to burn D-T.

The major issues, burning has been demonstrated.

“Composite aforementioned balanced encompasses the pulse length.

equilibrium, heating effects, and effects of hot alphas.

fuel cycle would Based upon configurations, three categories:

the issues must be It and

to the interrelationships All of issues. perspective

“Alpha products on plasma particle containment,

deal with ignited the plasma of removal.

to alpha of understanding classified

“Burn Control steady-state removal without

issue dominates. the plasma profiles,

and Ash Removal”

control behavior

in their approach and alpha particle

from a systems optimization

those as no single

The TPA study was primarily

and tradeoffs plasma

aimed at the D-T fuel cycle.

Issues” of processes

effects. the for into

particularly of plasmas.

plasmas constituents

science trade of

which to address

the reactor configuration,

heating and transport,

Science Committee

reaction alpha

(1) well-developed

tritium or helium-3

with consideration

science to the

the TPA Plasma

once breakeven

to the plasma

are two major

(2) moderately

(3) developing

proton of

a judgment

the effects

are unique

of charged

base, and

in addition

the D-3He

Issues for

deal with

knowledge

developed

surfaces,

including

categories

Spheromak

confinement

Table fusion

the magnetic

Tandem Mirror

Dense Z Pinch

(TPA) magnetic

LESS DEVELOPED

WELL DEVELOPED

Advanced Tokamak

Elmo Bumpy Square

Reversed Field Pinch

8-3 below summarizes

the TPA’s program’s

classification status.

MODERATELY DEVELOPED

Field Reversed Configuration

TABLE 8-2. classification

8-2 summarizes experiment

8.0 Status of Potential Space Fusion Reactors

Technical of reactor knowledge base.

TABLE 8-3. concepts examined in the technical planning activity.

Transport Wave- Plasma Interactions

Macroscopic Equilibrium and Dynamics

Tokamak Tandem Mirror Good

with be emphasized

Particle Plasma Interactions

as in the most

by each low assigned.

parametric and D-3He,

understanding good,

interpretation position

8-4 as are ICF parameters.

embodiment. fuel

reflects necessarily

level of understanding

Composite Issues

FRC EBT/EBS

study represent

values projected

Required D-T

of plasma physics

is its performance

a value that

Medium Medium

Low Medium

of very table

for It must

its burning

the TPA report

good, medium,

reactor of

to the issues

to Table A-l,

of a concept

with respect

Good Good

A judgment

confinement

experiments

the official

Spheromak

the status

the TPA’s

Very good

issues for

the DOE.

Subjective

Stellarator

applicable

Low Fair

presented

in Table

evaluated

regarding

Appendix

achieved

in Table

measure

contents

activity’s

required

Medium

options,

concept

Another

Reactor

respect

results,

values,

issues,

it may

during

made

Good

Refer

been

MCF

level

RFP

TPA

Low

with

8-1.

and

has

two

this

are

8-6

the

not

the

for

8-4.

(keV)

space

fusion

Space

D-3He

TABLE

plasma

6x102s

6x1021

6x1014

3x1013

1.4x109

4.8x107

6x10 TM

reactors.

2.4x1015

2.4x1027

at [3= 1

Parameter

R/A ,=3.3)

8.0 Status

of Potential

for generic

at 13= 0.06

torus driver)

development

requirements

Characteristic

MICF (compact

ICF (Laser driver)

Fusion Reactors

MCF (generic torus,

(with DT spark plug)

Burn Temp., TL (keV)

Magnetic Field, B, (T)

Fuel Ignition Temp., Tign,

Plasma pressure, p, (bar)

Fuel Ion density, ni,(cm -3)

it is very much less

MICF is included developed.

in the table; but, a very recent approach,

the ICF an ICF gain of 1,500,

Table 8-5 (a), important most programs’ Section 2.0.

Gfom = (Gideal _c)fc_la, charged MJ/electrical MJ

parameters physics The VISTA study

Assumes an initial DT plasma re-fueled with D-3He.

and the test of

Electrical input, Eign/(TIcTla), (MJ)

Plasma ignition energy, Eign (MJ)

Energy/fuel confinement ratio

the current MCF

Driver energy, Eign/YIc, (MJ)

Fuel confinement time, “ri,(s)

Coupling efficiency, _1c

(b) summarizes

Plasma radius, a, (cm)

fc = Echarged/Efusion

Fuel burn-up fraction,

1.3x10 “6 5.3x10 “7

Auxiliary efficiency,

experiments.

the status

fc Eign), (MJ)

assumed

achieved

Fusion gain,

(Gideal _a)

ni_iproduct,

plasma

1.6x10 “11

2.2x10 “11

results

7.2xl 0”3

4.8x10 .3

9.8x1015

1.3x1016

3.2x1015

1.3x1015

1.3x1016

(cm”3 s)

3.5x103

1.9x104

energy,

30,400*

20,000”

3x1015

plasma

(Gideal

Useful

output

and

8-7

1680

220*

400*

100”

180”

0.15

0.57

0.45

0.19

0.65

0.15

0.31

0.15

0.10

0.30

0.44

for

300

100

168

111

730

“qa

0.4

0.9

0.4

0.9

0.1

0.5

0.9

0.2

1.4

1.9

1.1

7.3

2.7

0.1

0.6

0.2

0.4

0.5

0.4

NA*

0.05

RFP

FRC

Status

lx1015

3x1017

6x1015

6x1016

2x1016

2x1020

2xl 019

Tokamak

EBT/EBS

St ellarator

Spheromak

Ion n_E, m3/s

Density, cm “3

Time, seconds

Tandem Mirror

NA-not applicable

ICF reactor concept.

Key fusion experiments

TABLE 8-5 (b). Status of

Average 13, %

Plasma Current, MA

Ion Temperature, keV

8.0 Status of Potential Space Fusion Reactors

TABLE 5 (a). MCF achieved parameter status.

parameters, conversion products. plasma without products, then serves to heat made towards meeting the Lawson criteria is shown in Fig. 8.2 (San89).

such as 33% energy by fusion from the fusion and their energy and status

breakeven value of condition is the point at which the total the reactor would these

Lawson made certain and as typical

at a given temperature if it were converted burning.

The Lawson nt required fusion output, self-sustain

100% efficient reaction of energy

the net electricity Ti. Breakeven

products, to the plasma.

the plasma and any cold fuel

assumptions of heating

although efficiency

input. The progress

by the background

lost charged

ions, are slowed

are immediately

and reinjected,

Energy Input, MJ

an excellent

the plasma

to electricity

(nt) defines

a transfer

Neutrons,

provides

estimate

Gain, Q

criteria

10 “10

This

The

i.e.,

first

0.03

8-8

0.3

I—

”_

‘69

‘86

T-3

0,1

O m

‘86

I000

i0 tl

TFTR

…

Space

IO0

iTFTR

C ‘8_

G) ¢L E

ALCATOR

JET ‘86

8.0 Status

of Potential

,,,,= ,.,,,,_

e89 FRX-C/LSM

Fusion Reactors

I O LSX (FRC)D

J … 1 …

.x.c

l=|lllj I

Achieved 0 - Projected

I t \DT

For achieving of the type that have been examined

over a long burn duration without maintenance.

D-T ignition the confinement

in the tokamak time,

transform into the following

collectively and density

space we require

system safety potential,

achieved possible.

concerning benefits

conclusions tremendous

and ease of energy

6.0 will be designed

into the system or

system parameters

low vehicle mass,

as a consequence

is as aneutronic

for ultra-reliability

traits presented

in this analysis

highly inherent

n’_ (crd 3 sec)

flight missions

a fuel which

high potential

other desired

the advanced

the capability

high specific

to accomplish

high energy

understanding

performance,

of selecting

the required

temperatut:e,

REACTORS

approaching

fundamental

are rapidly

propulsion:

parameters

operational

extraction.

parameters

in Section

to achieve

simplicity,

efficiency,

individually

Many of

important

to space.

of NASA

and that

to make

experiments

reactors,

variable-

to meeting

stability,

be met:

It shows

progress

density,

impulse

FUSION

specific

required

conditions

use of

plasma

ignition.

SPACE

Fig. 8.2.

positive

power,

energy

(Lawson

space

fusion

(SFR)

burning

these

status).

ability

relative

these

good

criteria

limits

Status

burn

have

each

high

fusion

That

they

that

lO t3

tO t6

and

1015

that

key

met

For

five

the

i012

8-9

8.3

the

for

llltJJ

llllll

8.4

FOR

desired

designs

however,

approach

ENERGY

The dipole

on testing of

PROPULSION

CONVERSION

the conclusion

and, of course,

of the characteristics

power will be attained

is the tandem mirror.

as two main experiments

The FRC had been funded

on general as shown in

can only be based on detailed

Technology, $5M annually

that and is tentative.

It is therefore a SFR.

the FRC exhibits possibility

8.0 Status of Potential Space Fusion Reactors

is another. the FRC is based

only by high 13machines. required

about It is not a well developed

the highest exists for achieving (Tel91)

These will exhibit for space. Of all concepts the reactor The second be It should

We can use the FRC as an example reactors for space. (FRX, Fig 8.3) and at Spectra Alamos the DOE at only a level of approximately

High specific the minimum mass and size characteristics shown in Table 8-4, design on which the greatest option stressed, considerations Tables 8-2 and 8-3. A final comparison for space, designs which need to be accomplished, those designs.

ORIGINAL PAGE BLACK AND WHITE PHOTOGRAPH

low level is a very in 1990; in 1991.

This cancelled termination

program was for

later. Technology

fusion at Los by

Bellevue, Washington,

The Los Alamos

at Los Alamos National

as discussed

the Spectra

in 1989-90.

FRX experiment

scheduled

program

Laboratory.

Fig. 8.3.

8-10

paper

Space

further

“Fusion

physics.

(Cha89).

the appeal

The space

the reasons

to space

in this section

the FRC reactor

Nuclear Society’s

for interest

reactor parameters

the data presented

as defined qualitative

Propulsion and Dr. Miley,

theoretical and experimental

entitled by Dr. Chapman

8-6 with a subjective those parameters.

8.0 Statusof PotentialSpaceFusionReactors

below as Table of quoted,

the FRC to meet that from the Eighth American

Let us then develop space. presented capability otherwise obtained poster Configuration” Technology FRC for space.

to by Table 6-1 are the of evaluation It can be assumed, unless the report were of Fusion Topical Meeting Reversed in Fusion

The reactor concept potentially of great benefit and interest unfortunately has a relatively low level of understanding, the consequence of a low program priority. Research maturity, the topic of Section 8.2, is our first interest as we consider the potential of the designs for meeting the space requirements as presented in Section 6.0. While the tokamak is better developed, Table 8-2, and is approaching a breakeven, as shown in Table 8-1, the FRC ion temperature and nt values have a long way to go. Reference the FRC to Table 8-3 will show a low level of understanding reactor’s

a Field published showing

This is the only known reference

details of

8-1 1

later

with

the

X X

FRC

6.1.6

All of

Ignition

the All

Impulse

Unknown

parameters’

6.1.5 Beta

TABLE 8-6.

can be met.

requirements.

6.1.2 Thrust

the parameters

Potential to meet

Does not meet

6.1.1 Specific Power

Comments status

In, and testing to validate that

require thorough analysis, desi

analyses and/or educated guesses.

6.1.3 Specific 6.1.4 Fuel Cycle

status are based upon very preliminary

SPACE REACTOR PARAMETER

8.0 Status of Potential Space Fusion Reactors

FRC PERFORMANCE AND RESEARCH STATUS

FRC research status for meeting key space reactor

Limited study. Requires design.

Limited conceptual work. Has not been addressed.

(a) low:lNtol0kN (b) medium: 10 kN to 50

Requires a large plasma volume. 103t0 10 e. Can burn D-3He.

Needs design study. Requires testing. Needs design study. Requires testing. Limited analysis done. Burn experiments required. issue. ~1 GW.

Requires design study. Requires design study. 30% calculated.

None required. Work will demonstration. <2%.

6.1.11 Dual Mode Operation 6.1.12 Mass

6.1.12 Efficiency 6.1.13 Recirculation Power

Requires design study. Requires design study.

the the FRC to succeed.

6.1.10 Electrical power variability

produced Failure Tolerance

The rationale by the large

6.1.15 Modes of Operation

6.1.18 Space Environment

fulfill importance

6.1.7 Throttle capability

of system parameters

Requires design study.

6.1.8 Plasma Stability

6.1.9 Power Level

with the use of

great plasma

for number

Appears 90%.

this confinement

follow net power

6.1 16 Low/no

are D-3He

at net power

in considering

the capability

the optimism

is of utmost

requirements.

this design

is exhibited

in meeting

of charged

importance.

is believed

The major

associated

unknowns

neutrons

capable.

concept.

particles

stability

fraction

6.1.17

space

which

large

favor

8-12

The

X X

But

the

will

1 I .,-‘Tp

.In c

13_”-

P3 E

FSL-88-121

power

specific

density,

of greatest

high specific

power density.

interest thrust,

power to achieve

Thus, a 400 MW reactor

could range in size from 60 to

are high specific impulse.

8.0 Status of Potential Space Fusion Reactors

as shown by Fig. 8.4. 800 m3.

to space propulsion and variable, is high fusion plasma

power, The parameters One high reactor parameter For the FRC burning D-3He the fusion power can vary from 0.5 MW/m 3 to 7 MW/m 3

in the form of 14.7 MeV in the FRC edge in very high in Table of a 1 GW FRC reactor are for a pulsed D-T system such as CTOR and for a the 14 D-3He system. One observes steady-state

The FRC is ideal beta and power density losses, protons. layer plant efficiencies. 2, where the approximate compared conceptual

Dr. Tuszewski summarized the optimism for the FRC at the Eighth Topical Fusion Meeting.

The importance the reactor’s have a power density given magnetic

that from the fact a FRC 13of 90% will at 7% for a

of 13in the design of a compact scales

lOO Ion Temperature,

direct converters, features

and most of These charged

power can be diverted

Its high plasma little radiation

Fig. 8.4. FRC Power Density

the fusion particles

of Los Alamos National

the D-3He fuel cycle.

as 132. Consequently,

160 times greater

allow substantial

These attractive

than a tokamak

power density

field strength.

are illustrated

the rationale

electrostatic

parameters

for use of

Laboratory

reactivity,

resulting

TI [kcV]

towards

roughly

is clear

reactor

8-13

ooo

that

for

o n

0.1

c o

i,ii

larger

protons,

large-orbit

Inherently,

and possibly

8.0 Statusof PotentialSpaceFusionReactors

The FRC research issues which need to be considered are:

MeV neutron production with D-3He can be reduced by about a factor 100 compared to that of the D-T system. Another (possibly crucial) advantage of the D-3He system is that gross FRC stability may be achieved at s ~ 10 with the help of high energy neutral plasma beams, elongations. This may not be the case for the D-T pulsed system at s ”. 30, in spite of the alpha particles. (Tus88)

In Section 4.0 the rationale is forwarded concerning the importance of using D-3He as the reactor fuel pair, and in Section 6.0 the system requirements are presented. The FRC is a reactor capable of burning the desired fuel, D-3He, as the FRC design readily allows for the direct discussed below. conversion of plasma to thrust or electricity. Stability during testing has been satisfactory, apparently greater than predicted. Stability, however, remains a concern, and a large experiment (LSX) has been designed to address both stability and confinement. At the present time a detailed steady state reactor study has yet to be performed.

The Los Alamos experiment reported observations of internal tilt which is the first occurrence in what has otherwise (Tus91) required of

The Large S Experiment (LSX) at Spectra Technology was designed to address these stability and confinement issues. It commenced operation in August 1990 and is scheduled for termination in 1991.

(b) confinement scaling with increases in S - a measure of the number of average ion gyroradii between the field null and the separatrix

One recent Propulsion Kernbichler, FRC. The analysis many densities propulsion

burning D-3He in a offers power to provide by Fig.

illustrates in forming the basis for a program strategy.

in Table 8-6 that to space power, It appears more suitable

study addressed with a Field Reversed (Cha89). and Heindler

the features and a good confinement

Configuration” The study examined

(d) steady state operation (preferred).

The authors in future large-size

been a grossly stabilizing

instabilities stable device.

“Space Fusion Miley,

are important scheme.

this concept i.e., high

than the other experiments

in the study as shown

(a) gross stability

the FRC’s potential

by Drs. Chapman,

testing and assists

This work clearly

the importance

for propulsion:

as presented

techniques

concluded,

“Additional

conclude

reviewed

will be

FRC’s.”

8-14

that

Beta

Thrust

Particle

(Power)

concept

—Average

production

O — Good

The power

from a study

the FRC for

Power Density

(Power)/Weight

Field Reversed

Tandem Mirror

was developed

Spherical Torus

Specific Impulse

(Mi178 and Mi179).

Fig. 8.5. Comparison

Charged Extraction

Fig. 10). electrical

Propellant Thermalization

8.5 (Cha89, commercial

8.0 Status of Potential Space Fusion Reactors

Fig. 8.6. FRC Neutron Power Fraction.

of Reactor Experiments

a high percentage

Ion Temperoture,

low percentage

by the reaction

this and a

ion temperature.

The implies

first parameter

is high power

for Propulsion.

of neutrons.

of charged

For space

production

propulsion

generated

t- O :_ (J ‘-1

particles

function

density.

neutron

interest

—Poor

shows

as a

l’keV]

FSL-88-123

8-15

10-2

Fig.

o f,_ EL

8.6

the

I,,_

10 -1

t- (3_

1 O0

B..

..,=

for

not

the

2/1

the

but

this

can

that

wall

With

keV,

loss,

refer

fuel.’

does

Space

leads

down

worth

Thus,

depth

fusion

noting

3He/D

further

supply

energy

reduce

density

out of

roughly

fraction

interest

domain

beyond

Particle

justified

neutron

brought

linearly,

external

domain.

reaction

(Ker88):

is seen

percent.

Increase

shielding

8.0 Status

it seems

provided.

externally

of Potential

is treated

to D-3He

in greater

Therefore,

production

of 60-200

to several

(T recycle)

this value,

requirement

to between

confinement

neutron-free

the ignition

by neutrons

and a third

ratio much

temperatures

It may also

This subject

logarithmically

as a function

Fusion Reactors

on the order

(no T recycle)

carried half

as a ‘potentially

can be reduced

with the neutron

In the parameter

from 80% (D-T)

will be below 2%.

a if no 3He is

neutron Dr. Kernbichler

t-” 102 o E I-=

FRC Confinement

in Fig. 8.7.

temperature

is shown

Fig. 8.7.

8-16

Time.

Temperature.

FI3”L-B8-127

II1 E

lOO0

¢p vl

[keV]

100

Ion

T i

1 I

L.—J

o ID

I c I,.

8.8.

The

burn

FSL-88-124

by Fig.

improves

efficiency

increases

quantifies

u .o10 I,. IJ_

the effects

The figure

in _: as shown

time on fuel burn efficiency.

with of confinement

8.0 Status of Potential Space Fusion Reactors

Helium-3 Burn Efficiency Fusion Power

Ion Temperature Mixture Ratio for 3He/D

Ion Temperature,

TABLE 8-7. Field Reversed Configuration

Fig. 8.8. FRC D-3He Fuel Burn-up.

Magnetic Field Beta

(FRC) Space Reactor Parameters

Specific Fuel Consumption Rate

3% 6.4 MW/m 3

Electron Temperature

5.2 x 10 -7 kg/m3s

to be addressed.

FRC to deliver

86 keV 60/40

Neutron power

is a concern

in Fig. 8.9.

Confinement

performance

that needs

be looking

The fusion

is depicted

parameters

we would

2 seconds

Jet Power

as shown

5 T 0.76

(helium-3)

by Table

a space

TI [keV]

following

concept

reactor,

66 keV

engine

design

1.9 %

29 %

then,

Time

8-17

Fuel

loss

8-7.

For

the

for

field

coals

thrust

propellant

pla.srno reg=on

magnetic nozzle

Fig. 8.9 FRC fusion engine concept.

8.0 Status of Potential Space Fusion Reactors

efficient through produced magnetic 1015 to 1016 ions per cm3. A reactor of manned programs Table 8-8 (CHA89, stability

The FRC, as can be seen from the figure, of Engine thrust topography. of a portion of the plasma directed or any magnetic design, moving parts, such as high speed turbines Main Engine),

by virtue release of this of high wear as used in the SSME (Space Shuttle the

by the release of plasma Thrust imposed by in the range of by the required by a very high

the long life time by fuel is supplied are gas into the plasma parts, contain moving by to assure

SRM (Solid possesses operational pellets which simultaneously scrape-off but heating

the space program. into the plasma. by the injection injection

use. Plasma thrust a mass solely confinement

would Table 2 ). This design is considered

Thrust of propellant system will probably

is ideally suited to propulsion by the controlled is produced

this has not been studied. from the plasma;

factor, where S = r/3pj = 50. Stability is the main concern

nozzle. One advantage is the absence

plasma densities the power magnitude

the to the achievement

Thus, that are essential

imbalance from the plasma

is produced in the stabilizing

by a magnetic reactor,

features requirements

are injected controlled

external mirror magnets.

such as the nozzle of

is low as a result of

and parts subjected

by the parameters

chamber of

The thermalization

to erosive wear,

be characterized

Rocket Motor).

which currently

and controlled

thermalization

and specific

reactor/thrust

of propellant

of the FRC.

The reactor

is important

confinement

its external

the extent

is attained

as shown

to provide

limitations

inherently

The fuel

impulse

permits

layer.

8-18

I (..)

10-2

1_1.-88-116

5 0

The

Thrust

Impulse

in Table

propellant

is presented

0.4 to 50 kN

8-8 is based

flow rate that

Stability Factor

upon Fig. 8.10.

0.01 m 1.5 m

Elongation Factor

0.5 GW 80 m3

Total power Plasma Volume

Ion Gyro Radius Plasma Radius

Propellant Addition Specific

TABLE 8-8. High Power Design Parameters.

0 - 0.8 kg/s 103 to 106 seconds

8.0 Status of Potential Space Fusion Reactors

Fig. 8.10. FRC propellant mass flow rate in terms of propellant/plasma

high energy missions and specific

for accomplishing to vary

requirements innate

One is to have

the key the

Flow Rote, Fpr/Fpl

particle flow rates.

by Fig. 8.11.

thrust-impulse

performance

the thrust

propellont

is shown

efficiently

capability

expected

impulse.

Relotive

sec; T|-45

.o 10 5

8-19

,m_ lO -3

The

“rl,-5

10-7

[-]

keV

103

105

0 o

0-5

10—4

t”

‘J

”_.\

0 3

,ec;

106

keY

10-1

10 0

10 2

¢.) im

10 3

FSL—BB-120

10 5

_.T.o=5

TI ,=B6

O (L) C_

-t-_ E

T I ==243

1”p=2= sac;

Thrust,

o_ o (1) t_ C_

T [Nm -_]

8.0 Status of Potential Space Fusion Reactors

FRC Thrust and Specific Impulse as Functions of Propellant/Plasma

FRC Variation of Thrust with Specific Impulse.

flow rate with thrust and specific

The variation Fig. 8.12.

is shown by

of propellant

Flow Rate,

Particle Flow

Propellant

Relative

Fig. 8.12.

impulse

Fig. 8.11

.rpr/Fp,

sac; T, =45

lO2

lo3

lO4

104 u

rSL-ea-119

Rates.

8-20

”_” 101

keY ”_

T l =86

10 0

Tp..=5

_1”p-5

_Tp_2

,=243

I_102

keV_

=ec;

[-]

keV

,ec;

106

r-_

F—

T I

for

will

the

are

this

gas

fuel

that

2.0,

that

The

keV

Any

ions

step

high

over

upon

level.

mass

those

being

thrust

which

levels

arises

burns,

Based

nozzle

cooled

model,

engine

quickly

charge

vehicle

in the

nozzle,

powers

plasma

rapidly.

ejected

interest

(109K),

specific

on the

through

so that

indicate

exhaust

produce

injection

of great

charged.

impulses

essential

particles,

indicated

of are

a higher

thrusting.

terminate

hydrogen

at which

estimated

producing

aggregate

developed

propulsion.

divergence

The high

and Miley

approaches

Both the

is required.

temperature

approaching

is neutrally

is produced

which and

In the fusion

self corrected

In that event,

an extensively

Drs. Chapman

are the ranges

be automatically

thrust require

no neutralization

from developing

range Section

are magnetically

a need Those

exists engines

high temperatures

various magnetic

very specific

the system would

in the electrons,

a plasma charged

the in space

based to prevent

in “Mission flight.

and to attaining

low particle the

neutralization, of a means

of 0.1 to 40 kN are achievable.

8.0 Status of Potential Space Fusion Reactors

One question concern neutralization

is whether on ion engines. a charged

the thrust as ions are ejected.

as the one used discussed

D-3He is on the order

Thermalization products

output is, as a side

power consideration

Applications” Other

that need to be addressed

The power This model

to establish 2.2.11.

uniform and incomplete,

Reactor propellants,

from FRC the same

may be the ultimate

The FRC propulsion

of 0.5 to 6 kW/kg

in the maintenance

ash, and reaction

due to its higher

burning reactors

achieve factor.

of 1 to 10 GW.

of the if non-

for aeronautical

are as follows:

to be volume

in performance

considerations.

As discussed

in comparison

is to provide

is considered

is preferable.

are possible

experimental

degradation.

investigation

the volume

is unknown

to improve

temperature

with D-T.

of plasma

anticipated

has been

in Section

Relativistic

the FRC.

parametric

for space

elongation

propulsion

to define

efficiency:

Operation

a greater

to assist

approach

important

efficiency

a model

expected

a strong

available

limitation

although

concept.

Its size

is more

burning:

stability.

to orbit

volume:

Lacking

injected

burn-up

is 3%.

authors

burning

stability

on the

studied

plasma

Limited

plasma

subject

studies

ignition

Steady

difficult

reactor

in the

earlier,

means

in this

D-3He

limited

is the

issues

(Table

higher

mode.

based

space

levels

which

factor

taken

result

pulse

order

none

note,

upon

been

data,

upon

base

used

state

size.

8-21

and,

Fuel

One

This

ions

only

8-7)

The

fuel

has

are

the

will

for

and,

reactor

burning

designs

capable

involved.

Currently

transport.

of testing

it appears

to proceed

parameters.

of reaching

be resolved

the quickest

do not scale

experimentally.

D-3He burning

the comparison

the understanding

phased manner

with the exception

due to the physics

analysis therefore,

is by full The

of some, who prefer

in the in is

by which these issues

that on the above

8.0 Status of Potential Space Fusion Reactors

and experiments has been illustrated

program, to obtain answers

reactors of MCF experiments

The only manner scale importance

Fusion conduct good agreement accomplished

of data with theory has resulted That

can realistically at D-3He by the FRC results to date.

While this approach may not be the preference and a multi-step most economical scale design may be necessary Answers 5 to 10 years. could be available Mars trip, although for the first Manned Mars Mission. fusion could become design process

Two conversion systems have been researched more extensively: the periodic- focused (PF) collector and the Venetian Blind (VB) collector. These are treated the material here other extensively

a high risk is a large risk the of fusion it will not work and

to be possible within for space the initial manned approach of space could aid in the

to proceed to a D-3He burn configuration the cost-to-benefit at

The suggestion approach, but warranted. which question research

proves to be feasible, probably recommended But if successful,

is to perform a full It

in 20 to 30 years, this is clearly not

results of presumes

as the strategical the advantages

Spin polarization of neutrons.

a reality. by the reduction

first with neutral beam and start-up

in (Mil76), and it is not the intent

that we know the answer,

the opposite of

to NASA in the process

ratio to NASA for space

therefore assumption.

fusion energy concepts,

end of refraining

not be attempted

from investigating

the FRC or other

for the abstention

If this approach

are considered

GENERATION

the spectrum,

is such that

ELECTRICAL

the feasibility

developments

an incorrect

experiments.

and to test

in time for

to address

parameters

There is,

to repeat

comprises

question

POWER

certainly

looking

energy

should

FRC’s

fusion

8-22

that

i.e.,

8.5

it.

refinement.

SUMMARY

8.0 Statusof PotentialSpaceFusionReactors

Power conversion efficiency is gained by increases in the number of stages. Efficiencies up to 87% were reported. (Mil76)

The venetian blind collector, Fig. 7.17, has been designed to convert plasma directly to electrical power via a set of biased plates.

than to make the point that a number of concepts exist with various states of technology The application has been primarily for terrestrial application with only a small, 100K, study effort for space application funded by the Air Force SOAR study noted in the study.

Direct electrical power conversion has been extensively researched for the past 20 years at LLNL but has not been pursued since 1981. Additional efforts are required to enhance the efficiency of this preferred method of electrical power generation and to reduce heat load to the walls.

8.6 The FRC reactor concept offers great attraction to space from the standpoint of a high 13, but a concern problems. demonstrated,

to have available Clearly a need exists provide,, but fusion can theoretically is frequently made in this report of program, process importance on an analytical assumptions one brief the same uncertainties.

lasers are very inefficient could be used for the mass of is that any study of an operational system, i.e., how is redundancy evaluated

The difficulty with all studies understanding one critical point, driver mass.

the FRC has experienced fusion too low to be of

source research in initiating have for space.

that The point a space fusion the hampered the

It is this lack of emphasis requiring this study,

to large uncertainties, to the initiation but

that fully understanding of

an energy this is neglected the importance

A low estimate critical point of a flight

review was made to compare MCF to ICF (Sar88),

MCF study did not refer to the FRC and project

the lack of detailed the merits of

factor has not been taken into consideration,

testing program progress

is that we simply these systems

do not have an As spaceborne.

and since this is a pulse fired system.

the power supply, at 90 MT. Another

is optimism for power

approach must make assumptions

options For example,

of it encountered

It will not burn the preferred

interest fuel, D-3He.

it takes to make either of

cannot be the above

could likely be estimated

it and during

leads Subsequent

to flight system designs.

the nature topic.

and test program that

it will have a specific

has been emphasized

the least understood.

stability becoming

system must cover

the start up power

fusion herein.

and extrapolated

but unfortunately

the ICF design

its performance

The tokamak’s

to net power.

the reliability

for example,

confinement

this nature

to a space

all aspects

application.

concerning

low since

has been

propulsion

achieved?

is among

At 5 MT,

Further,

of what

Plasma

stability

further,

studies

without

energy

testing

factual

(1991)

recent

fusion

basis.

Also,

8-23

and,

active

through

research and technological

8.0 Statusof PotentialSpaceFusionReactors

The same analogy is made with projecting

Until the reactor mass has been determined, studies can only make preliminary guesses at the performance potential of these propulsion systems. And the mass cannot be determined fusion plasma confinement until critical experiments which produce net power have been accomplished. An analogy which seems appropriate is made here with establishing and projecting a Boeing 747, a F-15, or the supersonic Concorde aircraft performances using the Wright brothers’ Kitty Hawk as a model prior to the Kitty Hawk being designed and constructed. electronic hardware performance, such as today’s supercomputer technology, subsequent to the discovery of semiconducting properties of materials. The fact is that the gains were accomplished developmental programs by the developers and users of the technology.

8-24

and

9.0

flight

AND

safety

SPACE

aspects

approval

reliability

involving

safety,

SAFETY,

In addition,

environment,

consideration

RELIABILITY,

for operational

the operational

MAINTENANCE

new technology

ACCEPTABILITY:

from the aspects

ENVIRONMENTAL,

CONSIDERATIONS

into the new system.

The new technology’s

on space maintainability

applications. is included.

the technology criteria,

of any radically careful

related matters. is, therefore,

and reliability a brief discussion

namely, that can be designed

PROGRAM ACCEPTABILITY FACTORS

among the top priority topics to address use by NASA is contingent

high energy will public the on on health impact early. upon and the This section treats of space

Public acceptance follow after only safety/environmental and the environment Acceptance two additional inherent all 3 subjects fusion issues

to the space program is made in this fusion safety and Economic Advanced “Apollo-L2, (Emm90); for the D-3He Fueled Tokamak Reactor (D-3He was a poster on in April both

Studies environmental of section. considerable Comparison Fuel Fusion Power Reactor An Advanced Khater, Apollo,” of secondary paper space applications, 1990,

and internally externally The ESECOM report points out fission fusion over of amelioration with other energy

“Apollo—An (Ku189); Emmert, Reactor Utilizing Direct Conversion,”

due to accidental The MIT report compares fusion fuels.

report in the ESECOM and MIT reports.)

the radioactive waste problem. sources and also compares

the more recent documents are the ESECOM

at the Vision-21 Symposium at Cleveland

and review papers were used to obtain

(Rot89) of and fusion

and an MIT safety and economic

the safety and the environmental

safety A comparison

the same topical material

advantages releases

by Dr. Roth addressing

of Fusion Fuel Cycles,”

“Activation (Kha90),

(NASA), was included

for the 21st Century,”

to give the terrestrial

and Safety Analyses

report, Kulcinski,

issues as identified

and environmental

by the diminution

for the terrestrial

Maintainability

Fuel Tokamak

in the review.

Environment

the candidate

as applicable

the subject

In addition,

Reliability

into fusion

application.

evaluations

the safety

constraints

the most

presented

of effects

attention

Safety

(Bre87).

(Hol87);

one of

interest

(public)

“Safety

Among

impact

insight

recent

and

9-1

for

the

9.1

and

both

in the

aspects

namely,

nominal

software

SAFETY

contingent,

(operational

in the space

the hardware,

of intended

program comprises

the system engineering

of a “system,” environment.

Three components may be considered

Safety operations operational system, environment.

9.0 Acceptability:Safety,Environmental,and ReliabilityConsiderations

We first consider fusion’s impact on public safety and the environment. Following those safety discussions, fusion’s safety relevance to NASA as the user is presented - including system safety and operational safety. Appendix B offers some additional thoughts on this subject as well. The mission reliability expectations follow as well as a very brief discussion concerning space maintenance. Consequently by addressing all four topics, a development of the degree of acceptability of space fusion can be gained and, in addition, a better understanding of the need for the capability. A comparison between fusion and fission is also included in response to requests by reviewers of the report.

In the event achieved to those strong inherent reasonable associated In other words, principles safety been

risks and the economics reduction methods. operational from a system the system has its use could

The term “environment” distinctly recent and deals with the Earth’s i.e., does the device’s

public our environment nothing operational be taken into account consideration.

inherent, for making the system acceptable that

balance with the implementation the device must the penalty

into since the flight to system safety in its

operational in its operational Problems this fundamental NASA concern.

that economically, very narrow application’s

to perform safe operation. ensue where an internal

into the space vehicle design The first environmental

such that and environmental rendered

unnatural contaminants is the “safe” approach

introducing to all. That distinctly and

will not be so great or alternatively,

The demonstration is paramount

selection or characteristics

of the system’s to a successful,

vein, system factor

is, a device must be designed

where the use is mandatory.

In a second constitutes

different flight vehicle

the system’s of

the system will be rejected

environment adversely

the system must possess

to function satisfactorily

from two is more

a and the

of important

from the habitability

from the standpoint

the space vehicle’s

or its use severely

This is, of course,

fully addressed.

system design

system safety

of any major

affect Earth’s

the resolution

issue cannot

which permit

to implement

environment?

the system’s

the designer

consideration

and product

environment.

economically

is changed.

instructions),

performance

to comprise

a significant

fundamental

environment

perspective,

is obviously

perspective

impractical,

concerning

Avoidance

properties

operation

restricted

generally

separate

equation

concern.

between

aspects.

principle

possess

residual

in that

hazard

It is a

is not

enters

factor,

safety

There

ability

is a

That

too,

that

9-2

9.1.1

i.e.,

permit

PUBLIC

SAFETY

characteristics

to the designer

to the environment?

AND ENVIRONMENTAL

for control What

that environrhent?

of hazards? is the effect

the dual safety aspects,

of vehicle system safety and impacts

How can space fusion of space

be achieved? Do these systems

the fusion engine system will perform satisfactory

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

cause high risks to be taken. The bottom line is that the designer must be able to use the device to its performance potential.

In view of to provide sound environmental protection measures and to implement a practical vehicle design using sound system safety principles, let us examine the impact of fusion on the flight vehicle and its mode of operation. What are the inherent system safety offered by fusion, both to the public and to flight safety, and what are the options flight available fusion on Earth’s system safety safe operational modes both from the environment? How does standpoint in its one gain confidence operational

This topic involves system usage considerations, system on-line to a state of operational most component. effect substances the equipment

fuels intensive antimatter with a large residue of energy waste products

the impacts only to bring the Fuels traditionally have the any other

or in general, of any system is a measure of

energy of antiprotons in matter- that can leave the Earth

the its the system on the

is the Are toxic or as part of the fusion of

Ultimately, environmental waste environment;

important of manufacturing/producing

used in the system itself? Does the manufacturing

is the environmental phase?

on the environment required

than to address. What

safety due the operation

as a part of the vehicle manufacturing

production the production

ancillary For example,

the relative hazard,

processes? requires

the fuels? process

There are a number of

unless solar energy

is the environmental

a system to the

CONSIDERATIONS

ENVIRONMENTAL

in other words,

DEVELOPMENT

consequence

the system?

environment

to mankind

the impact

of ~1000:1

expenditure

INHERENT

the mass

operational

readiness.

an energy

operation?

operations

equipment

is greater

necessary

IMPACTS

significant

questions

of space

products.

SYSTEM

system’s

What

is used.

What
What

address

bringing

on the

without

system

require

is the

9.1.1.1

impact

FROM

Three

since

and

9-3

the

for

hazard to counter and the attendant

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

The production of fuel, an environmental concern for any energy process, is for D-3He. Deuterium is expected to be benign to the Earth’s environment extracted from seawater. If solar energy can be deployed for the extraction process, practically no impact is experienced. There is the usual mining impact to obtain helium-3, but none results to the Earth, only to the moon since the study recommends that total processing occur on the lunar surface rather than by processing materials returned to Earth.

From an environmental safety viewpoint, because tritium has a 12.3-year It requires the half-life, it must be continuously bred by Earth-based reactors. constant use of Earth-based reactors for fuel production. That constitutes an additional environmental impact of additional energy and clean-up and disposal of the radioactive by-products, along with those attendant costs. An option is to breed tritium on the moon which could eliminate Earth environmental hazards. That could, incidentally, become a means to produce tritium safely for Earth utility power use.

Consider the operations involved in placing space flight vehicles into their operational environment. Let us assume that these same high energy missions are carried out using chemical propulsion identical to the mix between the solid and liquid propellants as currently employed by the Shuttle. For the Manned Mars Mission alone, the propellant mass to be placed into orbit for chemical and probably for nuclear fission systems will be nearly an order of magnitude greater than that amount used by the high energy density systems. The MEM vehicle, a chemical propulsion system, required ~1,000 MT of propellants in LEO for accomplishing a 2-year trip, whereas fusion would consume 175 MT of propellants which transports a more massive payload for a quicker, 212-day mission trip ((Zpl = 1 kW/kg). Then, consider the exponentially larger mass of to orbit. The propellants necessary to deliver chemical propulsion system approach requires energy not only for the production of propellants but also for the production of numerous flight vehicles, the energy equivalent of 37 Shuttle launches per Manned Mars Mission. Chemical propulsion using Shuttle technology will contribute to pollutants in the

For weapons related work, approximately 5 kg of tritium is produced annually at the Savannah River plant. To produce the 40 MT fuel mass for VISTA, either tritium fusion breeding, or alternatively the fabrication of ~4,000 Savannah River reactors, is required to provide a fuel production rate to meet a manned flight rate of one trip per year to Mars. The preference is avoidance, where possible, of reactor produced fuels which would contribute to the radioactive storage problem on Earth. Both fuel cycles, as a result of their use, produce radioactive materials to be disposed of in space, but the severity is reduced by those fuel cycles using reduced neutron production.

A similar concern exists for the use of fission energy for space propulsion and there will be a greater waste power. Since it disposal problem. At the present time, a national massive DOE clean-up program is being planned which is expected to cost tens of billions of dollars.

that amount of propellant

is less efficient

than fusion,

9-4

and

added

added,

9.1.1.2

instead

perhaps

IMPACT

problems

boosters.

consumed

propellant)

considered

if possible.

the nature

atmosphere

as NERVA

are impacts

best avoided,

is, of course,

in the overall

the pollutants

for propellants.

the percentage

OPERATIONAL

When considered

is a finite increase

but required

high energy missions

from the solid rocket

and Reliability Considerations

than none added, particularly

9.0 Acceptability: Safety, Environmental,

the magnitude herein are not

the effects of operating the fusion

to accomplish readily available.

(hydrogen The rare gas quantities

NEP has the same makes use of rare gasses

less The total quantity to the Earth’s

which if there is an option. eventually

the total energy used and pollutants there

scheme addition may be low, but desirable of energy environment

system both in a This topic encompasses In the case of energy release during nominal nominal and contingent mode. operations, we primarily need to consider From any the combustion products. of those fusion reactions shown in Section 4, we see that combustion products from fusion burning comprise alpha particles, protons, neutrons, helium-3, (ash) tritium, and helium-3. Of those, only and tritium, plus any unburned deuterium, tritium has a lasting environmental

Tritium is a light element and a weak beta emitter and consequently possess the safety and health threat that released presents into the atmosphere tritiated water which could cause lung damage. Table 4-1, fuel of enhanced or mitigated depending upon the particular

and charged particles. Consider spacecraft, surrounding local environment, space The local will be minimally neutrons, since they decay to a proton and electron within .-.10 minutes no lingering

neutrons. neutrons altogether because of the D-D side reactions. in the exhaust. terms of plasma confinement concepts being researched now.

As mentioned of the D-3He fuel cycle is the reduction of the neutron hazard. A fuel cycle of D-T yields 14.07 MeV neutrons reduced quantities of 2.45 MeV and 14.07 MeV and,

does not fission reactors and RTG’s do. Tritium form into the concern that some will Clearly then, as shown by

the latter fuel cycle lacks the capability to eliminate Tritium will be present viable in

Neutrons have an impact on the the flight system itself. and within of by the presence

the operational hazards to counter and reactor design.

is used for Transfer Vehicle Earth’s i.e.,

could perhaps the very high upper atmospheric

the Orbital have an effect upon on

The neutron-free fusion reactions are not energetically

particularly and magnetosphere.

causing if the fusion system

impact due to its 12.3-year half-life.

from fusion energy are a function

e.g., as could be the case for

in Section 7.0, one advantage

to the Earth’s environment.

(OTV) scale operations,

The combustion

fuel cycle used.

product hazard

Unfortunately,

substantially

environment,

large scale

environment

Ion plasma,

The Rot90

for D-3He,

ionosphere

operations,

expresses

selection

neutrons

a similar

affected

impact

paper

9-5

the

are

flux

this

and

that

The

from

have

flight.

either

which

would

fusion

safety

space

drawn

cycles

to an

These

impact

hazard

reactor

remote

is that

whether

problem

product.

intensity

frequent

particles

resulting

Whether

affecting

products

radiation

neutrons

shielding

activated

Similarly,

a strong

Shielding

to other

operation

Radiation

elements.

significant

in depth.

the flight

necessary

to suffice

operations

conclusion

to reduce

spacecraft,

is another

To reduce

of charged

and y-rays

experiments

is expected

they might

on sensitive

flight by-

and science

investigations

radio have

to determine

environmental

system and

any element.

from neutron

are concerns.

instrumentation

the deposition

to be studied

The protection

(ash) which

and the effect

during manned

is also produced.

this environmental

of neutron

shielding level.

or on Earth

significant of

in the form of x-rays

neutron acceptable

alternatives. crew

is required Heat

and Reliability Considerations

results can activate

from fusion are high

for protection from the

concern. communications

for fuel those environmentally

The most reaction energy

9.0 Acceptability: Safety, Environmental,

a not as a consequence

system fusion to perform the mission.

disposal. environmental protect

concern to orbit and during

environmental in low Earth orbit.

in an unintended threat,

Flight operations of either

that can result constitute

energy recommendations

a high specific fission

the public from the aforementioned

ash comprise From these,

in terms is to continue

nonradioactive such

are of great launch

the half environment.

The Shuttle mass fraction,

and to perform experiments

the of the neutron

in the use in

One to minimize

44x103 MT of propellant

and whose hydrogen.

is in the vehicle’s mass

reentry particularly

from errors and failures

operations Earth’s

For a manned Mars

testing will present

protection measures

it as representative

are an inadvertent

to be incorporated.

trip then, we are

of to study

the Mars mission

Core meltdowns

impact Fission

was not aided

use of nuclear

The advantage

where Earth’s

long to cause

RTG’s during

As discussed

of a chemical

and analyzed

the reductions

an additional

is sufficiently

OPERATIONS

life of many

environmental

fuels and

into Earth’s

with fission

is expressed

in emissions.

manufacture

atmosphere.

atmosphere,

contingency

considering

radioactive,

is concern

are safety

is required

propulsion.

as defined

or nuclear

the means

radioactive

substantial

operations

as helium

the fusion

measures,

that verify

preference

WITHOUT

A means

is slightly

concerns

elements

requiring

chemical

potential

extracted

particles

elements

a grave

required

particles.

hazards.

hazards

damage

exhaust

FUSION

charged

Section

reactors

Ground

fraction.

without

launch,

system,

SPACE

by the

report’s

results

manual

having

system

during

9.1.1.3

orbital

benign

debris

power

which

better

while

there

entry

burn

safe

inert

trip.

into

The

and

2.0,

flux

per

9-6

are

but

is,

for

are

any

that

1%.

less

plus

over

than

Mars

9.1.2

which

within

would

safety

fusion

space

…25%

launch

power.

vehicle

is that

system

include

Hence,

occurs,

release

System

present

operate

in part,

sources

as well

vehicles

features

efficient,

between

SAFETY

Consider

comprise

SYSTEM

Machines

properties

of energy

addresses

interfacing

depending

the result

propellants

equipment.

a vehicle’s

to payload

or system,

to achieve

the modes

the means

of ~60 to

the hazard

or system’s

for meeting

the energy,

performance.

The controls

improvements

show would

The manned

and methods

if an accident

An unmanned

the magnitude

control those

an expenditure

System safety

and operational

on the specific

to 70%, space

to LEO is required.

the art of analyzing

for a safe operation.

which the flight

specific to perform

for current 1 ratio

any added machine

occurrence. inherent

and Reliability Considerations

design satisfactorily

to prevent fundamentally

system safety the system,

9.0 Acceptability: Safety, Environmental,

can be to the detriment vehicle,

energy to determine of either man or machine.

in a MCF fusion the plasma

that and providing

that one can draw from these

by eliminating of

is due to the inert properties

fuels which nuclear with

procedures objectives

and within energy

of as low level waste

of in a fire

released. or

particles. resides

can be accidentally

obtained the

Direct Conversion”

property There

after LOCA [loss

by the magnitude

in the “Apollo-L2,

that can usually

of a terrestrial

in the magnet

was examined

the fuels will

nor chemically

not chemically

an inadvertent

by considering

is to instantly

in the former

be envisioned

the maximum

An Advanced

the explosion

to controlling

is no stored

or explosion.

the inherent

200 oC [3].

in afterheat.

for a fusion

In the latter

as exhibited

off at about

the nuclear

the coolant

in a fusion

of a fusion

that which

react with

temperature

two weeks

calculations

by shallow

is uniquely

the fusion

allow the

The main

the fusion

associated

conclusion

of energy

the effort

of coolant

combining

the fuels

to trigger

of kinetic

properties

first wall

accident],

illustrated

activation

Apollo-L2

neutrons,

hydrogen

radiation,

(potential

Tokamak

nucleons

disposed

chemical

structure

is some

powered

reaction.

tokamak

resulting

accident

Inherent

energy).

required

possible

charged

reaction

whether

remains

quantity

sources

Reactor

Utilizing

include:

is best

mission

energy,

burning

hazard.

source)

respect

Neither

plasma

helium.

Energy

lifetime

system

reactor

vehicle

reactor

fission.

energy

results

initiate

mixing

D-3He

Safety

in the

kinetic

stored

a full

safety

decay

fusion

study:

on …

levels

solely

within

Thus,

result

burial

case,

fuels.

worst

show

there

while

heat,

large

does

case

That

after

heat

Fuel

land

lose

plus

with

The

(the

The

and

that

can

first

9-7

the

…

low

level.

within

mode.

fission

reactors

to the

therefore,

reactions,

a defined

propulsion

to prevent

to release

intrinsically

will permit.

propellants,

and design

incorporated

is controlled

are required

flight safety,

Flight safety:

the machine

by operational

safe operational

the entire vehicle’s

There is considerable

approaches Hence

core. concentrated

space and inherent

for in meltdowns.

of the reactor their

release is stored within the small confines

are hand, is made at a very

on the other nature, to react when contact

by their It is their characteristic

an accidental mixing of procedures

9.0 Acceptability: Safety, Environmental, and Reliability Considerations

and power energy The potential energy,

Let us then briefly examine vehicle, considering hazards.

risk involved with their use, and extensive the fuel and oxidizer.

Inherent with fission for exists, resulting

the overall safety aspects of a fusion powered top level system failure modes,

Chemical unsafe. energy measures The hazard maintain design is only as safe as the controls

therefore of individual heat content fuel If the plasma propulsion reactor, that energy does not cause loss of rapid cooling Q (heat content) the loss of

of to the as in a space of release in results The total is small. On the other hand, in the

aids safety. the mission for a return to Earth additional to be designed

High energy With fusion the energy (RTE) abort mode. mass which allows the spacecraft.

the reactor plasma. While the kinetic energy the total plasma

the magnetic the reactor, or an explosion, of

the confines particles within the plasma is quite small.

the radiation a space points are made in Section

environment. into effect. magnet may be damaged.

Fusion is so efficient a substantial is uniformly

of a Manned Mars Mission is sufficient

margins hazards. transportation 2.2.1.

There is sufficient for a greater

kinetic space distributed,

in the conduct level

in a plasma at any given moment

only a restart may be required;

but merely the reaction.

of the plasma and immediate

to be placed the

into the design

that only a small quantity

number of safety devices

Contingency fusion,

fusion of energy.

conversion machines

Controlled releases

to abort energy

in a core meltdown

in a fission reactor

in large accidental

and to the local

or, more typically,

then in the event

time is reduced,

is extraordinarily

in that situation

to the vehicle

system option.

are additional

consequences

is necessary

is distributed

The mission

the plasma’s

are required

field is lost,

B discusses

to produce

The fusion

to transport

termination

capabilities

limited to,

spacecraft

propulsion

increasing

of safety.

Additional

measures

inherently

Appendix

reducing

radiation

presents

hazards

causing

system.

thermal

content

release

energy

cannot

control

results

within,

worse

There

large,

grave

result

case,

flight

and

For

9-8

for

the

For

can

and

The

are:

with

loss

alter

crew

have

large

Short

occur

While

mode

within

safety

fusion

failure

critical

errors.

design

modes

is not

circuits

current

reactor

to fail

known.

fittings,

cooling

stability

as we

perform

causing

concern

violently

reactors

success

are to

stresses

overheat

systems,

chemical

Hazards:

Similarly,

to revert

Solutions

magnets,

withstand

is highly

a system

of coolant

load must

unexpected

latter with

experienced

nevertheless

the magnet

Two major

is of great

characteristic

be designed

and sudden

the windings

The magnet

and mission

The magnet

the maximum

from a flight

superconducting

to a normalicy.

Failure modes:

loss of coolant.

Loss of coolant

plasma magnet

and components

from operational

from line leaks,

load with margin.

due to 12R losses.

can be experienced.

with a large structural

Plasma discussed.

dependent. well

of catastrophic

and Reliability Considerations

perspective. been have

these of be designed

the avoidance should

9.0 Acceptability: Safety, Environmental,

two failure modes strength sufficient

The and to a lesser

characteristics is no theoretical

in the structural contained

reactor’s system safety.

placed the magnetic

the reactor’s to fusion

unexpected reactor

and are not composed

in the is crucial

The use of capacitors

The illustrating

is critical subject

and system design

why a good MCF

space reactor’s

study. structure

concern, have

is best developed

with causing

to be capacitors.

by the magnetic

to the individual

hazard physics

study is very

to understanding

is the reactor’s

system safety.

be undertaken.

should fuel

the maximum

so the main

is the stored

are functions

Understanding

is a sudden

the tokamak,

not analyzed

characteristics

for a space

One source

performance,

perturbations

configuration

considerable

performance

The major

confinement

upon field.

for start-up

are unique

requirement

this points

in a fusion

dependable

importance

of moving

the FRC.

of greater

Capacitors

to space.

not been

spacecraft

categories

shutdown.

one with

accidental

presumed

discussed

illustrative

of stored

analyzed,

solutions.

be taken

in Table

however,

to have

technical

solutions

selection

electrical

reliability

powered

this the

prioritize

designs.

program

as only

specific.

stability.

a good

concern

remains

Another

system.

another

degree,

start-up

reactor,

energy,

storage

physics

margin.

System

stability

Plasma

stability

physics

change

interest

release

starting

options

plasma

system

appear

reactor

vehicle

reactor

reason

energy

to the

is the

should

history

known

Space

typical

stored

theory

again,

fusion

safety

fusion

safety

fusion

safety

There

within

areas

parts,

Once

usual

fields

while

need

were

flight

of a

work

level

start

8-3,

and

that

five

9-9

the

for

its

test reactors are built

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

Beyond this preliminary hazard analysis, the current stage of fusion reactor systems makes a more in-depth critique speculative. A detailed design is required to permit further comment upon the system safety aspects.

In burning of fusion The other source of stored energy resides in the neutrons. fuels it is high, sufficient to activate materials. The neutron energy level and flux are of such magnitude to require protection. The hazard is minimized by the selection of fusionable fuels emitting the minimal neutron flux. Even with D-3He there will be some activation of the reactor, leading to afterheat. The design has to be made dual failure tolerant to the loss of coolant failure modes.

experimental to a full scale and designed to flight operational parameters to accurately evaluate plasma stability. Safety margins must be designed into the mechanisms that assure stable plasma performance and that withstand disruptions. Expedited full scale reactor burn experiments are necessary to come to grips with this concern as quickly as possible. Establishment of scaling laws has not been as expeditious nor accurate as required for extrapolation to net power size reactors.

The conclusion is that aneutronic fusion has inherent qualities that lends itself very favorably to a relatively safe application for space missions while exhibiting other desirable performance properties needed for application to high energy space missions. But much research is needed to cause the advantages to be verified and to be realized. A significant parameter to explore in the earliest phase of a research program is the life expectancy of any plasma stabilizing subsystems and its margin of safety.

Hence, we need to seize upon those A major

costly performance procedures

this report from a fundamental

case, rare opportunities

to proceed with an inherently

elimination. which

hazard approaches

resulting operational

capability objectives.

have to be assumed.

designers the

in a more complex,

could be obtained.

and on minimizing

As a consequence

of other materials.

was to determine

of nonradioactive

be implemented,

has emphasized

with the design

With that goal

accomplishment

controls must

risks naturally

be eliminated,

The objective

In the the

is to produce

on operations

of advanced,

transportation

the designer

that enables

OPERATIONS

this report’s

commenced

exacerbates

they exist.

technology

elimination

The most

propulsion

the onset

for hazard

theoretical

undertake.

risks that

integrated

approach.

activation

if a safer

whenever

emphasis

penalized

motivation

to design

approach

elements

eliminate

in mind,

in either

to future

programs

powerful

measure

selection

inherent

SAFETY

hazards

mission

neutron

systems

defense

hazards

system.

energy

cannot

phase,

system

Where

design

added

safety

which

hands

safety

space

those

future

9.1.3

safer

flight

This

9-10

high

are

the

for

our

and

in a

fuels

unlike

readily

hazard

a lesser

helium-3

to which

tokamaks

velocities.

personnel

hypergolic

it appears

over D-T.

is primarily

in breathing

The danger

as potentially

be eliminated

Public safety

that advanced

in some cases

in the terrestrial

The MIT report

in lung damage.

rapidly or

rise to the upper

gas, being lighter

The main concern

From a personnel

reactive chemicals,

fusion fuels will not

one at a low energy

reach orbital escape

these fuels is a fact

by a sheet of paper.

tritium will simply

to the public can clearly

is, an accidental mixing of

that or explosion

current is aided during

In the outdoors, reaches of

view on favoring present

reflects a similar fuel

however, The use of helium-3,

9.0 Acceptability: Safety, Environmental, and Reliability Considerations

of deuterium-helium-3 tritium is a 19 keV beta emitter,

are inherently result propellant The difficulty program

attest. When mixed with an oxidizer, reactive as hydrogen.

the reacting cryogenic launch as is flight safety.

A radiation selection viewpoint, be stopped resulting air, will decay tritiated water. “Overall, 53) D-T tokamaks.”

the onset by the safety level which can the gas, the hydrogen than the atmosphere where it is will safely is (p. risk than

Fusion fuels, when considered safe, fire systems. with igniting will tritium will be as chemically element, in place of well as its magnitude due to the reduced present. With D-3He as the fuel cycle of choice, atmospheric makes it than Iox-hydrogen D-3He mixture from a reduction would prefer quite low.

The D-T reaction protect during placed occupants from neutrons. 16,000 km for D-T which compares (Rot90). comparison required.

With D-T, of ~3-5 MW/m 2. The use of 0.1 MW/m 2. The ensuing the type of materials the level conceivable flight

to 2,900 km for D-3He for a 200 MW reactor in to be

either deuterium or an inert as fluids only during That

to operations will have to be its of

Special a burn near Space Station Unshielded,

by the neutron flux to upon Because

heliumo3 in the is gained one is

due to the absence to the flight crew and vehicle

flux, an additional for that

systems. While the objective neutron

flux from the D-3He reaction reduced

the deuterium - helium-3 elements

reactor and spacecraft will

Freedom to protect a “safe” distance

fuel cycle lowers depending

quantity fire is a concern

are considered the likelihood

the spacecraft’s into effect

the first wall material will become

the vehicle’s with

Obviously, Unfortunately

increase exacerbating

construction. of burn

That will be the situation

using D-T than D-3He,

during space operations

time as the radioactive

safety fire safety

reduce the probability

the rate and level of

of a fire or explosion

with D-T, but some

protective measures

of deuterium mass.

fuel, but times

Dr. Roth estimates

activated for

requiring massive

14 Mev neutrons,

highly activated

of an on-board

that operational

of the enriched

are numerous,

be a function

is substantially

to be of a

the 3He-3He

is a reduced

either many

The neutron

will become

fuel cycle’s

radioactivity

occupants.

restrictions

operations

flammable

a function

increases.

inherently

reactions.

produces

restricted

shielding

reactivity

radiation

reasons,

are still

selected

oxidizer.

reduced

accrued

greater

benefit

safer

time,

level

9-11

also

that

to the operational hazards,

from the decay of tritium is eliminated.

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

quicker and more severe radioactive hazard situation arising with D-T powered space vehicles.

Operations in any endeavor comprise the major contributor to accidents. Flight operational hazards are created by an activated first wall since their removal and replacement for launch vehicle refurbishment in a space environment can be anticipated to become part of the planned maintenance activity. In the case of either fuel, robotics will be required for repairs, and shielding is needed for protection of the crew. First wall disposal, after removal from the reactor, adds further risks, and costs, ones which are best avoided, where possible.

Not only does the flight operational performance characteristics favor the use of reduced neutrons, but the the fusion vehicle system design is simplified as well. Flight spacecraft system structure can either be eliminated or its mass reduced that otherwise would be necessary to absorb the neutron flux. Heat control design problems and heat rejection mass are reduced. With D-3He the heat rejection requirement The on-orbit is either at a significantly reduced maintenance necessitating first wall removal time scale, or eliminated. Shielding of other orbital facilities or operational restrictions are substantially reduced. The impact on contingency planning is reduced, or at least simplified, such that, as a minimum, contingencies for accidental releases of tritium are eliminated from consideration.

Helium-3 reacts with deuterium at higher energy levels than tritium. Radiation losses will require considerable attention. As we proceed into developmental research with D-3He, plasma stability as a consequence of expanding the operational temperature regime over and above the lower pressure reactors will be a subject of significant research endeavors. One key D-3He developmental goal the reactor accepting a greater tolerance to plasma instabilities, i.e., the reactor must be designed to contain 14.68 MeV protons with operational margins. Verification that the reactor can be operated with a significant tolerance to values from the reactor’s design point and examinations of system sensitivity to operational divergences will be necessary for assuring a reactor’s operational system safety. The higher to temperatures contamination such that the purity quality of the fuels and propellants will be an important consideration in achieving a reliable operational vehicle. A drawback to the D-3He reaction is the fact it still contains 1% to 5% neutrons. Whereas the low flux reduces the neutron environment, a given quantity of mass is still necessary to absorb neutrons. There are trade-offs, but the balance is clearly in favor of D-3He. Emphasis must be placed on research for an aneutronic reactor design.

Any payload launched without radioactive substances will have a significant advantage in terms of less protective mass required. The costs to acquire There is a strong safety launch approval will be considerably lessened. preference to the use of space-based vehicles which are non-radioactive.

is to provide the design means for

the reactor’s

undoubtedly

sensitivity

increase

9-12

that

will

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

Some techniques to reduce the number of neutrons in the D-3He have been examined as discussed in this report (Section 4.0). More in-depth studies and verification experiments to investigate neutron reduction techniques are worthwhile. One such important study would be to establish the function of neutron flux on a flight reactor’s and vehicle’s design mass. That data would be in conducting trade studies to establish the vehicle design leverage of useful information, planning can be accomplished to neutron reduction. From that provide guidance for the level of funding for neutron reduction research. Hence, additional analytical efforts to numerically establish and demonstrate the performance and cost benefits and system tradeoffs of a lower neutron flux D-3He fuel cycle play an important role in space fusion research.

radioactivity Fission reactors present inherent safety hazards. The reactors’ level will increase significantly with use. Unfortunately, the probability of need for maintenance attention to the system will also naturally increase with system operational time. EVA repairs on an activated reactor will not be possible. In fission, heavy Instead, robotics will be required or the reactor abandoned. radioactive particles will be produced in the exhaust which will settle on the surface of the moon, or Mars, or will be deposited into space including LEO. These elements typically have long half lives and high energies. There will be a significant mass penalty for shielding of the crew since the particles are at a higher energy level. There is a hazard, too, in the result of a strike to a reactor by a meteorite of sufficient size and velocity causing damage that results in the Unlike ground release and spread of contingency operations, technique to clean up the radioactive debris in space. Perhaps these are concerns that after detailed that is, the probability of a damaging study may be found to be insignificant, strike may be acceptably low, but the option to eliminate these hazards is preferred.

9.2 SYSTEM RELIABILITY the performance If man is to settle Mars in an economical, safe manner, the Manned Mars Missions will necessitate new design requirements for approaches and operational standards which contrast significantly from current expectations of rocket engine performance. Instead of burn times of seconds, as expected for solid propellant motors or minutes in burn durations for liquid it takes to run a fusion engine for a engines, we now must examine what continuous burn duration of two months. Based upon the proposed design using magnetic fields, magnetic nozzles, and the lack of highly stressed moving The obvious parts like turbo pumps, primary concern is the damage that the vehicle will sustain from the accumulated neutron exposure over those operational periods.

Beyond the Manned Mars Missions, to perform the more distant high energy reliability requirements missions - particularly those beyond the solar system -

radioactive materials there is no way practical

that approach appears reasonable.

in space.

9-13

for

power

9.0 Acceptability:Safety,Environmental,and ReliabilityConsiderations

of a new dimension will be placed upon space propulsion and power systems. A rendezvous mission to the nearest star takes on the order of 200 to 300 years using systems with very high specific power characteristics for the missions as considered herein. The fourth stage reactor will be expected to function for approximately 50 years after being dormant for nearly two hundred years. The first, second, and third propulsion stages are each respectively expected to provide the electrical the annual or biannual science data transmissions while those stages are respectively operating in a propulsive mode. The option is for the fourth stage to be cycled once or twice annually for the data transmissions, that mode requiring a large number of start cycles being placed upon the machine over a 250-year interval. The fourth stage reactor will be shutdown at the completion of a 50-year burn period. Then it will again be called upon to transmit science data twice annually for another 10 to 20 years after completion of the thrust mode.

To accomplish such a mission, new standards for flight system design reliability must be set. On-board self diagnostics and corrective measures will be required to avoid system divergences. This will set new standards for diagnostic tools for artificial intelligence by flight vehicle systems and for self corrective tools to remedy undesirable situations before they occur. Once if the shielding can be adequately accomplished within the vehicle’s again, specific power limitations, the magnetic confinement of fusion plasmas and thrust conversion and vector control appears to provide a reasonable technical approach. Reliability is achieved by the inherent capability of a “solid state” propulsion system design, redundancy of flow control devices, and predictive diagnostics to prevent deviations leading to system malfunctions or failure.

Fission reactors, in which gas flows over a core, will have an erosion Erosion the latter as a consequence high thrust hardware. where Redundancy important

For fission systems, mission durations of the stellar nature are not considered feasible due to half-life limitations. The question of the means to achieve fission system reliability for the more reasonable Manned Mars Mission has not been addressed for a flight system. the high reliability approaches and issues.

Fission Therefore, magnets. device. mass. that avoid the requirement.

NERVA type systems rotating flow rates large design margins will be important to be cost effective.

than system than in a static the reactor to designs are

as well as a safety concern, particles. propellant

from a controls The chance of increase

radioactive higher that nature,

Let us examine some of

to cool in comparison

the number of control cycles

to achieve system reliability.

is a life limiting concern

that such operational

resulting are

for failure is greater

are more complex

requiring of

system equipment

are not anticipated

control these

and maintenance

the design

the high wear

For hardware

repair of

in a dynamic

requirements

perspective,

of multiple

is required

the fission

considered

of ejected

Operation

actuators.

The fact

That will

concern.

systems

reactors

in flight

is also

require

reactor

to be

space

9-14

rods

and

use

9.3

energy

SPACE

system,

APPROACHES

MAINTENANCE

AND LIFE CYCLE

there will be the economic

source offers unique features

for a manned application,

engine systems with a minimum of orbital maintenance.

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

For missions within the solar reuse these massive The fusion non radioactive to name several.

imposed upon a flight system design shows that that design approach is a It will be important to provide a wide design and reliability life limiting concept. operational factor of safety with fission reactors and to avoid pushing the fission engine close to the design limit to achieve high specific power capabilities.

Design trades involving fission need to incorporate a mass allowance for achieving a safe, reliable vehicle, just as cost trades must account for space maintenance, operations, contingency planning, reusability, and life cycle expectations as well as the R&D and manufacturing costs. That is, a complete the systems approach must be taken. Ultimately, safest design approach is a redundant reactor with a test verified-high degree of margin system that is tolerant to multiple operational errors during flight use.

The entire fusion vehicle system” to the reactor. nozzle, thrust magnets stressed highly are eliminated. erosion avoided

Maintenance least, will be a very expensive required servicing storage dose rate after shutdown remote maintenance

fuels being the transfer in the engine’s magnetic reliable large parts surface

Fission achieved so simply higher due to a limited reuse capability.

not be possible or, at use of robotics will be Robotic space “The biological implying

chemical systems, High speed moving are concerned, over which mass flow occurs

than fusion where refueling can be fuels. The fission reactor cannot be to be

reuse is less of a possibility simply by the transfer of cryogenic refueled,

and require either disposal, in a shielded location. the shield is excessive

system will probably An extensive the high levels of

to replace man who cannot accept activated devices will also become

is anticipated to the greatest extent possible,

Activated materials will be a cause for restricted maintenance

for other mass and design system reliability

or storage at the back of (Kha89).

to operate the exception field strengths

or other components field confinement

are tradeoffs and in the provision

these challenges low neutron

of nozzle throats by the magnetic

so life cycle costs can be anticipated

asymmetric can be simply

that meet liquid refueling,

So while benefits inherent

accomplished. Unlike

as a “solid state propulsion

In so far as the propulsion

and low maintainability.

Through vectoring

at a safe distance,

there savings

the net propulsive

particle energy,

fuels, charged

the magnets

of a fission

is needed.”

proposition.

operations.

complexity

approach.

Inherently

in space;

necessity

radiation.

required.

pressure

flux

are not

a mass

if at all,

systems

penalty,

that all

offering

vessels

provide

impose

reactor

mode.

9.4

and

stems

strain.

flights,

benign

reduce

impulse

systems

required

Fusion’s

possible.

inherently

operations

by simply

power-high

SUMMARY

the Earth’s

fuel hazards

attractiveness

and lowering

and handling

characteristics

than chemical

environmentally

the number of

energy or

lack of chemical

the environmental

that high degree

related to servicing

have the capability

of safety systems

from Earth’s surface.

assurance all

propulsion Burning

it is a weak beta emitter,

and safety when D-3He is

The large amount of energy

impulse safer launches

required to initiate the reaction

is the feature High specific

and high specific flight

energy of high performance

from the viewpoint of D-3He eliminates

These nuclear their radioactive

are safer reactivity with each other.

space flight vehicle systems reducing thereby

9.0 Acceptability:Safety,Environmental,andReliabilityConsiderations

High specific specific the number of Earth surface-to-LEO stress from its inherent used. which makes power make reducing

Environmentally helium presents upper atmosphere will not entrapment. have an impact fission. required The space fusion products with the exception

the into the fuel hazard, are tritiated water and local to fuels is not expected and propulsion on the other hand, as

the fuels system,” a necessity cryogenic of an oxidizer, These are controllable.

requirements of deuterium and 3He which has a substantially in orbit or another

The charged approach D-3He deuterium neutron flux which activate

If tritium is used, fusion radioactive capable simply fission, all of highly concentrated

unlike The production of by the VISTA concept would be expected

It is self contained. With core, a relatively

fuels, but also from the standpoint fusion’s

hazards in the presence first wall materials.

The main concerns the deuterium and helium-3

The fusion selection Refueling transfer

shuts down if a problem occurs and any damage

D-3He of of not being

to have a significant of all environmentally

by the neutron flux. by a fluid

for the long trips. fluid

temperatures, and a reduced

is safer low radioactive

are simplified reduced

is stored within the reactor’s

not only from the absence

fuel cycle’s of

for a “solid state propulsion

is a very sound approach.

it no hazard;

and tritium is expected

is simply accomplished

first wall maintenance

where the breathing

the only radioactive

offer an inherently

having a 12.3-year

to rapidly disperse

ash from burning

the large masses

is stored within

impact. sound

sound For

“ash” tritium.

on the Earth’s

pose a threat.

of excursions.

than fission,

is comprised

the vehicle’s

the plasma.

environment,

If accidental

fundamental

fires when

operations.

the main,

Production

operation.

inherently

planetary

chemical

reactor’s

releases

typically

half-life.

hazard,

source.

particle

energy

tritium,

All of

occur,

body

used

9-16

are

its

and

10.1

10.0

THE

AND

SPACE

FUSION

fusion

energy

SPACE

-MISSION

VIABILITY

enabling

question

STRATEGY

influence

follow-up

approach,

capability

FACTORS***

PURPOSE

for space.

PROGRAM

APPROACH

ECONOMICS

the mission

EVALUATION

the program

The primary

the program:

OPERATIONAL

and feasibility.

IMPLEMENTATION

status, or not

***KEY MANAGEMENT

AND IMPLEMENTATION

technical whether

Hence, we examine

ECONOMIC-PROGRAM

Earlier we examined

the factors which will

the current management

structure will accomplish

then, we consider energy.

to NASA with part of any

the challenging 6-8.

directly all of which

to NASA from the presence

reached is enormous.

the priority this section,

it consideration

In this and without

among to consider

the relative economics

activity undertaken,

resulting a significant

energy of a space

program is primarily

commitment technical

economies constitutes

determines purpose

conclusion systems

of therefore,

strategical all

reality functions,

is the organizational

AGENCY COMMITMENT
PROGRAM PRIORITIES

in the development

the implementation

one step beyond

system to focus

will be exhibited

to organizations,

factor utmost

been discussed

by the funding

A new NASA

CONSIDERATIONS

be a function

of a program.

This linked

the economic

to accomplish

flight fusion

considerations

Consequently,

and mission

-ORGANIZATION

is necessary

from fusion

the their

management

achievement

the means

commitment

to address

of a space

of NASA’s

in Sections

to achieve

the proper

advantages

the purely

a program

and since

to develop

is perhaps

economical

the actual

the fusion

importance

OBJECTIVES

conversion

to fusion.

economics

objectives,

endeavors

resources.

competing

the most

capability.

overriding

ECONOMIC

is made,

the next

is based

economic

capability

In order

structure

strategy.

planning

Whether

program

proceed

benefits

realized

is that

matters

funding

desired

provide

results.

section

energy

or not

assure

occurs

space

fusion

space

fusion

space

fusion

would

is of

levels

which

Since

upon

need

upon

likely

once

goal.

have

most

topic

level

10-1

That

gain

The

that

are

the

will

for

their

energy

Economics

strategy

10.0 Space

strategy.

research

yardstick

priorities.

expected

from the

and Program

execution

Implementation

a funding

for space

to resolve

roles and

the current

is discussed

governmental

organizational

the level of

an evaluation

into spending

The approach

Program Operational

NASA What

of organizational

in the development

therefore, those of

research dividends

a space fusion capability

taken here is to develop

Hence, it producing

the and results

of consideration

as discussed fusion

Thus, of managerial

factor structures manner

the respective assigned

on space which in Section

in a timely of a space fusion

and DOE, in are the products

fusion as an investment

and the likelihood is also an essential

the logic for the strategy considerations

and the recommendations and rationalized.

incorporates roles upon the objectives mandated

from the two by using flight pays 2, we

like NASA and DOE are instituted line needed to meet problems.

the influences of examining Looking fusion upon in terms of operational a funding

This section, the influence organizations, responsibilities. agencies? the technique operations. tremendously can establish applications. viewpoint

Organizations along the very specific results focuses recommended a prime consideration, the NASA missions

of this section, can make upon the NASA mission in the application

program goals. space fusion program for NASA, one must

generally focused upon which the agency

upon the relative impact fusion

The end objective fusion energy that

if we compare and

for fusion energy for space.

FOCUSED AERONAUTICALRESEARCH

differences, strategy

the DOE to examine

FOCUSED SPACE RESEARCH
DEVELOPMENT PROGRAMS

in the development

MULTIFACETED PROGRAM:

take into account,

are accomplished

and constructed

by very specific

is to concentrate

Further, their

FLIGHT OPERATIONS

the uniqueness

The problems

.UTILITY COMPANY

of a program

the objective

this process

of producing

its missions.

DEVELOPMENT

NASA MISSION

with those

in deriving

DOE MISSION

similarities

particular

guidance

provides

,RESEARCH

DEFENSE
CIVILIAN

-OPE_TIC_SPOI_

a as

Thus,

then,

10-2

-_MOTIVE

for

one.

or not

energy

difference.

program goals

fusion energy.

It is the function of

as a source of power

For NASA there is a profound

of commercial to operate

the generation the public utility companies

on the principle enhancing That distinction difference

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

profit versus space mission achievement perspectives

role as well as an operational of whether to meet

the It has both a Instead of profit motives, we

the fusion device is mission enabling for a

in major variations in energy. Mission differences do require and result In examining mission differences, one must consider program funding levels. all of the various elements of which programs are comprised in order to optimize system or mission costs. There are two major components in the final the mission cost equation for organizations like NASA and DOE, namely, investment costs and the operational costs. developmental

With regard to these two components we note a significant, and fundamental difference. DOE’s mission is energy for defense and utility electrical power needs. Fusion research comprises only a very small effort in the total DOE budget. For terrestrial fusion energy conversion, the ultimate goal of DOE is to develo.o electrical fusion system profitably. develo.omental operate or mission science. fundamental

This analysis deployment then estimated an understanding merit was derived level of reasonable and a program spacecraft. undertaking

on the initial cost considerations costs. trades,

of investments to the implementation

space were Then, from a figure of the

competitiveness is a major difference flight missions

program, NASA, unlike DOE, aspects

Day-to-day of space mission operational

of a flight for NASA are a major

in the end is responsible of

first costs. from analyses

between versus the production

operational costs and day-to-day

the cost equation, fusion

namely, experiments powered

Flight operational a program of

of energy the two agencies

the other developmental

fusion consideration

is the goal. Consequently,

for the flight oDerational

The flight deployment

In DOE, demonstration

fusion operational

power, as discussed

FLIGHT OPERATIONAL COSTS

creates

with other sources

the total mission

by the execution

in organizational

INITIAL DEPLOYMENT

first principles

of commercial

there of

its missions.

as exhibited

this nature

be divided

and goals.

in contrast

operational

component

exploration

categories:

the effect

for space

and cost

economic

considers

with the

terrestrial

DAY-TO-DAY

of for

leading

energy

below.

space

costs.

costs

since

initial

10-3

can

into

two

for

that

Thus,

10.1.2

10.1.1

AGENCY

COSTING

to assure

depending

PHILOSOPHY

DIFFERENCES

PHILOSOPHIES

This difference

costs incurred.

is to accomplish

IN ORGANIZATIONAL

its mission with minimal

upon mission objectives.

piece parts serve as an insurance

As an illustration of this key point,

in the space program we willingly pay a

the same hardware used in other programs.

is to And the the The total

objectives within the allotted cost and time constraints.

even more pronounced in different organizations that have different missions.

10.0SpaceProgram Operational Economics and Program Implementation

accomplish goal of the programs within organizations

is comprised of the sum of all of its elements. the acceptable

Clearly one major goal of all agencies, or any organization for that matter, successfully fundamental mission

To minimize the program cost total program cost, however, costs for any specific program component, or hardware, can vary from agency to agency and from program to program, the minimum tota/ program costs are attained, some programs may well consider a higher cost of its components to be an appropriate expenditure over that spent can become for

The high reliability premium price for high reliability electronic electronics the space electronic circuitry may be similar to that used in various terrestrial consumer is more extreme and devices, the economic for consumer rigorous testing of space hardware is required to eliminate products. The philosophy adopted potential defects or marginally performing hardware. for space programs is to provide a high degree of assurance that an electronic piece part will not fail during the systems verification checks while in launch impact of a failure is at the count down or while in flight. initial testing. time of hardware along the launch The cost of

processing flow path. The costs from failure dramatically escalate as the time of costs to achieve high launch approaches. reliability, when summed over the investment costs in the acquisition of quality parts. Those added reliability costs would be dwarfed by one launch delay. The cost of failure in orbit is even much and the like, on the greater. Manufacturers product, would other hand, with their consider product mission

Similarly, rechargeable $2,000M spacecraft, (LEO) of more than $300M and the impact of mission favorably expenditure

cost premium for The rationale is obvious. A $500M to to low Earth orbit transportation trade very by a small energy

insurance which is provided reliability for

in their mission to produce the least expensive

the entire program, can more than pay for

the space application’s operational

Those additional quality assurance

the additional objective

as the vehicle progresses

space qualified batteries.

The least expensive

reliability measures

plus the additional

radios, computers

policy. Whereas

than an order

we pay more

the additional

higher battery

of magnitude

of televisions,

for achieving

consequence

piece parts.

incompatible

of meeting

environment

international

competition.

possession,

far greater

acceptance

component

than that

Additional

consumer

increases

of funds

namely,

toward

failures

severe

failure,

space

failure

flight

cost

10-4

all

cost

likely

cells,

funds

10.1.3

fission,

IMPACT

be more

MISSION

for ground

one would

is negligible

constraints.

VARIATIONS

OF AGENCY

the differences

and not worth

The t_rrestrial

systems which

fusion Drogram-

in most situations

the mission cost

its failure to ground

or hydraulic power

operations trade.

and Program Implementation

cost $200K to $400K.

the mission performance

not spend those additional

for utility power purposes,

in the two agencies’ missions,

10.0 Space Program Operational Economics

objective of producing an energy

But to assume simply

trade between programs in agencies

and environmental these alternate

of the space program’s

the degree products, and the requirements

storage rechargeable failure and would

applications the risk of battery the impact because

particularly with regard is enabling to which the technology imposed upon the technology. With like NASA and

Consider to the operational versus enhancing, fusion, DOE is different due to mission differences.

having the goal of providing a means for the generation of utility power- must meet conversion system which is cost compatible with the other current energy sources that and to do so within the include coal, crude oil, required safety it will not succeed. are competitors with fusion. As shown later in the DOE fusion Thus, cost energy delivered to the equation network grids for utility company use. product for use by industrial concludes with the production of safe, economical reside for that No further performance and individual consumers. program. is considered to be Thus, appropriately keyed to advance at a rate compatible with the terrestrial energy cost projections.

the mission Technical fusion requirements to be as and the space application as the difference between a diesel engine designed for a diesel pronounced locomotive aircraft, or as the fission and a turbine designed for commercial reactor for use at an electrical utility company compares with the space nuclear

There is one other major mission consideration. fusion a fundamental the two agencies. complement nor operationally more economical DOE is not concerned with budgeting reactors. results in a difference That agency priorities as well.

For for some space missions, in the missions of difference is only a energy enabling” Fusion is not “mission the its office to operate utility company fusion not only in technical

the SNAP type space power plant, although each of those the reactors will on Earth,

The electric utility company’s power requirements level

fuels. in the physical environments where the respective

power plant, i.e., pairs respectively differences operate. Water

number relative cost of electrical

between for are anticipated

and the implementing fusion

to the existing energy supplies.

than current energy supplies.

reactors is readily available

is an enabling technology,

hardware applications

fusion program funding

for cooling terrestrial

take into account

is the anticipated

the terrestrial

requirements

applications,

One must

differences

Otherwise,

terrestrial

Obviously

common

the final

designs

sources

energy

differ.

fusion

10-5

The

For

but

not

this

That

section

results.

energy,

mission

provided

orogram,

durations

produced

objective,

program’s

a mission

in contrast

the energy

to a space

implies that

the cost of

But power

the end purpose.

is a to the of a

net benefit on which

shortened are reduced,

that a positive is a point

are significantly launches

component application, It is a means

in the cost equation. the fusion

as a wise investment, system

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

to accomplish in space, is only one component

or where the number of Earth orbital for NASA to reap substantial

exists advantage economic is not economically

In the space significant terrestrial mission. That energy space concentrates.

in the space program, we would readily accept a higher cost of to the tota/

It is shown that, where space missions fusion opportunity economic program’s envisioned, in today’s

whereas NASA relies upon radiation cooling in space. The space reactor has a ready supply of vacuum available whereas it is naturally denied to the Earth bound reactors. Maintenance is a different problem altogether for the two applications where, at best, space may be considered relatively inaccessible in many situations and absolutely so in other cases.

the cost of fusion energy is only one part of the system For NASA’s missions, the mission being ultimately to conduct science and to move man and equation, For cargo through space to conduct space science if a fusion energy is the means to the end, not the end in itself. Today, space, fusion reactor existed which has the properties ascribed to it in the text of this report, NASA could very well accept a higher energy cost for a new source of

fusion energy, when converted to chemical point level of

energy unlike the power companies, permits advancements.

economic contrasts with the terrestrial as currently sources

As shown later, to space performing since its budget costs.

power of as compared That is a critical a very significant

fusion If fusion were an cost of present

Paradoxically presently program’s engineered electricity

utility electrical its currently of plants would

enhancing noted in this report,

inability available exploration.

fusion by the mission

But it were role in space

of power. conceived

consideration for operational

Fusion, used energy

fusion. with currently

economically today,

and exploration missions.

to compete for space

From the considerations

for NASA’s funding

economical because

energy be playing

fusion incentives

sources. a major

idle due to fusion’s

at a rate determined

governed goal

the United States’

energy economics.

a lesser mission.

the new energy

either mission

is unfortunately

provided that

by the The

fusion would

technological

OF FUSION

does include

the terrestrial

ON SPACE

or mission

is enormous

development

advantages.

international

to develop

the energy

economies,

SYNOPSIS

with other

to develop

MISSIONS

compatible

it appears

leveraging

costs for

to space

capability

enabling

currently

energy’s

COSTS

source

(COE),

10.1.4

higher

today,

power

space

those

1 0-6

that,

sit

first

that

10.2

costs

fusion

safety

10.2.1

below.

LEVEL

conduct

reduced,

program.

VEHICLE

enhanced,

REACTOR

technology,

Operational

is provided,

and quantity

MANPOWER

into a space

OPERATIONS

AND FLIGHT

OPERATIONAL

a new mission

level, wear out

cost advantages

and development

of work performed

Each are discussed

rates, and recurring

science missions permitted,

an advanced because

These will have to be factored

this new fusion space mission

task accomplishment factor.

fusion were developed on a scale not otherwise

for NASA are a function costs traded

enabfing more from science space

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

and more data returned now, man could permitted.

with the availabifity capability data intensive missions. If space exploration missions

Let us now evaluate operations. operational manpower speed of efficiency design

some of the key cost elements which are unique to space of the against

an operational system

The capability for important reaction response transportation the vehicle’s accommodate lengthy philosophy duration missions which tend to be more closely monitored.

Consider space fusion systems most stringent mission demand systems year distances, artificial conduct AI aspects thereby spacecraft’s The spacecraft must possess then spacecraft, control of the spacecraft

for The systems, which tolerant 4 light of in-situ operational

is based the round trip data two thirds of system design must the

flight. regarding the vehicle system’s for operating the vehicle’s mission to fly itself.

where time is on the order of 8 to 10 hours for and Pluto’s

such as with an Alpha Centauri (AI) was alluded to earlier of

time is in a thrusting mode, errant That

intelligence of science missions. for missions, systems,

distances. the vehicle’s behavior without waiting

degree the great distances those for stellar

fault time, beyond The importance

accomplishing the intelligence and

in this category the propulsion

spacecraft is a suggested

self correctable of

self detection, in situ.

for the planetary

constant non-thrusting,

acceleration, low velocity

the delivery that endure

and correct response.

diagnostics, Included

and system requirements

occur, by the and

long thrust spacecraft

of unerring for

of objectives,

lengthy, multicentury

to fly with minimal

must be achieved

time at Neptune’s

be accomplished

and the current

or, alternatively,

and controlling

the spacecraft

the innovative

are guidance,

in operational

In the context

If key failures

repairs must

of autonomy

and speeds

the Earth

navigation,

particularly

objectives.

assistance

is equally

difference

important

missions,

involved.

Because

between

vehicles

system.

periods

and of

human

fusion

Earth

flight

10-7

the

for

the

Let

and

that

cost

flight

least

those

fusion

10.2.2

fission

space

further

study,

extent

Space

There,

Fusion

reactor

SPACE

involve

needed

24-hour

reactor,

reactor.

support

aspects

FUSION

“reactor”

relevant

requires

examine

involved

systems,

of what

REALISM

terrestrial

personnel

the year.

less than

REACTOR

To better

magnitude

a concept

operations

throughout

operational

10 people;

understand

to a space

us attempt

in principle.

autonomous

The “Dense

experiments.

are included

approximately

is such that

the estimated

AUTOGENOUS

involved with

the magnitude

let us examine

accomplishment

Is an Autogenous

system objective,

reactor rather

of the autonomous

ground systems

All plant activities

Contrast persons

300 to 400 persons

Z Pinch Experiment”

the level of manpower

in that number, many

that can be considered?

which are not applicable

a staff of operation

is used for a continuous

it with the level used for

is on the order of $300K.

compare approximately

at Los Alamos

10.0 Space Program Operational Economics and Program Implementation

that with the large fusion experiments for a large machine.

and test personnel, than

reason than due to the requirement

as the loading triggering

that be determined

state of hardware

of pellets with fuel, pellet

will have to be performed

Can the trend be such

That accomplishment

than with any other

are now performed

as being suggested

for the development

exist, consequently,

flight identical

and the generated

is not achievable,

using a trained

to be developed

through That

staff diminishes

by the wear-out

to be measured

an encouraging

or by providing

The parameters

and motivation

such ignition

if for no other

the application

flow of fluids.

of a concept

flow controls,

tasks which

other means

of operational

OPERATIONS

by intelligent

any moving

comparisons,

ICF systems,

is concluded,

the electrical

in flight will

temperatures,

accomplished

be the goal

the number

mechanisms.

to be built.

With MCF,

as a “solid

Nevertheless

as a space

temperature,

fundamental

for mission

successfully

of support

redundancy

to achieve

propulsion

traditionally

parameters

operations,

importance

to control

from the

the thrust

FACTORS

and flight

conclusion

operations

that goal

by these

and very

are they

undefined

Obviously

to zero?

achieving

primarily

are not

system,”

likelihood

rationale

reliability,

absolute

magnetic

to serve

technical

Perhaps

is much

are not

indicate

is, one

program

devices,

demand

that at

FLIGHT

defined,

without

concept

ejection

system.

RATES

margin.

a high

precise

coined

plasma

in this

greater

include

values,

system

in the

sense,

require

reactor

strong

WEAR

control

should

design

status,

design

restart

10.2.3

either.

trend.

COST

drawn

power

There

parts.

fusion

focus.

active

totally

these

which

some

using

staff.

level,

state

basic

since

know

least

data,

have

AND

flight

least

flight

rate.

here

OUT

FOR

they

may

10-8

fluid

field

that

The

fully

was

that

and

has

Nor

but

the

will

yet

for

and

based

10.2.4

control

plasma

analysis

is not a

detection

None of

promising.

to involve

the current

the obvious.

RECURRING

for example,

upon current

The software

of net here,

and modeling,

flight operations.

to be reasonably

as is necessary,

the goals we set

be achieved must

the high frequency,

and that, of course,

those, millisecond

forth here can ultimately

to maintain of

fusion power. the required

until the prevention

away from the wall. stability

techniques The development and transport

review and analysis, much of which awaits the determination

the Space with code for the accomplishment

10.0 Space Program Operational Economics and Program Implementation

from the initial considerations does appear

tasks for fusion experiments recently. the tokamak,

task position in a location for understanding

of has not been complex, Those measurements

or not Whether receive extensive of least of autonomy

the means to achieve the safe and reliable production given to the subject

knowledge, system responses, Shuttle Main Engines’ control actually, include the the research is another matter,

name some appear such turbopumps. and housekeeping a manual plasma plasma codes involving Crays for research for requirement

Estimates of COE (cost of electricity) are periodically made by the terrestrial fusion reactor power plants, of merit for fusion particularly in relation to current power cost effectiveness to better define those costs. plants. The ESECOM study was a recent attempt The community generally considers the tokamak COE to be in the range of 50

The cost of here is to decrease the space flight and impulse. performance launches other performing consumed selection.

For purposes consumables orbit, the major Scheduled maintenance

fuel cost of is minimized with the proper

Let us then consider in terms of setting program priorities.

consumed is relatively of mass placed into orbit by either

consist fuels - plus the costs to deliver

power power and impulse the number

program to establish figures to establish fusion’s

the economic importance of fusion to the DOE and NASA

of than any for fuel fuel

flight of the fuels to low Earth

in the implementation cost. recurring

greater mission The recurring

primarily cost

In the case of offer

of high energy missions.

product the quantity

times or by an increase

Scheduled maintenance

objectives fusion

FOR TERRESTRIAL

the cost advantage

to low Earth orbit

system missions

the high specific

in the propulsion

Thus the trade

system specific

COMPARATIVE

this document,

fusion energy,

to accomplish

of drastically

the quantity

ECONOMIC

At level

the energy

lengthening

is another

the solar

the costs

developed

FUNDING

AGENCY

recurring

is small

is small.

reducing

currently

sources.

FUSION

ISSUES

COSTS

LEVEL

energy

10.3.1

small.

factor

since

costs

10-9

10.3

rate

10.1

least

$400

$450

trend

since

$5O0

fusion

o 1:3 “6

United

plotted

States’

$300 _

$350 _

in Fig.

beyond

initiation

program

energy

spending

Current

maintains

in 1954,

is shown

capability.

(anom87).

for MCF,

available

the current

The annual

decreases,

40 mil/kW’h

35 mil/kW.h

the professional

rate, one which

the production

costs approximately

utility fission energy

costs of there

to fund the development

using crude oil. Until

10.0 Space Program Operational

little incentive program

rises as the crude oil supply

Economics and Program Implementation

on the part of Congress much

to 100 mil/kW’h. and approximately commercially will be relatively of a terrestrial

Fig. 10.1. Historical Magnetic Fusion R & D Funding, 1951-87 (in current dollars).

the Japanese where

at NASA the agency

a program at

only saw fit to fund

it at $1M (Appendix

it. So worldwide,

at approximately

in the relative

is at ~$275M.

is considerably

The spending

and in 1991

consideration.

in real year

it has been

Year

the amount

the energy

Discussions

is probably

decreasing,

considered

are much

technology

the gains

for space

the value

FUNDING

the 70’s.

personnel

to have

In more

reduced,

research

although

probably

bind of

at zero,

funding.

$250_

greater,

SPACE

$1oo_

half of

values.

appear

LEVEL

$200 _

Shown

dollars

$5o _

United

States

10.3.2

began

during

Soviet

recent

reveal

space

fusion

under

10-10

(._ (.- .o_

surge

years

Even

term,

lacks

1980

1955

have

least

FOR

near

later

they

with

The

that

any

the

not

did

A).

$150

o—

that

that,

level

there

space

10.3.3

future?

funding

FUSION

BENEFIT

of several

reactor of

To answer

to maintain

and today,

to develop.

the chemical

the operation

fusion budget

PROBABILITY

FOR SPACE

TERRESTRIAL

use. Compare

the 1990 year

APPLICABILITY

AND TIMELINESS

funding to space

in 1991 due to a declining

the one primary experiment

in DOE, as are all alternate

commenced of

level of $5M at two facilities

for a low level interest

with the gross is very

cost was $11K. time ($48B)

set out In 1916 he requested

$5K for the continuation In comparison

that could have potential the development

the experiments. national little difference

plus several million dollars The experimental

of the complexity that rocket in ~1910 under

for the space program any time of that

of fusion with the simple chemical His experiments

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

—$325M is adequate Princeton experiments. was funded at a total

Is the DOE program likely to yield direct benefits consider in the near

alternate is the FRC which in 1990. The program is being

terminated experiments the task between Dr. Goddard his funding. requested The total between products between the relative funding the very complex FRC fusion reactor

To place perspective, funding fossil energy

which 1980 to 1987 for solar,

fusion Fig. 10.2 (anom87)

funding the relative fusion,

of DOE Civilian R & D Programs (in current dollars).

the years plus the amount

into program and

the national consider

allocated for conservation.

Fig. 10.2. Annual Appropriations

and development

1986

and which

is currently

receiving.

research

Solar/renewables

between

received

sources,

1987 (estimate)

fission,

1988(request)

Conservation

shows

rocket

10-11

levels

$1000

$8OO

level

$400

$200

Year

$800

Fission

Fusion

[] []

Fossil

1982

1984

[]

There is direct

10.0SpaceProgramOperationalEconomicsandProgramImplementation

Fusion, the most technologically demanding of all, and the least developed for practical use, is funded at an integrated level over that time interval below fission which has been demonstrated since 1942, below fossil fuels which have been demonstrated for well over a century, not much higher than solar energy. And this is for the time when fusion was funded at its highest levels!

If we compare fusion research with the funding expended over the years by NASA for chemical propulsion research and development, then one can expect that under the current plan, spin off benefits for NASA’s use cannot begin to be addressed for many decades, if ever, without some miraculous breakthrough. Yet we have immediate applications for it! The funding priority is a direct function of the agency mission.

A grant was made to the National Research Council by the DOE to ”… conduct a study of the priority and pace of magnetic fusion research and development in the context of long - term policy and the factors that should enter into that policy formulation.” The results of the study, chaired by I. L. White, are published in the National Academy Press report entitled “Pacing the U.S. Magnetic Fusion Program,” 1989. relevance to the space fusion energy application as discussed below.

Probably technical anticipated analysis These principles space fusion research need to inquire, “What and projected space program as now needed?”

for addressing of The statement made serves

Let us focus on the NRC activity contained United States

the cost savings cost emerge. of not only initiating

results but of expediting is the terrestrial and will

SPACE FUSION DEVELOPMENTAL RESEARCH PROGRAM

in this study beyond of While

questions we status funding the United States

its progress. fusion research program’s

commercial to the space program.

for an operational is beyond

to be an estimate system?”

Summary” program status.

The NRC study production.

the NRC report, which addresses

the scope of illustrate

question is considered

this study, a few principles

Let us return momentarily

the most viability

it yield the desired

in the “Executive

the latter point.

the importance

ADVANTAGES

OF FUSION

RATIONALE :

As follow-up

The answer

ECONOMIC

to illustrate

dealt with

and study

a detailed

addressed

for space

is, “What

important

10.3.4

electrical

is the

that of

SPACE

energy

results

power

fusion

space

fusion

plans,

10-12

FOR

for

the

are

lost

has

that

The

finds

point

(p 3)

is no

(p 1)

levels

under

fusion

space

further

largely

should

energy

current

that

dollars)

funding

position

proceed

believes

program

because

of a 50

(Chapter

research

domestic

increase,

decrease

narrowed.

objectives

committee

the plan.

in funding

inadequate

Community

the space

management:

since also

its leadership

the near-term

to meet even

in international

longer fusion.

The committee

leader States

percent 1977.

to the European

to the elimination

The NRC report

the United States

As a consequence,

problems perhaps

in constant States

(measured the United

budget As exacerbated,

on magnetic in magnetic

the dominant The United

10.0 Space Program Operational

Economics and Program Implementation

of Energy Office of Fusion Energy has decided to terminate

this prediction made in 1988 appears

cut of $50 million from the magnetic

can for all alternate

be anticipated concepts.

program and economic

programs aimed at developing

a more attractive magnetic

(see our November

to better science

quantify missions.

provided earlier

that sections

a flight show

space mission

its “conventional”

is a tremendous

can be shown.

“Faced with a

the Department

need is shown

and unmanned

1 Unfortunately

its experimental

the importance

to be correct.

fusion reactor

fusion budget

the economic

it will protect

Congressional

The purpose

and mission

(FpaDec 90)

on a space

the manned

unknowingly,

summarizes,

to be real.

the budget

newsletter),

technology.

application,

essentially

enhancing

of NASA

program.”

to focus

enabling

concept.

potential

tokamak

initiating

Instead,

mission

funding

section

energy

payoff

space

fusion

10-13

all of

need

then,

The

that

this

for

is,

for

this

10.4

flight

then,

Later

costs,

report

space

option

fission

energy

mission

consider

MANNED

the costs

equivalent

objectives.

operational

the relative

To examine

Let us assume

of cost benefits,

is not considered

MARS MISSIONS

that either a chemical,

purposes day-to-day

science operational

operational a typical

costs for the launch

to launch the spacecraft,

operational to comprise

in this section, we need to

intense the focus of

so an estimate was made of

fusion mission during

are not clearly propulsion

to accomplish of the magnitude

the comparative costs plus those

and this an option since it

10.0 Space Program Operational Economics and Program Implementation

5-day mission, those values with assumptions

as an energy (NEP) these missions. the discussion

presently system is available either Nuclear Electric Propulsion

exists which can technically meet system requirements, to accomplish

are costs an To provide, the launch costs today in this section costs are evaluated.

capability therefore mission. is not sufficiently mission operational account system into low Earth orbit daily manned mission flight operations.

Mission defined required indication first if we were now to proceed with a Manned Mars Mission. the planetary The Shuttle available, identified.

To transport into LEO, assumed to serve as the launch vehicle for reference purposes. later, other vehicles would probably such, capabilities. is $317M, at averaged mission cost through 1993. as the expected payload mass limit is 27 MT. That normalizes to a launch cost of $9.3M/MT LEO.

The cost of a single Shuttle launch of a payload to low Earth orbit the a number quoted as representing The cost is stated to decrease to $190M The Shuttle’s upper to

in the Mars Excursion Module Earth orbit was 1,000 MT using the following: Earth orbit escape,

energy The 50 MT MEM carried a crew of 4 to the Martian

As discussed this program is current and as

the initial vehicle mass in for

RELATIVE MISSION OPERATIONAL COSTS

and propulsion to perform the

its propellants, necessary

-COSTS TO PLACE SPACE VEHICLES IN LEO

the following three years.

the mass of the Martian

TO LEO AND COSTS

the time of this report

data base as opposed

us with a well defined

chemical dissipation

propulsion at Earth.

-FLIGHT OPERATIONAL COSTS

energy capture

plus those costs

OPERATIONAL

be used, but

to projected

from Mars,

the Shuttle

for capture,

for escape

aerobraking

IN ORBIT

dissipation

spacecraft

propulsion

aerobrake

LAUNCH

provides

SYSTEM

chemical

at Mars’

(Can69),

average

COSTS

energy

(MEM)

10.4.1

10.4.2

(LEO)

10-14

study

orbit

and

for

that

orbit

of 1

costs

power

10.4.3

period.

Economics

COSTS

10.0 Space

FUSION

and Program

LAUNCH

to Earth.

Implementation

in Section

exploration

references,

POWERED

2.0, sends

launch cost,

for a 30-day

cost scenario

Program Operational

that a specific

OPERATIONAL

from a Martian

below assumes

to launch costs.

it was 230 days.

a 61 MT payload

the costs to conduct

to Mars and returns

energy a minimal

a Manned Mars Mission,

is shown in Table 10-1.

is $11,840M for the launch operational

the Mars vehicle including

system is available is now factored

of the MEM in this fusion mission example

This mission, which was the one analyzed

and is on orbit for multiple mission into the Manned Mars Mission cost

The flight operations kW/kg fusion propulsion use. The fusion launch cost

equation. 133 MT payload equivalent summary and performance used in the generation

a The mass is 72 MT (133-61 MT). A cost that were

into LEO alone, plus the additional the Mars trip’s The flight was 160 days;

for number fuel and oxidizer, time for one of the mission’s windows for the return trip,

surface that quantity trips. At today’s orbit consumables comparison Mars using aerobraking

To place surface of mass into Earth orbit using the Shuttle requires a minimum of 37 costs to the by to

powered Manned Mars Mission which of

time to the less than the 1,041 MT

Consider the round trip flight

powered substantially recommended

fusion vehicle’s mass placed in Earth orbit

round trip times, reduces

212 days for fusion

such as 160 days are possible,

of this table are discussed

time. While faster

ROUND TRIP TIME, DAYS

level of ~400 MT.

CHEMICAL PROPULSION

the 212 day flight

in the text below.

based on today’s

NUMBER OF SHUTTLE

Manned Mars Mission

SYSTEM MASS, MT

FLIGHT OPERATIONS

time, exclusive

the Mars visit

OUTBOUND/INBOUND

is significantly

Assumptions

_pl FUSION

FUSION

NA - not available

(MEM, Can69).

the initial

PROPELLANT

PROPULSION

PARAMETER

MASS, MT

MASS, MT

comparisons

requires

LAUNCHES

PAYLOAD

propulsion

SHUTTLE

VEHICLE

MISSION

LAUNCH

10-15

chemical

between

COSTS,

INITIAL

TOTAL

TABLE

That

MASS,

133/61

11,840

fusion

1,000

3,520

1,920

10-1.

Cost

($M)

<90

and

215

402

175

182

apl

for

LEO

FUEL

fusion

10.4.5

10.4.4

PLANT

COSTS

FUSION

POWER

SYSTEM

Because

assumes

propulsion

PROPULSION

The operational

that a reusable

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

initial vehicle mass required for the 160-day trip while the 400 MT mass allows a reasonably fast trip.

For the 400 MT initial vehicle mass mission: the propulsion system mass is 94 MT; the payload comprises 133 MT; and the propulsive energy mass for transporting a vehicle to Mars and returning it to Earth LEO for this mission is 175 MT.

system has been This study costs to place it there are small on a per stationed in LEO. Three Shuttle launches are required to place the 94 MT fusion mission basis. vehicle mass into Earth orbit. Assume a reuse life of 20 missions. The single Manned Mars Mission portion of the operational cost to place the fusion vehicle into LEO is then $37M.

the specific all of to be liquid per kilogram of 3He. The power Mars within 6 months, W-years, assuming 133 MT out-bound efficient fuel. The helium-3 kg deuterium mass

is 19 the Mars vehicle to is 145 MW or 72.5 sized to a 70% is 5.45 kg for a 50-50 mixture of 3.7 to LEO. The remaining by the Shuttle to LEO from an Earth based

In addition to the launch costs, an approximation fusion complete the operations cost comparison. was not available updating

costs to fly the vehicle to and from Mars is required to information for

facility. propulsion mass plus the 133 MT payload mass. mission

orbit, baseline. While other there are the developmental and operational savings,

fusion is 175 MT propellant the 212-day

costs launch vehicles costs to be included

could reduce the number of plus the additional

if more definitive cost information becomes available.

a 1 kW/kg propulsion and 61 MT in-bound

impulse the propellant mass

But there to the fusion system.

system to perform the Manned Mars Mission

so estimates were made which are clearly

required to propel in Section 2.0,

those would also be of similar percentage

for 9.15 kg - will be a diluent,

to LEO for a 1 kW/kg specific

of the daily manned space

system and a Mars vehicle

except The D-3He

The total mass transported

Current operational cost

flights, equipment

or $2,200M as launch

from the moon directly

the mass of helium-3,

MW-year and from

average, assumed

as a comparative

Shuttle larger

payload mass.

uses 7 Shuttle

OPERATIONAL

by the larger

If we assume

using today’s

is transmitted

as discussed

requirement

performance

operational

ooerational

propulsion,

and flight

is brought

hydrogen.

identified

launches,

are any

of merit

seconds

required

incurred

FLIGHT

is low,

COSTS

reactor,

vehicle.

mission

12,000

energy

benefit

10.4.6

power

fusion

10-16

figure

costs

For

costs

for a

which

factor,

simply

Safety

in flight

factored

savings,

selected

because

although

services,

contractor

operations

operational

the launch

the support

for example,

enhancement

into account.

future space

in comparison

role and cost

the impact of

The difference

to a is is

to be supported

can be expected

and civil servants,

are not as large

cost number

need to be factored

the daily That

personnel. and all

by SSF support was used.

that a staff of 500 persons,

the flight at a cost of $120,000

for personnel for salaries

of $60,000,000 flight

of cost advantage,

these into the mission’s

advantages into the operational

cost of $50M per year (That mission support

10.0 Space Program Operational Economics and Program Implementation

by comparison. the larger mass permitted

Consider, support total cost $250K/day assumed facilities,

time savings is not as great as for costs

by the Space Station for a Mars mission for the

per person per year. That amounts per year;

Manned Mars Mission Freedom (SSF), an arbitrarily dedicated Space Station is not yet defined.)

services support of direct to double when the costs for equipment Because etc., are taken

fusion on mission flight the and other by fusion were are major cost powered

From purely the flight operational total science not program gain considerations equation. vehicles missions assume that

For the MEM chemical propulsion mission, mission is $182M as calculated

then Manned Mars mission (Table 10-2):

the operational cost to conduct assumptions;

time for missions with fusion

Mars flight control personnel operational

for mission (arbitrarily assumed value)

for flight operations (assumed equal

is 390 - 212 = 178 days.

Space Station flight support

for a manned Mars mission.

TABLE 10-2. Operational

using the chemical

Total operating costs

using the above

are representative

the fusion,

support personnel

PROPULSION

OPERATIONS

the following

Support cost

Costs per day

cost summary

CHEMICAL

to the flight

operations

VERSUS

FUSION

FLIGHT

Let us

10.4.7

SS0M

fusion

10-17

for a

$170M

costs

$0.5M

costs)

flight

$60M

costs

the

for

cargo

vehicle

greater

analysis

between

is much

indicates.

difference

a manned

as compared

vehicle, which

of an unspecified

to the same for fusion:

comparisons, than

had transported analog)

and the ascent The MEM’s

FUSION … $2,219M + $106M + $37M = $2,362M.

(i.e., mass plus the MEM,

the actual the $9,659M amount

CHEMICAL… $11,840M + $182M = $12,022M

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

For normalized mission missions mission Command Module lander, Earth.

$106M. Thus, the operational cost to launch the Mars mission’s flight systems plus mission flight support using chemical propulsion is:

Other factored evaluations spacecraft that system operation. With the additional fusion greater Hence, accommodate other providing powered for additional monitoring instead to reflect

study was 72 MT. Unfortunately the trans-Martian/Earth for module. it is believed Mars system’s fusion vehicle’s

thereby fusion costs, an allowance in-flight for A cost credit should be given

flight crew, permitting remote More massive (or moons) more a larger

identify the payload mass reentry of the two Earth- the chemical

to remain on the Martian surface importantly, to Earth,

Larger the accomplishment science to serve massive Martian

these two The MEM the Apollo the Martian to this

to permit spacecraft maintenance be accomplished

did not and Earth Atmospheric the performance

dramatically and 61 MT return payload masses.

the flight crew to more readily as well as

functions on the ground, the more massive

only 136 kg of soil sample for

of high specific also must systems.

extensive that otherwise would

crew quarters if we compare equivalent

in comparative for control

power be accounted design

energy a system compatible

fusion such the flight the of

cost would 133 MT outbound

outposts. Most can be returned

vehicle masses operational

crew will have maximum control

vehicle, the spacecraft

the operational not was

personnel system status.

in determining control

total mass was only 50 MT.

can transport per

of space is to provide

payloads as Martian

systems which were not

increase when compared

science soil sample

payload mass capability

of the fusion propulsion

Therefore, flight

The MEM equivalent

with fully automated

into the spacecraft.

payload masses,

can be designed

of more science

fusion powered

“unit mission.”

the spacecraft

the autonomy.

for enhanced

the contractor

a significantly

representing

advantages

and flight

spacecraft

significant

autonomy

additional

into the

functions

on-board

objective

equation

included

vehicle.

in-flight

ground

returns

to the

space

10-18

using

then

over

One

cost

that

But

results

launch

station

~1970,

vehicle

fraction

10.4.7.1

vehicle’s

in order

retention

payloads

important

approach

LAUNCH

necessary

VEHICLES

The space

Thus, prior

and retrieve

ALTERNATE

to proceeding,

and in general

been designed

to space flight.

to its construction,

in a mass penalty.

vehicle was deemed

allowance increases

reusable of NASA.

vehicle was considered

launch A manned

than to use the throw-away

necessary for a reusable

a to carry out to

for from ~1+% to ~5%.

since but to orbit and to travel

10.0SpaceProgramOperationalEconomicsandProgramImplementation

to transport a cheaper means rather necessary

a very costly approach.

operational flexibility, expendable payload, making mass improvement

the means to reduce the costs to orbit have been on-going had originally

The flight of man, while offering mission If we were to redesign and use the current Orbiter’s

Examination of the mid-1960’s. prior back and forth was considered Saturn V or S-1B vehicles new manned the mission deploy

variety of geologic conditions on the Martian surface. A more favorable science mass returned per mission cost value is achieved. These added advantages have not been factored into the cost benefit equation.

It must be remembered that reduce the costs to orbit of designing expendables, transportation vehicles expensive requirements whatever were made to solicit and use “airline-like” Advanced were used. vehicles, possible The Shuttle at years.

If a 10 kW/kg mission cost for the launch of consumables would decline to the expenditure of The Shuttle’s payload capability is limited to 27 MT. a single Shuttle launch. i.e., 23 MT, could be launched into LEO to perform Sufficient the 212-day mission. ,_v energy in that case is only $357M (which includes the prorated allowance for the launch of the reduction from the $2,200M value for a 1 propulsion

in view of study’s higher performance fission or fusion. Many serious to reduce Shuttle to existing technologies

for the Shuttle design was to by to replace the space from new large Going to space is the

it the large payload mass in low Earth orbit.

this through the source of energy, whether

large expendable The Shuttle was designed as part of

the Shuttle as an as orbital mass then the payload ~4-fold

or smaller, cost the history. emphasis

have to be closely examined rationale

kW/kg propulsion system (when referenced to the Shuttle

launch rate would have taken approximately

propulsion, efforts costs.

namely, fewer to more quickly

the original the expensive

launch cost for the mission’s

of whether infrastructure.

reactor can be developed,

there will be one significant

the Mars mission, making

technologies Clearly,

procedures approaches

launches to assemble

in the payload delivery

OF HIGH SPECIFIC

the reusable manned

to the large launch

the same 212-day

to low Earth orbit

the main engines,

fusion propellant,

So any projected

its demonstrated

launch vehicles

on space

launch costs).

ADVANTAGES

are required

a significant

the Saturn

represents

advantage

reductions

The total

capability.

and cost

reduction

rationale

reducing

POWER

system),

vehicle.

specific

power

10.4.8

10-19

class

That

The

the

for

cost

Refer

10.4.9

energy,

system.

Payload

program

system’s

research

FUTURE

efficiency

OPTIONS

to launch

at a total

regardless

throughout

investment

the overall

FOR THE

report, power

the 5 launches

to the program.

from high specific

launch and mission

costs are minimized.

system. redesigns

result in Section

this study specific

It is high risk but extremely

in substantial 2.0.

in increasing funding

high gain research technology.

Because to save to the

higher margins cost

the research is the best up-front

required the space propulsion

operational the 133 MT payload,

As iterated the propulsion possible.

that we wi/I need to find a new means of doing business

power propulsion of safety and reduced savings

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

factors which impact of payloads which are real, but difficult

There are other very significant costs in the design and development that also benefit quantify, of the greater weight will discussions

flight operations cost is estimated at $90M for the half year trip time. Hence, we cost of only $440M, are now looking cost plus a constant factor is high, and operational

is to LEO, a new flight operational systems launch demands Dlaced on those LEO bound mandatory. qhemical systems. A higher probability of achieving public support for frequent missions to Mars can be anticipated where the trip costs to place reduced. We the Martian vehicle and consumables can anticipate in support of settlement. systems, for

in space, or system and the universe wi/I not be payloads to Earth orbit systems will never be cheap due to the physics To reduce launch costs using the chemical propulsion

propulsion change in approach of the nature needed is not

It is c/ear the goa/ of exp/oration achieved, using the current and chemistry involved.

round trip missions to be required once or twice annually

to transport payloads reduce

like fusion, future missions.

The use of high specific

into LEO are significantly

anticipated to be quick.

so/e/y on economic

The development

is a fundamental

Transmitting

technology

WQ must

the so/ar

orooulsion

approach

however,

systems,

of these

grounds.

power

space

10-20

for

one

flight

upon

10.4.10

braking,

FLIGHT

to be in

exposure

unmanned

statements

maneuvers

Acceptable

aerobraking

the shorter

time. With

from galactic

ADVANTAGES

of details.

times. payload

to place accurate

CREW SAFETY

narrow band width.

of a full scale craft,

some the is

is based options.

as a direct consequence

is for a totally propulsive

flight The heavier

stated ray background

non quantitative radiation

can be expected a precursor

flares. Whereas the preference

from soiar penalty of shorter

of additional for shielding less mission

flares more than with trips which

10.0 Space ProgramOperational Economics and Program Implementation

a course of action. rate, etc.) on an entry veh!cle Hence, given the option,

cost values on flight crew safety, are obvious. As cosmic

The there errors or errors in aerodynamic of a very

preference are no abort properties Without the risk resulting operational

before, exposure to Appendix Refer capability makes readily chemical lessen the are retro of

for protection penalty with performance Further, we have the advantage to solar of exposure the chemical system, in lieu of aerobraking. aerobraking

While it is not possible positive, integrated reduced B for a discussion the weight achievable propulsion. probability required maneuver response navigational the domain demonstration high. With propulsive change heating less severe. retrograde maneuvers fission system will be safer, without refer it will probably

Obviously, hardware greatest space toward missions missions. fusion The US astronaut of the Skylab Program.

is in a direction in LEO first as precursor to complete. The time. flight of longer time by virtue now, we could proceed without

from uncertainties exist (drag loads, heating, are

with The to qualify man for 1 to 2 years of

not be necessary would total mission cost will be greater lower

in lieu of aerobraking. requiring to Fig. 2.4.

impact is used since fewer Shuttle missions

Experiment, fusion energy capability than $600M.

the requirement plan for Manned Mars Missions

program activities The savings shield.

that in that case is obviously

powered Mars mission has already

those alternate space example

In addition environmental Earth’s energy

From this perspective a precursor

can be accomplished been qualified

program unnecessary of

such savings are the costs to develop AI,

propulsive the nuclear mission

Further, mass will not be as critical,

using retrograde the preference

are associated savings.

enormous. the Aeroassist

by fusion will add to NASA’s

That program can be expected

propulsive is to conduct

in 3 months than that

to the Moon and extended

longer Another Flight

times. is the heat

If fusion were available

require the qualification

to flight crew safety,

to take ~15 years

DEVELOPMENTAL

The environmental

the less of

is the elimination

cost hardware.

developmental

using D-3He

demonstration

to continually

costs which

for obtaining

are required.

is enhanced

for example,

The current

Furthermore,

any made

the use of

the Earth’s

be cheaper

of man for

experiment,

is reduced

parameters

A current

exposures

permitting

Offsetting

MISSION

durations

currently

because

existed.

COSTS

10.4.11

will be

braking

options

design

travel.

safety

10-21

flight

That

if a

too;

for

under

COSTS

FISSION

aerobrake

10.4.12

propulsion

high thrust

OPERATIONAL

of reduce

some the MEM

could costs of

class operational

the NERVA chemical

Fission circumstances

The mass of propellant saved over

class by reductions in the number of Shuttle launches.

it requires an additional For more massive payloads,

10.0SpaceProgramOperationalEconomicsand ProgramImplementation

and the costs to obtain 3He from the Moon. Note, too, that both of those have cost savings advantages - reduced flight operational costs as discussed in the case of AI operational efficiencies and from the sale of 3He for Earth based fusion powered reactors.

To prove this, that of approach was 250 MT - 9 Shuttle flights or used a hybrid propulsion mix that was comprised of: capture braking at Mars’ An all costs by $1B to be delivered to Earth is impulse of fission The MEM to

payload we only need to refer to Fig. 2.4. chemical propulsion-aerobraking $1.7B. That approach nuclear propulsion for Earth orbit escape, orbit, and chemical propulsion Mars orbit escape, and Earth aerobraking. fission NERVA type nuclear system increased since orbit. provide more significant benefits over chemical systems. expected Rockwell study team used a lower value of specific impulse, 800 seconds, ultimately allow some conservation demonstrated are being looked at now, but some degree of caution must be exercised before we can rely to implement demonstration.

for a In Section 2.0, variety of missions. study evaluation process for the comparative evaluations of a constant and consistent set of input data for multiple science missions, namely, of return vehicles transporting 20 MT payloads to its science target(s) and sample and returning and propellant study would be to conduct a similar distances, as well as trip times. A follow-up payload masses, analysis which considers mission parameters as well as both heavier and lighter which would better define the capabilities than those the lower return targets other these returned to Earth should also be studied as an option. mission analyses would include evaluations of the transport of large science laboratory masses to a Martian colony from other locations in the solar system. Mars in-situ production of propellants become a reality.

testing which by 1972 Higher values up to 1000 seconds

The mass of the initial vehicle upon target mass

this study examined a single science payload mass (20 MT)

That single payload mass provided a normalized

10 MT payloads varied

to Earth. depending

100 MT of propellant

as a major science

the higher specific

Different payload

the performance

limits of fusion.

the operational

850 seconds.

For example,

could serve

for alternate

in 1967-68

irrevocable

differences

on these

MISSIONS

SCIENCE

provided

numbers

planning

outpost

loaded

base,

10-22

prior

10.5

that

and

for

from

and,

That

over

AND

time.

costs

10.5.1

USING

sample

FUSION

is flown

payload

RETURN

ENERGY

SCIENCE

SAVINGS

to Jupiter

EXAMPLES

In the Galileo

unlike Galileo,

IMPROVEMENTS

Europa since

years mission

reduces are

in 1.56 those

1 kW/kg payload

propulsion to Jupiter

operational $~100M

time. flight operational

10.0 Space Program Operational

Program a 0.44 MT science

and fabrication equal

6-year mission available were

power a 20 MT total

system yielding science

Economics and Program Implementation

developmental are approximately

be able to return a 10 MT payload with a soil

If a fusion flight today, we could send

are required to perform the 1.56-year 1 kW/kg having

243 MT of propellants power

the program staff one year or greater

costs for a typical operational

system - but with one to two orders of

gain in payload time by a factor

class by using fusion

for one Galileo the added

A missed launch opportunity

for the period of time until

LEO would be comparable

then the launch costs to

be pointed requires

arises, to $200M,

by $450M The

costs NASA significantly

that have been faced

magnitude in total

and multiple missions

like the one proposed

and conduct multiple

spacecraft, a using

that out additional

is to load fully one

It should capability

spacecraft costs

mass plus a sample

If we could develop

energy systems,

payload and

A cost comparison

launch opportunity

costs annually.

delivery of four.

upon the mission.

That can amount

mission, level

launch windows

target missions.

overall mission

and a reduction

the achievement

program being

is that multiple

to our situation

class mission.

of this greatly

to carry over

with chemical

to a chemical

of a Magellan

in the 1980’s

of below.

are possible.

and schedule

as a concept

one Shuttle

in launching

performance.

as discussed

to the flight

The Galileo

and earlier.

performance

and nature

consideration

of enlarged

a 10 kW/kg

Or contrary

is proposed

deployment

or greater,

the scope

operational

the fusion

propulsion

this work.

spacecraft

is beyond

advantage

propellant

depending

enhanced

the flight

capability

spacecraft

the time

proposed

available.

the next

attractive

pressures

missions

in space

a single

planetary

powered

delayed.

between

objective

reduces

concept

mission

impacts

mission

flexibility

system,

is now

payload

Another

system

feature,

vehicle

orbited

Galileo

specific

launch

higher

option

fusion

further

return

mass.

saved

fusion

using

10-23

upon

flight.

large

flight

here

and

The

For

are

the

for

9 %

That

30 %

83 %

100 %

results.

0.44 MT

payload

0.335 MT

0.103 MT

0.938 MT

1.138 MT

inefficiency

Orbiter mass

is apparent

is illustrated

a substantial

Probe mass *

of science

science missions,

Residual Orbiter mass

Usable propulsion mass

technology on-board.

Total science instruments mass

Orbiter science instruments mass

probe is listed as “science” mass although

TABLE 10-3. Galileo vehicle mass apportionments.

the mass of current carried

from an in relation to in

10.0 Space Program Operational Economics and Program Implementation

inefficiency science spacecraft That

The entire contains only 0.028 MT for science instruments.

In the manner which we now perform space payload science mass inefficiency examination the actual Table 10-3 below (Yea85)

Significant missions. only a very small additional from 3 to 6 when the distance target. that To unreasonable of science mass mass chemical greater mass samples of multiple Efficiency solar gravity, integrated perhaps Solar System Mission

structure, to support Galileo science. The Probe’s science mass efficiency would obviously not be altered by the presence of fusion energy.

that targets is as great as one AU per not be for e,II

the Jovian Probe is unaffected of a more massive power system.

the science using from trade. reduced (and Planetary

The mass of except be flown on a high specific

is now possible benefits in the cost of

targeting gained by multiple if proper

extrapolate to expect more extensive

in Section 2.0 illustrates the number

time is needed between data

This Multiple could be performed

instrument to the total fraction

system probe which could

by targeting is selected).

The Multiple Asteroid Mission discussed

by the propulsion overall

returned to Earth has not been factored

asteroids to the planetary

fractions, mass. beyond

(greater mass) science coverage

the outer olanets in less fliaht

science is to increase

than 10 years with samples

time and with the added

mass spacecraft

per singular mission

of the outer planets

it actually is the

powered missions

for the allowance

heat shield, power,

is that efficiency

back at Earth.

from multiple

instrumentation

The important

The objective

like Galileo.

etc. necessary

The remainder

is obtained

substantially

to increase

by phasing

advantages

the typical

of oreater

propulsion

30% that

Additional

as space

(MPSSM)

economic

economy

targeting

telemetry,

payload

benefits

delivery

mission

defined

moons,

in less

it will

timing

10-24

result

point

too,

the

cost

10.6

taking

targets,

analysis

systems

in favor

is better

chemical

on-board

payloads

trajectory

LOOKING

respective

spacecraft

developed

of a is It

propulsion.

the fusion

instruments

FORWARD

consideration.

is to employ

target planets,

using chemical

the high specific

in lieu of mass for

in space to optimally

propulsion. relying

vehicle along an arbitrary

payload mass for science

space to their is it

involving directly it

powered are launched

is the subject study.

solely, to an optimal

individual complex presented

to the planets to target

but to target or whether

is gained by providing on-board

trajectory propulsion maneuvering

10.0 Space Program Operational Economics and Program Implementation

to their objective-trajectory-mission concept

science science here as a mission study

Whether upon the fusion the deploy to transition

approach as a mobile launch platform from which spacecraft

The fusion mission scenarios trades missions. decreases reactors

A new, alternate mission vehicle individual cost optimal spacecraft, fusion powered science

Some study. the the distant small, the large utility power utility power plants, fusion reactor advanced fusion can serve an even wider space role.

decreases at large inert mass which are not known to scale downward.

to favor range. to achieve If that development

the large centralized The several megawatt and is a subject

in this least not until The to

appear which in the low gigawatt feat technical

With because, as devices of

MIGMA - colliding size reactors

masses, time, we consider

typically is a more difficult

in this report show very favorable cost

ion beams are not believed

was given to the topic of smaller

to be of great

reactor area is not anticipated,

consideration Research

energy fusion fusion

can be achieved,

several megawatt

is an approach.

the advantage

in this small

the present

the design

in payload

for space.

companies

research

systems

devices

interest

future.

power

of of

fusion

10-25

flying

high

for

For

10.7

AND

COST

toward

“detunes”

SUMMARY

SUGGESTED

INFERENCES

for exceeding

cost numbers

ADVANTAGES

OPERATIONAL

:!!i!test :!:gai

study evaluation

pace scienceland

and experimental

with the potential

DEVELOPMENTAL

phase, any specific

this very preliminary

and Program Implementation

payload mass variation

used above are straight

10.0 Space Program Operational Economics

The assumptions a significant

trend of cost savings sensitivities.

resu!ts;i commensurate space explorationi

be challenged. and point power cost penalty developing of Shuttle laws of physics, source. chemical be great implementation be expected of $10B.

circle NASA than is possible with the use of high specific report, additional mission iterate

The developmental/operational systems can on the order the chemical

verify Needed and test verifications, produce meaningful, energy

There is the option to reduce the number to the the same energy

We can gain some systems, as will be the performance

The cost to just maintain which NASA now spends, looking approach,

program_ will realistic, the or cost in a timely

for NASA’s limited the high energy

fusion. of are the fusion or, tangible

and use the current is estimated forward

system using more massive for fusion powered spacecraft.

lift chemical billions of dollars, Furthermore,

future. in the not very distant

relevant in other words, activities

forward, well defined, High specific

are essential become achievement

there is less of a of

reductions, consumption penalty.

propulsion $500M per year.

cost the total energy

propulsion perhaps for

chemical at approximately

and science future, making

have been known for some time.

payload weight propulsion

results in the field of high specific

allotments. launch vehicles

but using the low performance

for space missions will always

power energy studies

This is a vicious

costs for such new heavy

looking To to

that yield fusion hardware

only to a low propulsion

and safety. That

which can be attributed

and power applications

heavy launches.

for space propulsion

requiring study.

Space exoloration

are undiminished

to be expensive,

are not needed

power systems,

to high specific

the advantages

by repackaging

and power

is now under

flight systems

vehicles will

High specific

computations,

requirements,

Any mission

experiments,

and a less

lift chemical

The results

into similar

technology,

conversion.

the theme

demanding

programs

analytical

capability

however,

technical

translate

devices.

benefits

savings

forward

instead

leading

without

energy

launch

power

10-26

That

can

this

is,

void

fusion

energy

Economics

system.

10.0 Space

mission

time for

and Program

Implementation

equivalent

imoossible

reasonably

technology

capabilities

anticipated.

high specific

Program Operational

fusion can

the development

power propulsion

ticket per person,

them unattractive.

In addition, propulsion

between requirements

or with a sufficiently Yet

low Dayload mass capability is long.

effective manner to make A technology and NASA’s The operational cost savings between a Manned Mars Mission using the chemical compared with one having a high propulsion systems of today’s technology specific power of 1 kW/kg is on the order of $9B per mission, or a savings of about $2B per round trip flight for a four person flight based on the mass of returned Martian soil sample using a today’s costs. less than with fusion or any system is substantially chemical

That decision would allow NASA to set capabilities fusion be required Considerable that NASA is therefore order savings the low level of be expected ever. As a 10% investment

budgeting develop impulse energy which technology. from the difference between of 1 kW/kg. exploration very small source for achieving level of resources

is to system of a minimum of 1 kW/kg and high specific a superior level

In leveraging round a fusion report, would save over $9B in operational

propulsion the savings just one Manned Mars Mission power

In in this costs for one Manned Mars Mission

it now in With possible. the DOE program cannot

a fusion propulsion of 5x103 to 106 seconds. system represents is now designed

if on the future, a minimum of $50M to $100M annual

fusion program priorities those mission these

Fusion energy level of specific power.

science

and even the future of NASA’s

additional it realistic that

an investment to only maintain

fusion of high specific

gains space missions,

along with the requirements.

important the funding

energy is “What will

program for many decades,

for and systems

chemical of 10% of

to meet to develop

commence the at

programs investment.

That 10% value ($50M)

The $100M represents

to be of direct benefit

systems, research

cost allocated

system performance

provides power

a topic of Sections

powered manned

having a specific

for a new start,

provide NASA?”

the amortization

is very clear.

as envisioned

in operational

the objective

The question

to the space

as the most

The costing

be allocated

the current

13 and 14.

the current

of 10% of

the future

to realize

time will

to develop

spacecraft,

technology

summary,

propulsion

Amortized

for fusion

leveraged

numbers,

research,

of which

chemical

systems

appears

earliest

funding

against

power.

should

power

fusion

10-27

costs

then,

is a

date

and

that

all

for

and

tens

power.

energy

reactor

specific

amount

Actually,

system’s

research

As shown,

parameters

of Magnetic

that NASA’s

on terrestrial

compactness,

to the extent

The terrestrial

the desirability

Fusion Energy

for high specific

plus science

for space programs.

the capability.

trades were recognized

by the Senior Committee

to many opportunity

that a space fusion research

of and the need to accomplish

to address fusion energy

conversion on Environmental,

can it provides return

for of dollars rapid, more

program be structured of

if a more timely application of paramount

these missions savings, extensive

10.0SpaceProgramOperationalEconomicsandProgramImplementation

at least not critically Any major developments from NASA.

the is is the importance program is not as mass are flight programs power systems will have to

It is important unique space related to be realized propulsion sensitive, affected. originate more systems Safety, and Economic Aspects 51):

In addition, alone, considerably more for an equivalent performance mission! six planetary sample return missions were considered in Section 2.0. The of savings billions a more

The design benefits for compactness which as a result, ease maintenance, advanced

One good example pertains difference power. A committee density reactors. stated that

to high mass density), reduces, and may … 3.

but not cost of power core, of COE to plasma performance,

in the National Another (Mil87) is a limited for

That space. Research example energy restart

also presented Fusion Power. where

characteristics fusion COE [cost

of electricity] limited the fusion

grids are available a minimal

level of difference on Advanced

requirement is specific high power-

important are as follows:

and space program reactor design

power density 100 kWe/tonne.

in 1984 by the DOE to consider

The report on the committee’s

is still an order of magnitude

funding was not provided

Committee start

(including the capital

be given to improving

of to relative

limit. On the ground,

level systems…

at a minimum target

and recommendations

below the required

network requires

the recommended

fusion (Dav85)

storage power.

power density

in the reactor

on reductions

the sensitivity

to accomplish

is the space

is the same

was charged

… increased

requirement,

As a third

(ESECOM)

(Ho188, p

conversion

particularly

the mass

assurance

of safety

the most

emphasis

capability

terrestrial

example,

Council’s

systems,

radiation

high

potential

reduces

findings

offering

energy

should

aiming

space

tasks.

10-28

target

there

That

But

for

the

are

not.

Ash

The

with

high

heat

That

over,

differ

other

times

Other

which

fourth

space

fusion

needs

in the

effects

factors

energy

is that

include

budget.

vacuum

disposal

program

voltages

rejection

priorities.

will pay

are two

terrestrial

obviously

produced

simplicity.

operation,

availability

is proven

production

concerned

difference,

to reduce

conclusion

accomplish

conversion;

approaches

applications

and space

experiments

To present

applications.

commencing

itself many

requirements,

and mission

but a space

the alternate

by the DOE

vehicle mass

plan to delete

with the FY91

to be initiated

and for operational

two differences.

and Program Implementation

10.0 Space Program Operational Economics

10-29

11.1

11.0

each.

Surely

OORT

LONG

years,

SPACE

CLOUD

calculus

BROAD

ISSUES

presents

enduring

not even

STELLAR

the major

MISSIONS

to address

DURATION

ADVANCED

The United

States was

RESEARCH,

new theories

PHILOSOPHY

for over 300

that will permit

PARTICULARLY

the future generation

one will ask whether

by then, we will have

This section provided

should ever had just

be 300 years from now? Will

only a colony. Where will mankind

issues that arose during the study. Rationale

to have How can we expect

really be given serious attention. been invented.

such After all, 300 years a there and new to pass up the old. and still that will not

With missions endeavors ago, country, still be a civilization? technologies How can we expect reliably? destination gain in man’s knowledge by alternate be achieved

perform reach its the be as a result of a stellar mission that may not already technologies?

Let us address should the gain of knowledge or otherwise performed maybe as high as $100B, depending as high as $100B, when averaged

for the stellar mission would individual of every one without joint about his

annual costs orders of magnitude etc. drugs, mission. one or expected

of a single solely for the benefit of man by providing

These ever undertaking be the most expensive

The science benefit person burdening scientific

it can light the program could budget

On a per year least an order of magnitude

that objective to man’s mutual destruction

the above items. A stellar mission with science

were of 10 billion dollars,

space mission that man is likely to consider

pursuit than funding Although

into the future with so many uncertainties?

and many other questions will certainly

and science the can be

rather to his detriment.

as the objective being

The stellar mission will undoubtedly

basis, less expensive.

no stellar mission cost evaluations

on how the mission is costed.

of science, mission flight

all. Because on Earth,

as a national destined

equipment to underwrite

gained from the technology

Even if it is the $30M

be made an international

it would not be surprising

It must be remembered

that spacecraft,

less than the amount

for quite some time.

spent on intoxicants,

this is a long term,

it be too expensive?

the stellar mission

two year missions.

we pay typically

to be in excess

the imagination

be a welcome

from mission

A cooperative

be pondered

for the sake

the mission,

the financial

the science

this nature.

our current

until so far

$750M for

Considering

the life of

extensively

knowledge

a mission

developed

spacecraft

What will

is a very

a venture

out over

to be at

is trivial,

so long

probably

tobacco,

returned

certainly

hundred

thinking

venture

“active”

endure

nation.

before

Three

major

years

costs

here,

goal,

time!

least

11-1

long

Will

for

11.0 BroadIssues

It is indeed Stellar exploration is the next step beyond solar system exploration. a large one. The distance, times, mass, velocities, and power levels associated with just a simple visit to our next door stellar neighbor are impressive. To arrive there quicker, the energy requirements become staggering, just numbers with which to deal.

galaxy would provide a spiritual unification of unprecedented magnitude. Even if that spiritual unification and international understandings were the sole accomplishment of the mission, then it would have achieved for a comparatively small sum that which large defense budgets and centuries of war have been unable to accomplish.

The stellar mission was structured to provide “real time” flight data, using very high quality telescopes, on a biannual basis. It would be a short time before the stellar spacecraft would be beyond the bounds of the solar system, providing i.e., not subjected to natural influences of the astronomy of interstellar quality - solar system’s physical dynamics. The science would commence being available early, thereby providing a rapid payoff, not restricted to the benefit of a fifteenth generation. Thus, it would be for today’s scientist, as well as those for many generations of succeeding scientists - a gift from the older generations to the young, yet unborn.

Our technological knowledge has become so impressive in the past 300 years, why not wait for later technologies to be theorized, researched, and developed, fusion as for example the next hundred years, and arrive before this first powered machine? That may be the situation, and the same logic can be employed to postpone the trip 50 years from now, 100 years, or however long one may wish to rationalize the delay. But the same situation is valid with most items that one purchases in our personal lives. How many of us turned down the purchase of an automobile at a given time because a better product can be anticipated to arrive later? How many avoided the purchase of 78 rpm records, the mono long playing records, or stereo, awaiting for the development of compact discs? Who refrained from black and white TV to attend only to the purchase of color? The list is lengthy.

The goal of the stellar mission is for man to seek knowledge about his universe. If man is destined to inhabit other solar systems, the time required just to obtain suitable targets is extraordinarily Let us postulate a sufficient improvement in Earth-vicinity sensing systems, such as interferometry, and that they even become advanced beyond our expectations, and that planetary structures to discern habitable planets are discovered within the realm of those postulated missions in Section 2. Immediately following the initial excitement of the discovery we can anticipate the question of life. We will wish to explore and study any biological phenomenon present. Thus, there will be much interest in knowing the physical details of those bodies.

The only way reasonable will be to obtain a microscopic view of the planets by If analysis of the data yields positive results, then a remote sensing spacecraft.

lengthy.

11-2

that

over

in-situ

stellar

value.

unique

science

Because

by man.

advisable

habitation

interstellar

theoretical

expanded.

conversion

exploration

than ever.

discovering

If negative,

time scale

the frontiers

and arriving

given below,

of an unmanned

of space science

is to be retrieved

then the the

11.0 BroadIssues

prior unmanned

were to be experienced

If a mission catastrophe

program will be necessary

is, therefore, a significant

to permit life elsewhere

the capability A precursor

is such that we need to consider

to the question of

these missions will never be quick.

life here on Earth even more precious

future new energy transportation

planet to Earth throughout

rendezvous before any manned

at a habitable data are to be returned

A start for a well planned is essential

as early as possible Certainly program. to commitment

a program will be initiated of answer species

this program will the a after a period of will

Based upon rationale on preparations optimized cost providing mission. flight can be contemplated.

Even without have great stellar mission, continuum. time such as 100 or 200 years, have been enormously

The possibility current improvements why such a mission should will not become more learned or that we cannot do better.

application Man has been involved with the conduct for over thirty years for peaceful the enormous

The energies consider technology Explorer” vehicle will probably pass

antimatter following consumed Even upon proof of principle

propulsion our current inception was over 50 years to the first manned

Thus, original that energy research It is difficult provide our original

technical reason to claim that we to it is instructive

the velocities any quicker fusion at

in the computation effects because to arrive there

(mirror matter) the demonstration to produce

than the “Alpha Centauri the &v of

than fusion The proton-antiproton

needed to pass up the Alpha Centauri Explorer

power will probably that

source that could

technology. is currently energy

The total energy what we look for

the mirror matter of practical

consumption is higher specific

today to make some suppositions

least an order rocket

up in specific fusion.

the new to in 1908.

involved any relativistic

from its of of

in the ratio of 10,000 to 1.

to do better energy.

next improvement

theories would invalidate

did not For a new

history, the future.

or greater, of energy

and offer breakthrough

examine knowledge

in the minds of some

the amount of energy

have to be increased

a century amount

the time to develop

of mass for matter-

using this reaction,

our contemporary

not be attempted.

a 1 to 2 order

science about

the assumptions

it. Dr. Goddard

realistic But

work on liquid

of the quantity

the nature of

the production

fusion energy

are too slow.

of magnitude

is enormous.

new energy

the primary

this study’s

applications.

commenced

2000 year

to harness

is perhaps

trajectories

technology

conversion

individuals

spacecraft

propulsion

to project

limitations

consume

chemical

Basically

reaction,

It is not

provides

in flight.

starcraft

starship

system.

energy,

space

study,

state

11-3

over

step

The

and

this

But

our

the

by:

will

the

are

that

and

that

The

light

With

flight

light,

other

being

There

power

speed

higher

values

curves

2 that

in the

energy

require

exceed

specific

of very

systems

impulse,

increase

is noted

ultimately

in theory

reference

equations

relativistic

confirmed

of motion

to exceed

in particle

spacecraft’s

we require

requirement

accelerators

that would

to changes

experiments.

requirements

high specific

The exhaust

too. power

allow an object

imposed the

11.0 Broad Issues

Ve = g Isp = 107 m/s.

Note propulsion

by physics specific

performance systems

which may be very difficult.

high specific velocity

power is determined

is a limitation Section

(3 x 108 m/s). be constrained

the performance Hence, by the laws of physics.

per cc at a speed technology

only to be invariant

proved mass of mechanics

force “The motion,

Relativity our concept

of alteration He then

as: impressed…”

is estimated of drag

Stated mathematically:

a density upper

upon the definition

remain Actually,

invariant with

(The Mathematical

having be the

1686 assumption.

of 0.9c effects

and its velocity.”

the drag loads

later original

be remembered

as the product

may “invalidate

to the motive

why a current

one will note

law of motion

or momentum,

by Newtonian

into account.

with velocity

theory may

that Newton

and thereby

to from

as rationale

requirements

The energy

of 1 proton

of material

than when

(mv) = m _

the second

from Latin

atmosphere

proportional

that dm/dt

unrestricted

Philosophy,

the speed

mechanics,

of motion

“restrictive”

of a body

the mass

I. Newton,

of Natural

of motion:

of motion,

referenced

knowledge

has been

of motion

with time

His exact

Traversing

elaborates

are taken

in excess

the body

interstellar

incorrectly

are even

compared

statement

translates

Principles

a reason

reference

produced

permitted

literature,

velocities

becomes

a space

revisions

relativity.

changed

theories.

provided

“limiting”

relativity

heating.

theories

quantity

is ever

current”

not for

science

defined

to the

It must

to that

greater

to the

to get

to the

infinite

1686).

theory

stated

value

when

since

state

light.

“The

= 0,

11-4

laws

= m

limit

dm dt

rate

F _

and

due

that

gas

not

the

dv dt

did

for

’

but

the

but

i.e.,

that

case.

fusion

relying

power.

refined

benefit.

specific

refined,

science.

the vast

of energy

likely that

of current

Uncertainty

“restrictive,”

but perhaps

improvements

was therefore

for mankind’s

limiting sense,

in sense.

are well defined,

resulted than

11.0 Broad Issues

in new capabilities

from the utilization

is also a restricting

of has rather

is another example.

the matter-antimatter

Newtonian mechanics

a better understanding

upon the development

term lay in the technology

Based upon those trends,

Heisenberg’s is not it

not vice versa in an expansive

provided theory of new,

or a better grasp of The challenges

costs, a viable space energy

and its attendant it can not become The best

of the nature of gravity will be

vehicle’s than the speculation invalidate

real hope for space transportation and the ability

The sources the binding forces of nucleons mastered

plus the system and the safety source for a very improvements

they will become more “restrictive.” to mankind to enhance fundamental

technology reaction problems show that long period of time. in the near space greater which empirical excluding

the general an upper Quantum mechanics Principle current principles will be invalidated The source by science technology theories.

The fusion challenge. particularly thermal provides reduce the system’s life limiting concerns will be material a solid state propulsion an aneutronic context. developed, flight vehicle, needed times

As widely has been fusion unclassified and is pursued on a world-wide basis without the ownership of any All of the activity is devoted toward resolving the single nation or organization.

to The major if The use of to space fusion in this can be with the for the life that

anyone still be actively used 40 years later. We can make a similar DC-3, but

stresses. does time to a more reasonable age life degradation

The probability that new fundamental theories therefore,

reliability But space regarding and mechanical good evidence.

the current basis. We should, space fusion research.

for 200 to 300-year missions for

of principles may be derived

is an excellent abstinence fatigue

viable and thermal importance

system materials life does exist.

respects, and from spacecraft

instead ~60 years is its use history.

environment The Voyager

the B-52 would ever dreamed

plasma is compatible

already not preordain

its thermal for missions.

involved with the design

one with a sufficiently

A trend of extended

it would the

from an oxidation

the is a lot

a good approach

system becomes

an even greater

DEVELOPMENT

that a suitable

that happening

That assumes

fuel assumes

development

demonstrated

low neutron

environment,

as rationale

OF NASA

high power

and reactor

REACTORS

recognized,

to increase

requirement

operational

particularly

abstention

statement

magnetic

is a very

IN THE

flux that

longevity

in many

FUSION

a good

induced

location

SPACE

ROLES

related,

I doubt

provide

energy

Vehicle

control.

staging

density

having

value.

about

DOE

AND

11-5

11.2

that

real

for

day

any

that

That

fusion

power

safety,

speed,

charter

(SRM),

internal

devices

NASA’s

including

technical

internally

situation,

capability

capabifity

V launch

it assures

production.

” (Anom58).

the Saturn

performance,

its resources

a commercial

developmental

are developed

and efficiency

the technology

11.0 Broad Issues

energy. for

can be established

terrestrial is space

decisions the best

and space vehicles;…

diligently capability,

its energy -the

organization of

of (SSME) etc.

by NASA, not by an outside

in use. and priorities

research relating “system

by the original Space Act of 1958:

its charter, by fusion provides

the largest or These

DOE has been plant

A strong organization to technical

to do so is mandated the usefulness, of

problem for electrical namely,

for proper management comprises

Shuttle’s Main Engines vehicle,

power and aeronautics; some

because A consuming to best service to use fusion

technical like NASA is essential matters.

NASA and the solid energy office. “(2) The of

safety” understanding nature optimizes present implement commercial technology. adopted importantly technology.

energy pursuing powered internally most powerful machines rocket motors conversion The authority improvement aeronautical

Significant therefore research forms attaching program priorities. specific radiation

and helium-3, production requirement that will serve NASA’s to gigawatts built, as opposed space

an inherent of any organization the its needs. Under to its ability energy, fusion for of in fusion

and 1 In the DOE, with all without and NASA’s high are

net energy NASA has the a reactor design and propulsion.

1 The concerns expressed in this section on the importance of NASA initiating a space fusion

the physics than the mainline for a propulsion

system capability of electrical varies

of must for Earth-based

of which is more difficult program’s

power plant’s gigawatt zero of vacuum and

the program priorities development

like the FRC which are applicable to NASA’s space mission.

the two agencies. necessarily

is and most to use the

less) can be The provide

size requirement. gravity

if NASA decides is predicated

and preferably power generation

it will establish possess

to a commercial environment

to demonstrate fuel, D-T.

any developmental

priorities the technical

The DOE program priorities do not

high specific power systems

light weight, designs

program fuel of preference

that is deuterium

application, needed

applications needs

energy alternatives

of energy any

application. But

by NASA, it will

upon the development

between on fusion

and DOE missions

tens of megawatts

require systems

function capacity

program are illustrated

or even terawatts

power, cooled.

a dual output

if a new space

power energy

by the elimination

high specific

The physics

the importance

if sufficiently

the NASA

from small

no longer

operational

importance

differences

the space

of continuing

technology

for space

propulsion

to space

experiments

programs

of space

terrestrial

particular

expertise

the space

experiment

internally

compete

between

strategy

impulse

programs

important

desired

Hence,

alternate

(Fpa90).

energy

NASA

fusion

could

reflect

exist

11-6

has

(or

for

will

the

has

and

thus

11.3

what

plant

result

which

space

fusion

power

These

in the

reactor

in turn

outside

physics

reactor.

not set

LUNAR

realized

Further,

recently

MINING

involved

program

IMPACT

designer

are not

available

The Air

designer.

affecting

emphasis

separately

differences

in another

significant

the fusion

experiment.

approaches

Precedence

in different

The most

fundamental

of a fusion

has design

in Appendix

A. DARPA

to research

as discused

configuration.

for a NASA

not available

is not widely

as an activity

in one design

to the terrestrial

become Force

is that resolve

TO EXTENSIVE

to the spacecraft

with the funding

power options

ENVIRONMENTAL

11.0 Broad Issues

This is a question

has funded MIGMA.

Ref. Bil89 addresses

community necessarily

will has been

resolution the physics

and the effect on astronomy.

design options The commercial

from the Workshop. of dust clouds

raised at the NASA Lunar Helium-3 Workshop which is being

pursued raised there was the creation

community can hardly and concern will be raised over

on an experiment which is now the case.

concerned lunar observatories

the can be anticipated

but questions This is illustrated

to the flight of deuterium or helium-3,

and aspects An international

to burning tritium in the Princeton

basis than To allow the

environmental environmental

land considerations

as the Earth becomes more

international to increase.

as early as one is aware

tritium or any radioactive

Actually D-T which

to oppose TFTR.

it would be appropriate

by opposition

using the advanced

It can be expected

it holds potential

ENVIRONMENTAL

DETERMINATION

INTERNATIONAL

into a reactor.

has placed

DEVELOPMENT

has not been

paper written

as a “system”

EXPERIMENTS

these matters

COMMENCING

ENGINEERING

to commence

of problems,

identification

and water

independent

an isolated

ADVANCED

too distant

REQUISITE

in the not

recognized

INITIATION

experience

has been

NATIONAL

INVOLVED

PRIORITY

this date

IMPACTS

TESTING

PARTIES

a Sierra

BENEFIT

OF AN

VERSUS

benefits,

GAINED

a wider

POWER

masses,

MODEL

earliest

tritium.

FUELS

testing

further.

BEING

as of

future,

rather

There

object

series

FUEL

future

policy

NOW

1 1-7

fuels

than

FOR

fuel.

Club

THE

NET

THE

11.4

11.5

that

fully

D-T

11.7

11.6

THE

FOR

logical

MASS

MISSION

SCIENCE

increases

PAYLOAD

MISSIONS

significant

ADVANCED

TIMELINESS

or decreases

REASONABLE

characteristics.

capability made

11.0 Broad Issues

OF THE STELLAR

will not substantially

step for space science

to consider. is always put

the payload mass’s impact on vehicle size and flight

Any new performance to a full capacity

exploration The length of mission duration of

available, application with a need typically The use of a high specific power and impulse time alter

The 20 MT outbound/10 MT return value assumed in this study represents an educated guess for a desired payload mass to conduct desired future arbitrary The real value should be determined from a group of space science missions. scientists however, existing for even more capability. system desensitizes such that performance

The next stellar exploration. earlier development an early, lengthy, fiscal, initiated development gains that much longer. stellar mission now.

program would thought plan a program in an orderly time is an additive,

the solar system is the time will be be the optimal

out program can be fashion. delaying

beyond is a factor which favors

to optimally time is involved,

Because the developmental

Whatever the science

too early to commence

technical, early

and managerial

the capability.

low funding

approach.

the flight

relatively

planning

A well

is not

Thus,

for a

level

11-8

and

12.1

points

12.0

section

manned

reached

business

essential

payloads

in space

to Mars

economic

Additional

to ensure

associated

exploration.

an “energy

the study’s

summarizes

is absolutely

key conclusions.

from fusion energy

and safety dividend

a space that

planetary to launch

This conclusions

particularly where high energy

The best method shortage”

in the study are discussed within the text.

mi_;;ion. The expense repeatedly

CONCLUSIONS REGARDING HIGH ENERGY SPACE

MISSIONS AND THE FEASIBILITY OF SPACE FUSION ENERGY

for the A new way of doing is required. future of the space program, resides The greatest with the in the manned energy for costs settlement will become too large to perform any more than a token level for of space is to preventing be no initiate “guarantees” from this study’s

The goal of any program is to successfully objectives energy missions stringent oerformance expand

Based upon projected in the terrestrial priorities, energy availability commencement there accomplish. happen.

Highly required a subject which must be stressed

needs, upon the progress made fusion program fusion

for NASA to initiate a program to develop Any

of design on life performance the long lifetimes

space of a space can be no guarantee

future space missions there the results

of years and flown subsequently. including

fusion this effort will be successful,

program now is important the development

its mission the high very reliable

process mechanisms importance

The because to it will not

research system’s influence meeting

demands over the space

Of all type considered

demonstrated known sources

To successfully considered

the program there is a guarantee

for hundreds of energy,

is imtL_ space. for

is projected of

for uncertainty.

and upon the terrestrial

the and their

appear encouraging.

with our now.

and manufacturing

herein will place

very frontiers,

and investigations

scale a high

of understanding

that degree

fusion program,

The importance

this technology.

ri_k. nature

space mission

to successfully

as we in the

will be quick

fusion that

with minimal

be life test

is of utmost

performance.

the upon

is ultimately

But without

accomplish

the most

duration8

program

the to

systems

analysis

it for

positive

fusion’s

system

cannot

results

recent

While

these

since

12-1

12.2

12.3

long

time

that

can

has

12.5

fusion

12.4

energy

use of

its safety

for space

possible,

to whomever

12.0 Conclusions

of role in space.

fusion energy and take advantage

The development States leadership abdicate

If space fusion energy were available for space now, NASA could make very cost effective features.

be theoretically fusion energy has the most attractive properties that will be consistent with meeting the requirements of long life, high reliability, high performance, and high level of safety that is ultimately considered to be necessary. Fusion, then, appears to offer risk approach in initiating a program to perform these the minimal missions. On the other hand, there is a substantial level of technical risk with the timely development of this hardware.

A new class of high energy knowledge man’s enhance space, engineered. The science the use of more massive

prime contender and have accumulated are initiating program funded. image, one showing

Great mission available been missions. fusion will Consequently,

that long time into the future. has been

space missions, which would substantially system and cis-interstellar

developed. been technologies and perception, result.

the work. program and have a good strong

is to be gained but as an ingredient

the are being pursued of a Pygmalion

provide research capability.

in NASA’s to a large degree,

until a very science mission

faster missions, more operational

capability They fusion

energy return realized

and exploration payloads,

energy is reminiscent

The scenario i.e.,

no such high energy mission

benefit from fusion,

energy instead. effect,

which of advanced

the research role.

real or not, can achieve

They have proven their

from the large energy

can be accomplished

by which to finance

It would a strong

To not accomplish

not be developed

release has

is a consideration

the consequence

new international

an active space

can be suitably

no high energy

and enhanced

to the United

is a result of

an advanced,

the perceived

The omission

to the belief

is attributed,

of a as a

established,

requirement

to assume

the wealth

is to The

suggestive

leadership

alternative

neglected

is Japan.

is critical

flexibility,

technical

Because

planning

if space

whether

intense

desires

energy

of his

safety.

fusion

vision

solar

12-2

12.6

12.7

less

that

has

12.0

cost

12.8

using

power

today,

Conclusions

energy

Fusion,

or not,

benefits.

obiective

reflective

however,

launched

its merit.

a Shuttle

it The

developed

conversion

operational

of whether

respectively,

is developed

or negatively,

be over $8B.

device, were

of high specific

at an averaged

power propulsion

If a fusion system,

the role of high specific

and mission between

for the first manned Mars flight

space missions Regardless

power systems nor of

devices at an appropriate

fusion power propulsion

its true importance and safety

is not reflective its economic, mission,

systems. $200 - 300K level over

of NASA’s missions will be severely by the presence

energy system and a fusion system for just one Manned Mars to be is not expected if the mission occurs within the

impacted, or by the The current NASA two years the past to vitality the to our level or any other high

specific would be used to great economic current savings chemical Mission would available next 20 years.

The fv’(ure economics either positively absence investment on high specific NASA’s for NASA. importance future must be recognized with the commitment of of resources

The _ aided by the faster from the integrated launches would enhance benefit over to Earth.

power that advantage greater payload and exploration power.

penalty system, would masses, missions current concept. importance

is the relief reduced Another situations to return greater

safety trip times, Future science of high specific

A trip to Mars could be aborted of D-3He over D-T renders

benefit Significantly operations. to contingent

the development have proven more difficult

is to be paidby that along with the loss of

safety benefits achieve also expected

a high level of safety. to result

Spending and the anticipated

The most significant to cosmic

than anticipated. the greater

The fact than anticipated

system designs constraints

overly fusion reactors

the additional of quicker

features. the availability

commensurate time.

an advanced with

in terms of Droiected dates

those initial mission savings

is being made in spite of

The fusion developmental

for the Earth’s population

flight and ground safety

to respond more quickly

Less severe operational

has been demonstrated

trip times. exposure

and other will

in space from its use.

fusion will perpetually

that steady progress

the design solutions

in transit inherently

of a high specific

rate of spending,

gives confidence

missions would

is the economic

is the capability

to the eventual

be substantially

long distances.

be at a level

The selection

developmental

the absence

interplanetary

The loss of

and simpler

of manned

by virtue

obstacles

optimistic

historical

because

to are

resulted

its true

require

remain

safety

12.10

trend

have

must

rays.

12-3

12.9

the

for

suited

near

reactor

“focused”

viability

logically

(Maxwellian)

all emphasis

driven fusion

looms for

the relatively

approach approach

12.0 Conclusions

be better approaches

Perhaps for producing

to cause the fusion of nucleons.

program has been concepts

far into this study. placed as the

could that design of course, large

exists only at some point to from the results of

best, most practical a more success. That suggests may have merit, provided, an inordinately consume that preferably

12.11 The conclusion that fusion’s feasibility the future is not necessarily subscribed in the terrestrial Practically upon “statistically”

outcome of controlled fusion. For terrestrial use, the question of its economic term fusion funding and priorities, but application which retards terrestrial that economic concern is not applicable to space missions where the performance advantage is so significant that major cost savings are made possible over the other energy sources.

The compensated accomplishing inherently more spacecraft. atmospheric powered launches makes energy

The space system requirements program which DOE pursues power production. As a result, space reactor different

operationally to become endee, vQr_, a large payload mass A reactor designed fractions,

space For commercial design is essential. possible upon capability.

the benefit space vehicle power makes depending power

high energy More A reduction launches

conversion operations produces operationally

costs by the anticipated ambitious

and ICF process does not and power

from the The reduction kind to Earth’s

to cause an entirely by the results

to a high specific from 20% to 70%,

fusion electric that’NASA’s

fusion propulsion and to its

energy in space Fusion

per mission number

can of chemical

from those in the terrestrial

of chemical environment

reductions missions.

tritium not be burned.

large payload mass

yield payloads

and the reactor’s

and is therefore

that quantity

for fraction

it is reasonable

reactor design

are sufficiently

of commercial

developmental

fusion more

differ for

consumption.

requirements

the focusing

are for an

to anticipate

performance

the benefit

is indicated

like Migma

recirculating

be carried

to achieve

established

to evolve,

propulsion

the flight

and that

efficient.

selected

duration

different

process

system.

specific

in the

results

higher

fusion

12.12

12.13

12.14

12-4

per

The

flight

Also,

units.

12.15

space

fusion

power

station

herein.

forward

reactors

demand

and for

powered

operating

for space

to provide

applications

12.0 Conclusions

experiments,

never for

will probably

of commercial

the generation

spin-off for

reactQr space

the mass/power

from the terrestrial

power units typically

designed propulsion

space versus terrestrial.

and the modes of operation

in a straight be a suitable

its intrinsically fusion

differ and aeronautical

large mass, electrical Differently

is a product of the results of the various experiments

reactor although power designed

electrical from space and aeronautical

tokamak reactor, line from the present mainline

fusion not be a direct, program where the

for the different environments learned from one reactor may not necessarily

The space engines simple straight reactors will be designed power. Ground power could be important

due to its low power it could be used as a on the could very well The it. That be applicable to date.

contained extrapolated could output stationary lunar or Martian surface. be required operational the physics to another

Currently, NASA’s 12.a_g_e_is determined economics The rate of funding level, energy which Fusion COE estimates trade since crude oil costs are relatively well known, is a potentially conditions,

For NASA to take advantage civilian high specific not guarantee space use. program experiments advantage Precedence Research alternate NASA initiating is too important research

for a NASA space fusion activity by the Lewis of to fusion fusion

system being available the past and NASA can seize

levels, and power. its i.e., costs of interests. economic price, as is

for program does for fusion upon the

space fusion program is required. systems.

future the goals, for commercial program’s

its space fusion program. to NASA’s

space reactor fusion by the requirements,

commercial with NASA’s a viable

is established are not necessarily

demonstrate low. number,

power the two programs.

research by DOE in 1991

confirms Even if restarted

cancellation the importance

of the terrestrial

future to have an off-again,

The current based

NASA has a requirement

Center’s experiments

needs and requirements.

flight leveraging

and its developmental

since the mid-1950’s.

electrical progress,

later, on-again

synergism between

work accomplished

by the world-wide

Success power

in the terrestrial

The advantage

on international

a high specific

not on space

has been set

is substantial,

the extensive

the terrestrial

even if net

a dedicate_l

units differ.

for space,

compatible

application

terrestrial

program.

research

funding

volatile

energy

cannot

power

fusion

There

12.17

12.16

Thus,

today

12-5

The

but

that,

were

12.18

fusion

today,

safety.

others,

results,

gamma

science

reactors

enabling

because

effecting

relatively

The cost

or cause

this time.

immediate

enhancing

processes,

application,

to missions

12.0 Conclusions

is preferred.

economically

with today’s

demonstrated

is aneutronic,

cost savings,

new missions,

to be possible

of only charged

rays, or X-rays

does not appear

fuel of choice for space

Those space fusion

the generation Neutrons,

trades for space fusion and terrestrial

are strong motivating now.

space increasing are different. consider

from the plants would not be used simply

competitive On the other hand, space fusion,

in the pure For space energy from the particles only as

power commercial not presently price of energy. used for

and fusion factors why NASA should

the they are cheap if available, would be new producing

The f_ion sense, conversion reactor impediments devices because power output D-3He, while it alleviate consideration.

upon theoretical applying is a consequence improved preferred operational sufficiently development

the lower The space D-3He needed for the high performance

good specific is the fuel of preference. does not completely design based

as well to be simplified is more likely to be made a practical

operational fuel cycle. and safety that a D-3He reactor and acceptable

Demonstration to a flight vehicle kW/kg) convert performance

variable ranging from 5x103 to 106 seconds.

for application power to efficiently impulse

Therefore, safety and reasonably

in That and the the the

the higher energies impulse which

of physics, to the development

The confinement one most the

fuel D-T reactors will be achieved

program can take full advantage

for performing is beneficial

but benefits of a practical

preferred to ultimately

reaction will be more difficult

system design which yields

are expected reactor.

is of utmost the plasma

reactQr high specific

by test_ of an engineering

is magnetic best

the neutron Also,

in the design process,

in effect as “ballast.”

as being system

deuterium-helium-3

in the propulsion

first. of are

stellar missions.

system specific

serving of

of simplifications

space missions

as a significant

problem which

and the ability

the engineering

are considered

the technology

first, although

considerations,

considerations

demonstration

into efficient,

its inherently

high specific

confinement

to transport

the vehicle

temperature

engineering

demanding

to achieve

importance

for gains

protective

therefore,

to space

aspects,

involved

remains

scheme

greater

ignition

it as

reactor

energy

satisfy

which,

fusi0n

space

12.19

12.20

make

serve

likely

12-6

The

that

(>1

the

its

life,

and

With

level,

(Field

12.21

status

having

reactor

toroids,

at power

Reversed

and their

as viable.

theoretical

not been

recognition

requirement

the reactor

Configuration)

this provided

developmental

to the status

has physics

power because

Plasma to space

12.0 Conclusions

Other key parameters

the ICF could change

before we can consider

upon NASA to have alternate

aDDroaches advanced but

and considerations potential,

temperature Any of dipole,

program has focused on plasma experiments.

like steady are important having are viable

stability must be demonstrated as a major objective

balance, the other approaches tandem mirrors or

state operation, require a high 13, like to this options

designs chance of meeting the space specfic

of the is the 13. high D-3He can be of regimes this

It is incumbent FRC’s demonstration developmental is too early developed are mandatory. scaled to reactor

requirements. existing greatest FRC Declassification burned. interest approach power analysis/testing. compact approach.

Other conce.ots variety of options practically The NASA Lewis EFBT was terminated explored review of

dependable dependable, scale concerning obviously more expensive less provide development one consideration.

of space applications. before it had been extensively to the intensive

than small experiments, approach costly the cost takes

with regard to understanding are key to the accomplishment

into a satisfactory Scaling (net power)

space laws and plasma configurations

for net power the main DOE approaches.

stability when the design are concerns.

class. can be developed

they are expected fusion

(such as Migma and RACE), although

While these full scale test devices

a large there has been

stellar mission reactors power

because toward instead

exDeriments concept

tend to be large in size.

The most difficult mission

modeling particularly

of them in the context

the the the it be

to space and

It is a viable mission,

and has not been

transport. of

to know whether

that high specific

those considered

for consideration.

by their nature

level or better.

at a 10 kW/kg

energy into

this reactor

no examination

These include

can definitely

herein is the

are available

and backup

confinement

is complex

approaches

an overall

of plasma

to achieve

feasibility.

not Full

Accurate,

provided

exposed

answers

are to

systems

benefits

concept

or not

Hence,

Fusion

safety

12.23

12.24

12.22

when

time,

12-7

and

this

the

The

state

long,

great

class,

years.

power

restart

steady

placed

system

specific

12.23.6

12.23.5

12.23.4

12.23.3

12.23.2

12.23.1

impulse

multiple

perform

high rf

average

systems

seconds

in-space

if higher

electrical

of 10-20

capability

propulsion

or greater

transmitted

MW output

high thrust,

of 10 kW/kg

that mission

on the order

on its space

is mandatory.

are developed

use of D-3He

firing durations

high jet power,

12.0 Conclusions

demands include:

5x104 N at 400,000

of 20 GW or higher

by the stellar mission

the availability be fully

facility could be eliminated.

manufacturing concerns

fuel, is to breed

fusion An option

is to burn semi-catalyzed

tritium in the quantities

or by objectives.

The helium-3,

for space missions

from the plasma.

D-D and remove

that an orbiting

the achievement

more massive

as an option.

the magnitude

implementation

on the order

an enormous

lunar using

light weight,

of significant

consideration

environment.

to enhance

considerably

as adverse

the moon

researched,

on Earth’s

be shifted

the tritium

is needed

for space.

addressed.

necessary.

conversion

particularly

for space

operations

production

reductions

be given

If proven,

efficiency,

feasibility.

Qn orbit

examined

of space

the high

extensive

assembly

planetary

passively

in either

suggests

payloads

electrical

Because

vehicles,

missions

question

lithium-6

required

in flight

duration

carrying

Another

reliable,

designs

science

mission

cooled,

studied

plasma

energy

Tritium

benefit

station

should

impact

All of

obtain

power

where

fusion

space

highly

would

Direct

of 50

which

12.25

12.26

12.27

12.28

those

could

been

have

must

flight

work

12-8

high

long

This

time

3He

also

play

size

The

had

has

but

the

will

for

12.29

fusion

nature

support

function

systems

operations.

for fusion’s

the reactors

The inherent

the possibility

and propulsion

systems makes

12.0 Conclusions

space practicality.

for both assembly

from first considerations

indicates those needs.

of being able to meet

The cost of and reuse essential

key role in the operational mission and staging for continued

12-9

tu_

for

that

13.0

listed

space

fusion

OF A

SPACE

FLIGHT

specific.

program

FUSION

Although

SYSTEM

continued

affordable

OPTIONS

application

The basis

technology.

PROGRAM

and power

it’s potential

as discussed

do not permit

in this section.

fusion energy,

as an enabling

from a minimal

to one designed

such a quantum

interest-indicating

the high operational

FOR DEVELOPMENT

funding in Section

program for the use of

although practical, Section

technology, transportation

and enhancing space

primarily is that chemical

focus upon to be intended to be both an

Program options for pursuit of space fusion are presented

Listed are four is presented tasks are provided

costs with using those sources presence

below range to make space fusion a reality. that

These options it is not is, has been stated provides capability

it must the enhancing and fission can perform the Manned Mars Missions

The program activities level a generic mission enabling leap for NASA’s considered designation

As shown by this study the requirements requirements diverge separate interests. funding

EXPEDITED DEVELOPMENT OF PROTOTYPE SPACE FUSION FLIGHT SYSTEM

levels for program options. 14.0. Recommendations

and power program such space

OPTION 1 : ANALYTICAL AND SYSTEMS STUDY TASKS

strategy high energy mission

SPACE FUSION EXPERIMENTS SUPPORT PROGRAM

DEDICATED NASA SPACE FUSION PROGRAM

SPACE FUSION RESEARCH

fusion a that and

PROGRAM OPTIONS

program is essential

for NASA to control

for space propulsion

from the terrestrial

The recommended

to serve NASA’s

The wisdom of

$50-100M/YEAR

recommendation

$10-15M/YEAR

$300-500M/YEAR

space It

by providing

for a space

is important

14 and 15.

OPTION 2:

OPTION 4:

in Sections

its energy

$1-3M/YEAR

sufficiently

OPTION 3:

objectives

for future

program.

destiny

fusion

a in

13-1

this

for

that

better

a dual

cooled,

to meet

nowhere

radiation

illustrated

sufficiently

application

for space.

applications

of electrical

is absolutely

of some of

It is expedient

The terrestrial

That capability

to focus more

space options

in the development

the key differences

into systems

that must be taken

the rate of progress

for NASA to implement

than by the DOE decision

in 1991 to cancel alternate

of light weight

can more readily accommodate

a space fusion its objectives,

for a propulsion function

of which fuel cycle, D-T.

system capability power

is deuterium than the mainline

NASA’s design maintenance

its missions its program plans,

terrestrial a requirement serve will

Space flight of high performance

and program goals, and to determine

13.0 Space Program options for Development of a Flight Fusion System

the D-T cycle. NASA has that

The space program is more The

options. capable to NASA. the physics program’s

research designs crucial and helium-3, terrestrial

program has advanced now, particularly upon the production

Below are examples consideration require propulsion. fuel of preference to achieve difficult

as new DOE endeavors power of net electrical program to its research fusion

fusion experiments. space can seize upon the technology can be expected experiments. accomplish needs,

program of $1-3 M annually would space fusion. an improved management indicates

on the part of NASA. Nine topical prioritized funding

reactor the fusion in one design will not

A minimally studies amount does not address

provide The life time and require

is not widely of in another.

funded on issues which to acquire

different configuration. community necessarily

is a minimal energy. in space fusion

in the fundamental outside of

This perspective a minimal

is that resolve problems

the tasks cannot be performed

and preferably generation

operational not available

of vacuum and zero gravity

tasks and task objectives

recognized details

are listed below in a

the key issues but

1: ANALYTICAL

AND SYSTEMS

for the indicated

to the terrestrial

of interest

reactor designs

The differences

level of $1-3M.

13.1 OPTION

using different

in applications

level of effort

the resolution

are different.

the conduct

Furthermore,

the physics

environment

approaches

application.

propulsion.

a reactor

STUDY

TASKS

annual

permit

All of

needs

fusion

order.

affect

what

13-2

and

1 :

TASKS

STUDY

OPTION

ANALYTICAL

PROPULSION

ALTERNATIVE

AND SYSTEMS

SPACE FUSION

AERONAUTICAL

REACTOR DESIGN

($1-3 M PER ANNUM)

of a Flight Fusion System

SPACE FUSION SYSTEM

INERTIAL CONFINEMENT

FLIGHT SYSTEM ANALYSIS

MAGNETIC CONFINEMENT
FIELD REVERSED CONFIGURATION

SPACE FUSION REACTOR DESIGNS

DUAL MODE POWER CONVERSION
STATIONARY PROPULSION POWER

13.0 Space Program options for Development

ALTERNATE SOURCES OF FUSION FUELS

concept. RACE upon the results of 13.1.4.

the means accomplish missions

and thrust variations key experiments

energy the type described

life. Also, one of the key items to address

which to achieve In the second

for a FRC reactor design for space

approach The first part:

the design FRC designed

propulsion set of detailed

the propellant mixing scheme

uniform mixing of the diluent

are the tandem mirror,

vehicle’s application.

efficiency. to confirm

Migma, be based

activity as is first wall

a 2-phase power.

phase of the activity,

to verify the model

conduct electrical

Perform a second

and subsequently

energy mission

CONFIGURATION

into the plasma

and the EFBT.

Using mission

to demonstrate

task is to test

(1) establishes

an appropriate

are conducted

the magnitude

for propulsion

One objective

for converting

ALTERNATIVE

is the means

The solution

requirements,

(2) performs

to thrust at

requirements

performance

for another

the optimal

is to model

1 analyses.

A corollary

REVERSED

establishes

a this

the space

Candidates

a part of

the phase

by testing

the fusion

It features

REACTOR

capability.

to 13.1.1

the MCF

approach

DESIGNS

balances

compact

and (3)

a design

exhaust.

to meet

classes,

focused

DESIGN

impulse

FUSION

toroids,

needed

plasma

SPACE

reactor

specific

should

similar

design

herein.

FIELD

13.1.1

13.1.2

those

other

Heat

1 3-3

high

task

from

and

are

for

of:

13.1.4

13.1.3

FLIGHT

POWER

SYSTEM

ANALYSIS

MAGNETIC

(3) moderate

in efficiency.

CONVERSION

CONFINEMENT

DUAL MODE

for MCF propulsion

(2) low 20-60 MW,

identifying performance,

for realizing improvements

(1) very low, <20 MW output,

feasibility and then, subsequently,

powers which may be achievable

Determine the range of Study systems.

13.0 Space Programoptions for Development of a Flight Fusion System

Conduct a detailed system study of a flight MCF fusion energy vehicle system

data from Section 2.0, conduct a for designing a dual propulsion and efficiencies, and concepts for

designed to produce propulsion and electrical power. specific the feasibility

Using the baseline mission requirements preliminary design analysis on techniques electrical power fusion reactor system, mass trades. Testing should be accomplished later to demonstrate

This study will evaluate the techniques for restart of fusion reactors in space. should requirements, which a fusion vehicle’s values shutdowns.

A system study on the use of fusion spacecraft either as energy engines propulsion Establishment

ion to power this of moons. times and payload masses

Perform the same study for a second option. This task is similar

the means by the reactor

for application and Mars-Martian

for the restart plus mission electrical

for an ablation this task.

power Investigations

techniques, and energy

(4) high, 1-20 GW jet power

include can be met,

system include Earth-Moon,

requirements. storage

Moon-Mars, flight

driven rocket or energy

ranges for the FRC.

is generic, whereas

200-300 MW, and

parts of this task.

13.1.1 is specific

AND ENERGY

levels, mission

to Task 13.1.1

The missions

PROPULSION

STATIONARY

of parametric

is performed

requirements

to the FRC.

duty cycles,

STORAGE

REACTOR

IN-SPACE

RESTART

levels for

comprise

including

electrical

powered

POWER

to drive

include

system

energy

restart

13.1.5

13.1.6

during

power

under

laser

13-4

but

for

ICF

this

The

fuels

focus

Pellet

fusion

$2.0M

13.1.7

space.

is the

should

energy

source

project

$0.30M

$1.20M

by the

SPACE

Fueling

FUSION

conduct

SYSTEM

concern.

research

a viable

INERTIAL

emphasis

to make

presumes

constitute

is higher.

is another

the value

comprises

for D-3He

evaluations

approaches

The VISTA

The major

to decrease

The following

of conceptual

CONFINEMENT

DOE program.

Research Project

activity for ICF:

study considered

that a satisfactory

a minimum effort

Manpower costs

The use of advanced

a gain of 1500 for DT;

Hardware and software costs

the driver size. also be evaluated.

target gain for space will be demonstrated

Advanced D-D-Fueled Designs

Excimer Laser & Optics Development

13.0 Space Program options for Development of a Flight Fusion System

Induction Power System Development

Plasma Conductivity Drag Determination

at simultaneously.

from a flying Earth

an alternative than

as opposed is a small

spacecraft fuels

Radiator Development

or to reach

in a safer, more

new non-terrestrial

chances merit.

AERONAUTICAL

ground means

for aeronautical

launch orbit

this capability.

The objective

at a mission

be conducted

its destination

PROPULSION

for achieving

as a means

and inbound

to determine

of deuterium

determination

ALTERNATE

of providing

requirements

the means

to consider

is to seek

exploration,

techniques,

to carrying

economical

The effort

SOURCES

propulsion.

preliminary

from the

the fuels,

propulsion

to refuel

and cost

to Earth

outbound

approach

analytical

helium-3,

reserves,

frequent

platform.

missions

planned,

recovery

whether

FUSION

includes

directed

sources

manner

$0.45M

$0.75M

$3.15M

FUELS

optimal

A very

figures

should

finding

Where

13.1.8

13.1.9

$1.0M

$0.3M

$0.5M

$1.1M

$4.9M

Totals

fusion

either

serve

could

effort

lunar

13-5

both

their

orbit

This

task

with

and

the

are

the

for

PROS

CONS

RESULTS

systems.

INTEREST

MINIMAL

Projections

ANALYTICAL

cargo of

for passengers

LEVEL TO INDICATE

ANALYSIS OF MERITS

OPTION 1 SUMMARY:

FUNDING INADEQUATE TO

ACCOMPLISH MEANINGFUL

on thrust and performance

FAILS TO PROVIDE NECESSARY

° PROVIDES FURTHER IN-DEPTH

Higher payload mass fractions

AND SYSTEMS STUDY TASKS

and/or fusion reactors

required for this mission class are to be included.

DATA TO VALIDATE STUDY ASSUMPTIONS

13.0 Space Program options for Development of a Flight Fusion System

chemical are the study goals. the category

in the DOE (a) To expedite having program. application to space but which have been assigned a low priority in the terrestrial program. These experiments could be expedited with Testing includes the FRC and other key compact additional is being space-related completed and the FRX-c Spectra Technology LSX experiment

test program, A low level experimental to produce obtaining energy DOE’s current programs that are of interest being terminated due to budget be funded at a reasonably some analytical work to be performed. 1

to space but which are in danger of could rapid rate to be of value to NASA and still permit

is the minimal designed assist NASA in The funding would be used to support

As this report is being dismantled is being terminated.

1Since this recommendation was initially prepared, DOE’s alternative

terminated. would have to be examined.

This is a leveraged, these objectives:

limitations. At this level, one experiment

funded test for space.

concept(s) those current

This option may now be more costly-it

results which may effectively

Some have been rapidly dismantled.

activity using DOE facilities

CONCLUSIONS MAY BE INVALID

at $10-15M annually,

It would supplement

experiments are being

the Los Alamos

to accomplish

EXPERIMENTS

experiments.

confinement

experiments

cooperative

testing of

PROGRAM

SUPPORT

OPTION

FUSION

funding.

already

SPACE

reactor

fusion

13-6

13.2

(c)

for

(d)

are

This

high

tests

have

focus

make

which

since,

fusion

space

power

D-3He

should

space,

energy

funded

reactor

physics

SPACE

sources

includes

OPTION

To test

reactors.

available

concepts

attractive

research.

ultimately

resources

programs.

as stated

otherwise.

successful

but which

conversion

techniques.

applications

this report,

experiments

confinement

The testing

experimental

To expedite

to ultimately

is considered

new plasma

by expanding

using fusion

for new high

are mandatory

are not being

of confinement

in the text of

and propulsion

will be performed.

test demonstrations

lead to understanding

to be the best use of

a space confinement

and objectives The conduct

(b) To provide on-going

in order space missions.

13.0 Space Program options for Development of a Flight Fusion System

COMPACT TORUS TESTING FOR SPACE FUSION EXPERIMENTS
FIELD REVERSED CONFINEMENT

TESTING FOR SPACE FUSION

the time of at

report this funding

($10-15 M PER ANNUM)

EXPERIMENT SUPPORT

preparation level.

necessary. terminated,

FRC for related

HIGH RISK-HIGH

Two probably

GAIN CONCEPTS

The reasons

is the space

plasma text.

beam injection

CONFINEMENT

EXPERIMENTS

at anticipated

Demonstration

EXPERIMENT

understand

ALTERNATE

REVERSED

confinement

experiments

this option

PROGRAM

net power

FRC and

are being

SUPPORT

eliminating

objectives.

(80 keV)

of D-3He

conditions

increased

TESTING

schedule.

approach

capability

important

durations

preferred

following

are the

expedite

FUSION

address

function

aspects

SPACE

support

burning

Testing

Neutral

scaling

current

in the

design

should

overall

FIELD

13.2.1

theory

is an

stated

active

proof

later,

even

task.

FOR

burn

13-7

long

with

The

and

is -

test

first

this

the

for

FOR

GAIN

HIGH

13.2.3

13.2.2

which

$500K

should

testing

SPACE

TORUS

FUSION

detailed

Specific

projects

follow-on

between

feasibility

TESTING

analytical

dividends.

COMPACT

for space.

RISK-HIGH

CONCEPTS

at a level

to $1,000K

experiments.

EXPERIMENT

can proceed

and possibly

useful yield

The critical

Some reactor

funding aspects

is best categorized

program. evaluate

to test and

reactor significant

later where warranted.

Test support would be at a minimal

be accomplished The concept

could be of new concepts.

This is a potentially amount

as potential be the goal of this general

130 Space Program options for Development of a Flight Fusion System

LEVERAGING WITH ON-GOING WORK

DOES NOT PROVIDE NASA IN-
CAN BE QUICKLY IMPLEMENTED
MAY ULTIMATELY COST MORE
EFFICIENT USE OF FUNDS BY
NEW CONCEPTS NOT TESTED

PRODUCE NEEDED TEST DATA

DEACTIVATED EXPERIMENTS
MAY NOT YIELD NECESSARY
NOT A QUICK APPROACH

LIMITED TO CURRENT, ON-

GOING EXPERIMENTS

DATA THE QUICKEST

CANNOT BE TESTED

LEVEL TO INDICATE

HOUSE CAPABILITY

DOE ALTERNATIVE

SUPPLEMENTAL

-FRC TESTING

FOR ACTIVE

EXPERIMENT

2 SUMMARY

PROGRAMS

MINIMAL

FUNDING

OPTION

CONS

PROS

13-8

IN-

13.3

NASA

PROS

CONS

funding

SPACE

FUSION

OPTION

program.

OPTIONS

PROGRAM

RESEARCH

DEDICATED

A moderate

2a SUMMARY

A NASA in-house

level of $50M-100M

HOUSE CAPABILITY.

FUND (LOW LEVEL)

NEW CONCEPTS TESTED

research this option.

DOES NOT PROVIDE NASA
GREATER TECHNICAL RISK

DOE FOR NEW CONFINEMENT

MAY ULTIMATELY COST MORE.
FRC TESTING NOT SUPPORTED
QUICK TO IMPLEMENT AND MAKES

USE OF EXISTING FUSION EXPERTISE

13.0 Space Program options for Development of a Flight Fusion System

ENERGY SYSTEM INCLUDING ALTERNATIVE CONFINEMENT

GOAL: DEMONSTRATE A FULL SCALE FLIGHT FUSION
PROVIDE AN IN-HOUSE DESIGN EXPERTISE AND TEST

OPTION: NATIONAL LABORATORY STAFFED WITH

research it does not pursue

This is a low level program to develop

DESIGNS AND TEST CAPABILITY

example, commitments.

fund a minimum level

flight program activity.

is one major objective

of critical milestones

a heavily committed

NASA PERSONNEL.

NASA FACILITIES

fusion capability

serious but

before making

issue, for

a commitment.

NASA SPACE

PER ANNUM)

reside within

demonstration

for a serious

investigations

an in-house

the Agency

to consider

for meeting

CAPABILITY

DEDICATED

that space

is intended

the issues

RESEARCH

organization

understand

the space

It requires,

technology

to commit

PROGRAM

to provide

operational

($50-100M

for space

equipment

to better

expertise

ultimately

approach

acquiring

expertise

OPTION

FUSION

success

as the

mission

support

energy

system

should

needs

heavy

critical

NASA

fusion

safety

goals.

Thus,

flight

13-9

This

The

and

will

for

3”

for

A).

life

but

test

fuel

any

and

that

and

The

high

than

solid

such

used

been

cells,

other

since

either

would

space

NASA

rocket

power

earlier

PROS

Center

funding

motors,

support

facilities

designs,

FUSION

OPTION

systems,

chemical

technical

including

capability

Research

additional

advanced

capability.

hardware,

(Appendix

propulsion

alternative

personnel.

Laboratory

technology

experience

the Lewis

a National

PROGRAM

of NASA’s

approaches

and design

To develop

with NASA

implemented

DEDICATED

they would

an in-house

technological

and so on.

3 SUMMARY:

it had already

of a full scale

is no different

NASA SPACE

flight a test

be accomplished

not be a unique

or, as an option,

are still applicable,

system is the goal

recommended NASA staff.

Demonstration concepts,

° ESTABLISH PROGRAM PRIORITIES TO

13.0 Space Program options for Development of a Flight Fusion System

IF SPACE FUSION PROVEN, MORE EXPENSIVE IN LONG

DOES NOT OVERLY COMMIT NASA TO °

FLEXIBILITY TO CONDUCT ALTERNATE

IF FUSION FLIGHT SYSTEMS CAN

FUNDING LEVEL SUPPORTS ONE

MAY BE LESS COST EFFECTIVE

BE PROVEN MORE NEAR TERM

HIGHER NEAR-TERM FUNDING

LEVEL TO PRODUCE NEEDED

EFFICIENT USE OF FUNDS

LESS QUICK TO IMPLEMENT

AN UNPROVEN CAPABILITY

DOES NOT EXPEDITE THE

IN A QUICK RESPONSE

DOES NOT EXPEDITE

SUIT NASA NEEDS

LEARNING CURVE

PROVIDES NASA

EXPERIMENTS

EXPERIMENT

CAPABILITY.

TEST DATA

CAPABILITY

SOLUTIONS

REQUIRED

MINIMAL

IN-HOUSE

MODE

CONS

TERM

13-10

4”

13.4

flight

funding

SPACE

system.

SPACE

develop

FLIGHT

NASA

FUSION

in order

OPTION

SYSTEM

in excess

($300-500M

a prototype

EXPEDITED

CAPABILITY

A high level

of $300-500M

PER ANNUM)

to expeditiously

DEVELOPMENT

A PROTOTYPE

OF PROTOTYPE

of a Flight Fusion System

per annum is necessary

13.0 Space Program options for Development

PROVIDE AN IN-HOUSE DESIGN EXPERTISE AND TEST
GOAL: DEMONSTRATE A FULL SCALE FLIGHT FUSION

ENERGY SYSTEM INCLUDING ALTERNATIVE CONFINEMENT DESIGNS AND TEST CAPABILITY

OPTION: NATIONAL LABORATORY STAFFED WITH

EXPEDITE THE SPACE FUSION CAPABILITY

a reasonable full

of providing would

NASA PERSONNEL.

have flight-like,

with the successful

the implementation.

chance system

is a high degree

for an alternate

be designed,

demonstrated

development

and would

confinement

3 approach

the Option

and flown.

FACILITIES

experiment.

of meeting

of built,

for space,

in a flight

application

has been

a concept

a source

approach

assumes

expedite

vehicle.

funding

provide

serious

parallel

system

energy

tested,

issues

higher

option

fusion

would

13-11

funds

scale

there

After

level

This

that

key

the

PROS

CONS

SPACE

FLIGHT

FUSION

OPTION

SYSTEM

REQUIRED

EXPEDITED

CAPABILITY

NOT WORK

4 SUMMARY

DEVELOPMENT

OF PROTOTYPE

SUIT NASA NEEDS

COMMITS NASA TO AN
PROVIDES NASA IN-HOUSE

UNPROVEN TECHNOLOGY-MAY

HIGHER NEAR-TERM FUNDING
EXPEDITES MISSION ENABLING
VERY COST EFFECTIVE IF FUSION
FLEXIBILITY TO CONDUCT ALTERNATE
ESTABLISH PROGRAM PRIORITIES TO

13.0 Space Program options for Development of a Flight Fusion System

FLIGHT SYSTEMS CAN BE PROVEN MORE NEAR TERM

CAPABILITY WITH TREMENDOUS PAY BACK OF INVESTMENT IF SUCCESSFUL

NEEDED FUSION AND FLIGHT SYSTEM

independent are summarized

ADEQUATE LEVEL TO PRODUCE

is estimated 13-1.

of $10 to 15M annually

IN A QUICK RESPONSE

at no less than

EXPERIMENTS

To commence

test program

a cooperative

in a manner

at a minimal

The options

$50M-100M.

experiments

SUMMARY

for space,

a practical

addressing

capability

that will

designed

in Table

in-house

program

needed.

conduct

benefit

MODE

fusion

DATA

13-12

have

level

13.5

and

level

conduct

options,

Focuses

develops

to develop

experiments

confinement

for a flight

development

an alternate

needed test

an extensive

Program Options

for demonstration

system analyses

Program Droducts

of data from the

Does not produce

on the generation

concept Pursues

Option 2- $10-15 M

Option 1- $1 to3 M

Option 3- $50-100 M

Option 4- $300 to 500 M

Studies only. data.

of net power. program for conduct

propulsion, development the

of electrical power, and key

most space relevant experiment. Is the minimal

TABLE13-1. Summaryof fusionannualfundingoptions.

13.0 SpaceProgramoptionsfor Developmentof a FlightFusionSystem

system on an

a prototype

expedited

system.

vehicle

basis.

13-13

flight

that

14.0

AND

relate

which

order.

PLAN

and of

SPACE

Options

strategy

as well.

FUSION

14.3.2.1,

(Anom90)

approach.

presented

will differ

PROGRAM

the earliest

STRATEGY

The overall

recommended

in a prioritized

are presented

possible time.

below for

the Aerospace

RECOMMENDED

to the demonstration

the fusion technology

strategies looking

shows the importance

program options were

initiating the program at

The program plan addresses

topics to validate system

been have and that an in-depth

The 13.0. results are presented

forwarded for analysis was For

and flight A flight strategy in Section

in tasks as appropriate. schedule, which is presented

strategy, Rocket Propulsion the “Advanced

critical Tasks are suggested fusion

from many it is more forward requirements recent

in Section and program plan based upon this study’s

Four strategy as the preferred space fusion application assumptions feasibility. included

This propulsion in that made of advanced as one example, prepared a “National 1990. document the suggested is assumed

With that strategy we will get nowhere for the reasons of of propulsion specific abreast made possible fusion energy

”…All of are funded small programs will determine Many of systems. the technologies propulsion ideas are not available A continuing many advancements energy conversion When a system concept on an acceptable

the text the real needs coupled with high to stay just best funds nor is it to develop

a lack of understanding power of high specific The $5 million, of

Strategic Propulsion as “Program NO. 7 - Fusion. That

15, the $5 million” as funding and priority

the technology productive level for space.

for near-term demonstrations. systems

to be based upon the text earlier where it is stated that

It reflects unfortunately the benefits in NASA,

Industries dated Concepts” 1991-2000.

(using has demonstrated

of etc.). capability

propulsion these advanced

the feasibility required

since the research

recommends effort

of are possible

in the basic understanding

and of fusion technology

experiment (Anom90,

the far-term programs

programs. these

Concepts These

using the theoretical

on more that

February chapter

stated throughout

impulse of

these propulsion

an expenditure

for this crucial

be conducted

or antimatter,

demonstration

is considered

in Advanced

in particular.

experiments

assessment

this report.

that allows

technology.

Association

of concept

is needed;

in general.

to conduct

the status

a practical

techniques

Propulsion

at a level

“Far-Term

research

Systems

level of

design.”

a proof

of for

needed

matters

known,

is well

theory,

should

status,

Under

fusion

Plan,”

p147)

small

14-1

are

14.1

their

there

Since

should

BASIS

energy

appears

attainable,

appropriate

high energy

requirements

requirements,

a high specific

space system

FOR THE STRATEGY

but key fusion experiments

and the energy means to meet

one that meets NASA’s mission

fundamental between NASA

of this report has been to consider

14.0RecommendedSpaceFusionStrategy

system analyses in agency the initiation

1 This program is needed to develop capability,

remain. goals and mission of a space fusion program by NASA is considered

Based upon considerable thought given to the projected mission needs and issues, this section presents a comprehensive program and logic for technical the efforts that are considered important to the future of the space program.

The objective the missions, those missions. This report requirements, shows fusion as the energy source having the greatest chance of fulfilling But it is the least developed of the possible sources. those requirements. Fusion energy and vehicle differences and DOE, necessary. propulsion program priorities.

space the DOE program is spread too thin to pursue its program can that

Fusion whether concepts application been sufficiently explore Further, space propulsion leverage fusion technology

What Section program strategy presented be done, who should therefore, activity.

If NASA is to make use of the time has arrived none of the reactor spacecraft expected

program. While for fits the requirements

nor for that matter were they and mission

7 and 8 to determine or has pursued propulsion power the DOE program has that NASA can now

be the approach? of The purpose using the information The strategy

in total as of what should It, from this

is the function Thus, taking advantage

1 As an illustration, note that current (FY91) budgetary restrictions are eliminating supportfor

in depth it is concluded related matters. and space

in Sections program may be pursuing

the alternate experiments considered to be key to NASA (Fpa90).

to date, has come a long way.

to reveal approaches a high energy

experiments the current which

highly of a space fusion

be accomplished. as derived

were examined terrestrial

from a space is that

a coherent in the study

broad-based to achieve

do it, and how it could

options were presented

are standpoint.

the work accomplished

needs as a result of

of NASA to develop

and power systems

for concepts

program approach

being developed

The conclusion

power and

this potentially

the preferred

is to forward

a description

the initiation

requirements

accumulated

this section

in the text.

technology,

the space

propulsion

capability.

rewarding

attractive

systems.

forwards

the fact

includes

to fulfill

funding

Lastly,

power

fusion

those

13.0.

1 4-2

Four

and

that

the

are

has,

least

been

study

which

-there

NASA

should

having

in this

reactor

around

explore.

THESIS

concepts

preferred

attractive

CAVEAT

high 13.

alternative

developed

are those

differences

developed.

The ones

The most

is developed:

from this study

14.0 Recommended

therefore, strategy

Space Fusion Strategy

A thesis recommended

implies to a hierarchical

case assumptions,

technological Thus,

the most of order

technical technically

energy exploration

In the development

to NASA space

ASSUMPTIONS

Space science

first consider

are prioritized

be of great

of a strategy,

fusion and

assumptions

objectives,

the most

provided:

structured

we must

impacting

difficulty.

benefi!

In the

issues.

below.

would

critical

These

study,

14-3

14.2

that

this

and

fuels

power

reactor

feasible

burning,

required

effective

systems,

products.

exhibiting

for solar

producing

10 kW/kg.

and flight

at a cost

is feasible.

operational

to produce

considering

Specific

requirements

Helium-3

4.2. Cooling

space are

Controlled,

4.1 A reactor

are acceptable.

in the amount

will be available

Stable plasma

restart specific

Space reactors

and shielding mass

interstellar missions,

capability powers

in space ranges.

use of preferably

stable plasma burning

in space fusion reactors

price for space missions.

Fusion Pro_lram Assumptions

8, and the like D-3He reaction

4 through reactions no neutron

14.0 Recommended Space Fusion Strategy

can be designed system science

assumptions low neutron producing

remote start and multiple can be designed within the necessary

propulsion minimum of ~1 kW/kg, are viable, preferably

output For are on the order of 30 GW for specific power systems

reliably years missions. system reactors vehicle

20 MW to 300 MW power missions. needed

in space on the order of up to 20-30 MW is feasible.

science missions, of space

6.1 High thrust up to 50,000 Newtons.

and 50 years minimum for stellar

impulses to 106 seconds.

for a Manned Mars Mission,

and manned jet power

6.3. Specific seconds

system can be designed

solar a necessity

exploration requirements

Fusion propulsion

can be achieved,

flight operational

and propulsion

system fusion

for: 4 months

from several

of 10 kW/kg.

A fusion

to electrical

Efficient

the reactor

is practical.

of charged

10 months

conversion

performed.

propulsion

Throttling

efficiently

for solar

thousand

reducing

to burn

particle

reactor

energy

Reuse

based

varied

power

fusion

costs.

direct

to 5

14-4

6.2

for

feasibility.

PROVIDED:

i!i_i

Demonstrate

3, POSSIBLE

and

14.3

flight

AND

I. The First Step-

FUSION ENERGY

fusion

MISSION ENABLING
SAFETY ENHANCING

FUSION

to make

PROGRAM

A FLIGHT

CAPABILITY

ULTIMATELY

TO DEVELOP

TO ADDRESS

an operational

i_iiiiiiiiiii!iiiii!ii!iiiii!ii!!!i!i

I NASASPACEFUS!0N_:X_M

KEY ASSUMPTIONS

IASSUMP.rIONSVAUD,

14.0 Recommended Space Fusion Strategy

to address the system is

ii!!i!_i_i_iiiiii_iiii_ii!_ii!i!_i!ii!i!i!iii!iiii _

The progression of the major program steps necessary assumptions presented in Fig. 14.1:

of fusion energy are to be realized, addresses

These range from research, of each of objectives

If the advantages be initiated identified

a program needs to were tasks

into 5 steps which The major

these steps are shown in Table 14-1.

Fig. 14.1. Progression of major program steps.

tasks have been divided

12 program element

the assumptions.

to development,

assumptions.

operations.

to validate

to flight

Twelve

14-5

that

the

and

flight

vehicle

Commit

Conduct

analyses

program:

feasibility:

IV. Flight

Determine

experiments.

demonstration

and exploration

fusion systems.

vehicle. Conduct

14.0 Recommended

to a NASA Space

V. Flight operational

build, and fly a flight

Space Fusion Strategy

and testing of concepts.

fusion to enhance

powered understanding

program: fusion powered

III. Develop prototype flight systems:

Perform fusion flight system analyses,

of the benefits Evaluate fusion’s

Include investigations objectives.

extended Commence preliminary

test verifications system configurations.

Design, technology maintenance

TABLE 14-1. Objectives: Major Space Fusion Program Steps:

mission flights of fusion systems development.

up vehicle design options studies.

I1. Flight vehicle systems definition: Show that

system requirements. are feasible. science power capability. related experiments,

and refine specific the fusion flight system aspects to NASA’s specific system

Demonstrate Fusion Program (SFP) and prove principles via the conduct of key fusion energy conversion

and exploration Pursue advanced

developmental, identified

five steps considered

may research,

provided be

program a

the assumptions:

content one

14-2 to validate

on the element

the either,

or operational

that comprise

accomplished

for each of

the major

vehicles.

in Table

program

science

Twelve

Details

phase.

below.

of of

major

goals

tasks

14-6

The

are

the

]]

III

14-2.

PLAN

Space

Fusion

TABLE

Strategy

of major

Summary

to validate

assumptions.

RESEARCH

program tasks

QUALIFICATION

OPERATIONS

FOR SPACE USE

PROGRAM STEPS

DEVELOPMENT/

14.0 Recommended

INITIATE PROGRAM

MAJOR PROGRAM TASKS

ASSURE FUEL AVAILABILITY
DEVELOP MISSION REQUIREMENTS
CONDUCT SPECIFIC POWER ANALYSIS
DEMONSTRATE FLIGHT SYSTEM FEASIBILITY
PREPARE BROAD BASED FUSION DEVELOPMENT
DEMONSTRATE NET POWER FROM FUSION ENERGY

1 1. PERFORM PRELIMINARY DETAILED FLIGHT VEHICLE

PERFORM CONFINEMENT OPTION PROGRAM

ASSURE LIFE AND RELIABILITY CAPABILITY.

EVALUATE SPACE START OPTIONS

CONDUCT PLASMA ANALYSIS

DESIGN OPTIONS

o_ Option

14-7

v”

V’

v’

_’

that

THE

STEP

fusion

TASK

14.3.1

FIRST

shown

overall

SHOW

reactor

SPACE

PROOF

14.3.1.1

FUSION

COMMIT

flow for

application

PROGRAM

PRINCIPLE

PROGRAM.

Demonstrate

DEFINITION:

for a space

in Fig. 14.2.

FEASIBILITY”

The suggested

DESCRIPTIONS

DEMONSTRATE

14.0 Recommended

Objective: feasible.

Space Fusion Strategy

Fig. 14.2. Step I- PROGRAM INITIATION STRATEGY.

This step contains

the initiation

I A_o,o_se I

of a space

four major

TASK4 I

program

I Top Level Space

TASK3

fusion

tasks:

op,to_

L___I

Pklsma analys_

T_K_

14-8

Build .ndtelt

APPROACH

SOLUTION

PROBLEM

TASK 1 Fusion

Program

Strategy

…

Fusion

Flow

Requirement

Corffir_fT_ff

FRC

No High

I I

workshop

Helium-3

Program

program

M_sion

Energy

Fusion

Sp_0e

ntiate

…

..,,.,.°

I”

…

..,…

°,o..,

]

THE

KEY

circle

TASK

Space

“NASA

Fusion

SPACE

ISSUES

program

FUSION

program.

INITIATE

ENERGY

for Step

Proposed

14.3.1.1.1.

develop

PROGRAM”

AN ACTIVE

CONVERSION

TECHNOLOGY

program plan.

TO ADDRESS

14.0 Recommended

Program Tasks

Space Fusion Strategy

addresses the thesis.

an initial comprehensive

initiate a fuel availability

initiate a FRC experiment

initiate a space fusion program

It is designed to break the and mission space mission then NASA would use it. NASA has including the for

A Space conducted and which made important A). resources. which personnel

conflict” between mission requirements A need exists to actively pursue a high energy If the capability for the conduct

NASA had previously focused program which was space (Appendix to fusion technology is to make the maximum use of available

Space fusion energy energy density mission. NASA’s and ultimately capability accomplishing organization

accordingly technical minimize made from an independent particularly advanced

This recommendation “vicious capability. capability. the charter the development conduct

limited and highly mission constrained; impulse from

in those is necessary to be cannot basis, a factor become more

existed, of space and aeronautical means conversion

new high energy missions. on the operates

the lack of a high specific space

disciplines program risks. Otherwise,

would stagnate bold which

Higher to NASA’s

and hence

and more powerful high levels

and prevent NASA, of

it a research technology,

of its broad category

Program would successful

sources space missions

of space and aeronautical missions.

judgment and technology

should possess which

Consequently, optimal

the hands-on it utilizes.

existing there would

fusion contributions

energy of energy,

is to use where

research, necessary

power, programs

and one fusion

and knowledgeable

future - becomes

critical whenever

is within NASA’s

and the energy

levels increase.

as one option,

The pragmatic

The capability

not be new.

at a national

and facilities

high specific

management

the prudent

the energy

competence

are critical

laboratory

and best

approach

decisions

leverage,

technical

research

solution,

interest.

NASA’s

Without

domain

leading

energy

Fusion

a very

offers

edge

14-9

for

but

the

civil

too,

that

and

one

The

with

labs

may

time

staff

have

is to

That,

costs

avoid

would

LLNL,

fusion

space

NASA

option

facility

it with

option.

Facility

require

greater

parallel

design,

already

servant

mission

another

aspects

industry

Institute

Another

contract

similarly

program

it would

although

operated

program.

servants.

planetary

a NASA

capability

a longer

operated.

University

objectives

conflicting

laboratory

programs,

spacecraft

suggested

and staff

the work

to initiate

component

completely.

relationship

a separate

to perform

this would

to conduct

but which

is to build

complement

a dedicated

here would

A university

in existence

up a is to

of California.

for example,

the terrestrial

that between

use NASA

of Technology

under are

the technology.

to the program

has advantages,

to be examined.

NASA’s another

building Another

on a confinement

The two separate

14.0 Recommended

Space Fusion Strategy

the FRC work while

a national civil

operations, contract

they could The

is operated other

and DOE’s, in some

and the Jet Propulsion-California

and other to DOE via

functions. the University

the advantage of

of being and of being maintained

it can be reduced favorable the most

to ignition using by the beam flux.

to approximately characteristics

is believed beam injection

neutral beam injection to increase

current to 2 per cent.

series demonstrating

as a key part of the technical

experiments capable

that goal and for NASA’s

To address energy

this point can only be

1 and 2, demonstration

and ignition verification

to be the FRC

risk FRC reactor

of is to test

achieving FRC.

using high energy

step, a space

for an engineering

for burning D-3He

quickly The

of understanding

plasma neutral

heated stable

In the ultimate

to the required

one consisting

This program’s

to be capable

and preferably

at D-3He.

high fusion

is to develop

This empirical

task objective

EXPERIMENTS

developmental

of a minimal

is appropriate

be conducted

is considered

by a science

as discussed

40 keV ion

be achieved

temperatures

of energetic

is to initiate

are options.

The reactor

and plasma

to increase

assumptions

of neutrons

is essential.

a minimum

experiments

by funding

The dipole

temperature

PROGRAM”

projections,

the design

the energy

a program

is another.

of burning

a valuable

to provide

considered

technology

application

by-passing

the depth

the option

REACTOR

producing

for space

approach,

14.3.1.1.2.

regardless

expedited

aoDroach

therefore,

it cannot

particles.

magnetic

program,

progress

numbers

reaction,

strategy.

INITIATE

compact

oreferred

absence

strength

charged

for

stability

a goal.

FUSION

oro0ram

neutron

burning

desired

should,

Plasma

SPACE

toroids

provide

having

D-3He.

values

reactor

below.

aimed

solely

sense

taken.

TASK

fusion

14-10

TEST

Other

“FRC

large

level

AND

goal

FRC

with

field

The

can

but

the

still

will

14.0RecommendedSpaceFusionStrategy

The objective, then, is to demonstrate for flight conditions the burning of D-3He as quickly as possible without gaining a scientific characterization of the plasma. Thus, the first goal is to advance the FRC reactor to a D-3He burn configuration.

While the approach is to advance the FRC to burn parameters without understanding of the plasma science, that understanding is considered important to the program in the long term. Hence, there is a necessity to conduct analyses of the reactor’s plasma to characterize the confinement sensitivities to variations in operational control parameters (Task 10).

program and has, in fact, been a path successfully taken to implement prior inventions. This must be accepted as an expedited but high risk approach. The magnitude of the gain to space programs justifies the risk level and warrants the recommendation. In considering the “at risk” funding level later in this section it should be emphasized that those cost estimates are no more than educated estimated judgments to demonstrate plasma stability in an FRC. To better define the risk, more definitive cost estimating must be performed concurrent with the results from more refined analysis and experiments, an iteration process.

Using a high risk FRC approach we would proceed without delaying for the workshop discussed below. As a different confinement approach using an optional design (Task 9), the SFP could conduct experiments 2 on non-Maxwellian systems for example. The goal is to avoid a critical single failure point with regard to conducting research on one fusion It is also to advance technology by examining less confinement scheme. defined concepts that may hold high promise for space applications. The funding availability will obviously determine whether or not options are possible. It would be preferred to conduct a parallel multiple experiment program on the order of 4-7, funded at a cost of $10M per program. This avoids falling into the trap of relying on a single approach. Suggested

Table 7-3 characterizes the basic reactor parameters for a 500 MW reactor. If D-3He burning is not successful, the D-T operational regimes can be tested. D-T, although not the preferred fuel, could still serve a function in the accomplishment of space science and very useful exploration although considerable advantages are lost. If that situation occurs, efforts should continue to further pursue either the FRC D-3He fuel cycle or alternative advanced plasma confinement concepts in this or other reactors.

2 Thereis a distinctionmadebetween”reactor”and “experiment.""Reactor”in this report refers to energy conversionequipmentproducingnet power. “Experiment”refers to investigationsof machinesto verify concepts,analyses,and theory. Hence,“experiments” are not necessarilyof an operationalregimewherenetpoweris produced.

14-11

for

the

over

TASK

PLAN

options

product

FUSION

systems

PLASMA

ENERGY

14.3.1.1.3.

generation

PROGRAM

anticipated

FOR THE

ANALYSES

14.3.1 .1.4.

confinement

OF SPACE

PREPARE

of the reactor,

CONDUCT

DEVELOPMENT

results attained.

will be a major

A PRELIMINARY

approaches workshop.

14.0 Recommended Space Fusion Strategy

is essential power regime.

thrust and electrical power conversion systems. A level of effort This for the successful use of the reactor, engine, and flight

The plasma analysis task supports understandings conversions, must be expended to understand the experimental knowledge electrical operational

having in the application of fusion energy to space, organized for the and issues to is to of an Initial Space thinking the initial FRC

This task initiates a workshop of fusion scientists and engineers an interest purpose bringing forth the best set of ideas, address in a Space Fusion Energy Program. provide at the workshop conclusion, Fusion Program Plan which has been defined using the best available. testing defined

A reliable source and storage means of 3He, assumption space means to provide solid state,

The long lead time anticipated study appropriate. of

A comprehensive 5. An alternative system users planning. established establishing

in Step II, Task the flight the initial be thus to devoted

The production Fuel supply options are to be evaluated.

application. and store large quantities could be considered.

of mission an advanced mission workshop

and after the mission in Task 5 would be appropriate.

space mission workshop is to hold a joint working

that an early would be are to be a part

An initial by conducting science

is suggested group at

to the the in the of a 3He

production qualification, planning

the development, options,

is a long lead time item to support

between of would

This task must also consider

and flight program activities.

have been more thoroughly

after requirements

and exploration missions.

A follow-up workshop

The establishment

efforts, for

and the fusion

PARTICULARLY

The objective,

and economics

the completion

AVAILABILITY

3He indicates

the elements

requirements,

a dependable

the technical

of deuterium.

the sources

technologists

requirements

to establish

for example

to prepare

operations.

to provide

technology

14.3.1.1.5.

HELIUM-3

production

the study.

performed

the Step

the time

ASSURE

feasibility

in Step

Storage

is vital

supply

FUEL,

facility

TASK

fusion

Study

14-12

!I3He

then,

Also,

and

fuel

are

the

set

for

flights

(based

amount

envisioned

and initial

quantity

important

is (in kilograms)

for provided

of 3He should

The minimal Table 2-7a)

have been completed

testing in Table 14-3:

14.0RecommendedSpaceFusionStrategy

TABLE 14-3. Preliminary estimate of 3He requirements (kg).

Testing (based on 2x Manned Mars mission firing time)

processing technology for deuterium and 3He is to be studied, and preferably a pilot model demonstrated. This study identified terrestrial sources for 3He. For the space application it and extraterrestrial eventually may become sufficiently to manufacture the element. This may be necessary in the event that a limited terrestrial source can be made available prior to a lunar supply. A clear definition of the fuel demand, based upon mission objectives planning, and the means of its supply should be addressed. The plans for acquiring the for anticipated implementation in Step I[.

This task could be defined as one which serves as a precursor program preferred suggested level of $5M per approach, over 2 years. $50M, for 3 yearsEwhich be delayed

The above assume a 1 kW/kg system operating of kilogram of 3He will produce sufficient 3He supply required to conduct a space program. use of hydrogen

in depth at a at a cost of the program would in as discussed

to any design studies of the the workshop

One There is a is by the has been

that would If the top 10 suggestions

the program would The disadvantage

at 70% efficiency. power.

Jupiter Manned Mars

It would consist of detailed

demonstrated. examination

the program has progressed.

3He may also be conserved

Asteroid hopping (6 visited)

approaches above.

tests once the D-3He

but a larger supply

CONFINEMENT

a test program,

be a product

and a subject

test objectives

to commence

19 MW-years

were studied

is a function

for selected

be initiated

14.3.1.1.6.

OPTIONS

Options:

be very

reaction

activity.

spread

is that

TASK

fusion

would

14-13

costly

Pluto

Total

after

That

for

.1.7.

THE

AND

10.0.

study

could

Show

better

STEP

TASK

14.3.1

is that

vehicle

Section

reactor

is that

INITIAL

FLIGHT

analysis

problem

vehicle.

DESIGN

OPTION

14.3.1.2.

SYSTEM

powered

SECOND

VEHICLE

in reality.

Objective:

to permit

developed

PERFORM

ANALYSIS

The other

of a flight

may apply

The the

this nature

FEASIBILITY

the converse

A preprogram

be conducted

understanding

in the results.

is inadequately

DEMONSTRATE

be invalid when

concern level

quantify resulting

high level of confidence

of a fusion study

the study may show concepts

14.0 Recommended Space Fusion Strategy

the capability from a preliminary

capability high energy mission

! and the mission vehicle preliminary

system prototypes. and testing.

configuration(s) data, test

fusion’s be appropriate

understanding point

results. requirements,

experiments to succeed.

up through related

The FRC is considered

conduct considered

of accurate,

on the Without

system feasibility

system analyses

the determination

be accomplished.

as an illustrative

will be possible.

reactor reactor

the top priority

space mission

power likely

and therefore

has assigned

the feasibility

and is used

in Fig. 14.3.

and conduct

demonstrated

requirements,

requirements.

demonstrates

As the first

performance

verifications,

], a better

experiments

net most

The Step

From the

of viability

technology

of vehicle

contender

determine

feasibility,

I! overall

to define

of space

is shown

flow for

extended

example.

analyses

in Step

the test

to meet

in Step

question

credible,

in Step

it would

program

a prime

systems

produce

be the

strategy

Perform

designs

system

study’s

always

to the

results

power

fusion

space

fusion

14-14

Thus,

Once

study

there

been

step,

flight

and

has

can

test

this

net

the

will

STEP II Program Flow

14.0 Recommended Space Fusion Strategy

In Step I of 3He will have been studied.

for deuterium and of

the program the fuel production

develop mission requirements

Fig. 14.3. Step I! program flow.

perform plasma analysis
show system feasibility

options the validity

(Task 6, Step I option)

(Task 9, Step I option)

(Task 10, continuation

space start capability

conduct alternate

(Task 4 continuation

This step contains

Proaram Tasks

PARTICULARLY

demonstrate

specific power

the production

AVAILABILITY

(CONTINUED).

from Step [).

from Step I)

a fuel supply

establish
establish

experiments

14.3.1.2.1.

ProDosed

HELIUM-3

Preferably

for Steo

(Task 5)

(Task 7)

(Task 8)

ASSURE

7 major

Fusion

Soace

FUEL,

TASK

tasks:

14-15

for

the

i.e.,

and

that

.2.2.

FOR

AND

likely

been

plans

point

HIGH

future

TASK

14.3.1

SPACE

concept

in Step

of Step

A SET

helium-3

thinking

acquiring

are II.

ENERGY

MISSION

precisely

SCIENCE

to task

therefore,

interested

anticipated

MISSIONS

to assure

the need

exploration

This task,

to address

in time for

the second

need, most

by the start

A workshop

to stimulate

requirements

high energy

requirements.

transportation

DEVELOP

are forwarded

EXPLORATION

the anticipated

REQUIREMENTS

is demonstrated,

define mission

the user needs.

the future space

science mission

14.0 Recommended

capability HI.

have develops

A task is necessary

raised in the caveat,

Space Fusion Strategy

expected The Step

space that proper

of quantity implementation

is to insure to the system

developed the fuel production

task and ultimately will meet

than the 80 MW size. With technology

with the space effectively

and exploration associated

fully Scientists activities

implementation an ascending

Workshop understanding

may demonstration.

requirements. power

delineating requirements

and the lack of a mission

science traditionally

to be more likely to meet

the 250 MW technology

A better durations,

is thereby situation

This task circuitous

the program to most

could be time phased

to match anticipated

in the study thesis.

originated missions

are not broaden

between missions

mission feasibility

order of difficulty

the energy

recommendations.

system for

further the of

as one critical

to the system

are necessary

be assembled

use the new

the workshop

developmental

of workshop

as presented

is to include

the 1 kW/kg

is considered

requirements.

as an input

who could

This subject

complements

is discussed

requirements

to terminate

of workshop

performance

is prepared

of a high

in Section

Technology

that more

the space

considered

From the

objectives.

objectives

capability.

objectives

this time,

document

workshop

scientists

capability

examples

progress,

progress.

products.

Research

discussed

research

a space

program

masses,

reactors

purpose

initiated

element

payload

become

feasible.

to date

report’s

science

smaller

to the

system

results

energy

should

Fusion

levels,

activity

reflect

fusion

Space

further

These

below.

which

depth

in At

14-16

been

have

level

high

This

lack

may

The

due

The

etc.

not

are

the

15,

level

TASK

power

POWER

is crucial

SPECIFIC

14.3.1.2.3.

for space,

of meeting

DEFINE

PRECISELY

the conduct

required for

the necessary

14.0 Recommended

is encouraging.

level of specific

Space Fusion Strategy

AND ESTABLISH

CHARACTERISTICS

for mass reductions.

and research endeavors

discussed in this report.

of attaining 1 kW/kg to 10 kW/kg,

the third assumption, and specifically

Specific power, the feasibility

and the very preliminary experimental

rather than to initiate testing as suggested.

the assumption of to the attainment

system design study could be accomplished

analysis work accomplished investigations

A preliminary step in the strategy studies

The very preliminary Because of the specific power design work and to establish

That design as to for This entails the design of of space

of the mission objectives systems lack of detailed should be undertaken to better quantify this parameter

approaches activity should be performed to provide a preliminary assessment the feasibility attaining advanced science mission objectives. reactors of the power output missions.

that another study, accuracy of system parameters emphasis has been placed upon spending dependable

regardless of the funding level, will lack the necessary the to produce credible results. funds on testing so that more

performance, and the operational system for while meeting thrust

integration the science of the successful, unique for space systems

ability life projections, reliability, to the flight environment produce

to address This is a very extensive the fusion space flight vehicle, assumptions

a program vehicle powered with fusion here. the reactor’s

impulse high 6) are part of the task. Task 7 uses

space which systems spacecraft. energy The goal

safety, vehicle system controls aspects

of the critical 4, 5, 6, and 8. This is also a

such as supplying reactors of power

as the first From the it was concluded

the specific from an FRC or other

including AI, power in the space

CONDUCT RELATED SPACE DIRECT SHIELDING

vehicle system analyses can be subsequently

as well as the specific

Therefore, capability performance

to perform in a space flight system.

vehicle researches critical

the integration safe operation

are investigated of

in this task will be the ultimate

DEMONSTRATE: IMPULSE,

of all space of a fusion

the specific to deliver

power the variable

requirements fusion

THRUST, CONVERSION,

PROPULSION, DESIGN,

ENGINE, ANALYSES,

for The very

that are associated

DEMONSTRATE

in other words,

system aspects

the propulsion,

This includes

PERFORMANCE

demonstration

FEASIBILITY

(assumption

applications

performed.

ELECTRICAL

controllable

capabilities

conversion

14.3.1.2.4.

test data,

restarting

SYSTEM

COOLING,

electrical

research

potential

Instead,

SPECIFIC

and to

VEHICLE

reactor.

activity,

SYSTEM

remote

POWER

project

FLIGHT

START,

LEVEL,

TESTS.

issues

TASK

14-17

thrust

AND

and

conversion

to achieve, particularly at

14.0 RecommendedSpaceFusionStrategy

5,000 seconds using uniform, efficient mixing of

the space start/remote restart results from Task 8 as an input. There is an option of using the Step ! reactor in Step [I or to design a new reactor, depending upon the results achieved in Step [.

Reactor power output levels and efficiency are to be demonstrated. Of interest here, too, is the ability to throttle the specific impulse down to approximately the diluents while maintaining efficient fusion burning (assumptions 5 and 6). Optimal diluents from the standpoint of system considerations are a part of this effort. The diluent of preference from the reactor’s operational characteristics may vary from the system’s optimal mass, and that question is an important one to investigate in this project. The means for control of the reactor and fusion system is also a part of this major task. The efficient of plasma energy directly to electricity (assumption 8) will have profound system implications but may be a difficult engineering feat the high level of efficiency desired, at the low level of rejected heat desired, and for meeting the long life reliability requirements.

Other key points raised in this study are also to be addressed in Step II. These include determination of the requirements and the means to control the propulsion system. The analysis conducted in the study shows great safety advantages, but assumptions are necessary due to the early state of the technology at this time. At the time of the initiation of Step I! space fusion reactor technology should be better understood and fusion spacecraft safety should be analyzed. The economics reported herein are predicated upon the feasibility of fusion engine system space the reactor’s storage and reuse capabilities. operational characteristics accomplished at this point in the program should likewise assist in the development of that important assumption.

As part of the task to better evaluate and ensure that the required specific those power start analyses capability those for space requirements, Following programs, the analysis, implementation those

best meet subject no work has been performed.

assumption is one where optional techniques are to be evaluated

thereby testing The the start-up mass. start-up

this project provides to define the requirements establish

space understanding developmental should

should indicate The experiments approaches

for the conduct of reactor

is achievable, necessary to and

design by experiments

better of the areas for

A better definition of

approaches and testing.

that will is a critical

empirically, mass.

for From in

DEMONSTRATE

concepts This

defined vehicle

test evaluations,

START/REMOTE

be instrumental

the technology

in establishing

system starts

14.3.1.2.5

CAPABILITY

for a space

A SPACE

RESTART

enhancing

reducing

TASK

fusion

14-18

which

flight

and

4.1.

our

but

will

for

That

AND

effort

Some

TASK

power

should

specific

thinking

Part of

14.3.1.2.6

to inertial

this task’s

UPGRADE

capabilities.

approaches

confinement

approaches.

Suggestions

for alternate

confinement.

The content

confinement

ALTERNATE

the workshop

CONDUCT

it are products

EXPERIMENTS

14.0 Recommended

PERFORMANCE

to be a product

Space Fusion Strategy

reactor is a very

too, in Section

emphasizes should

the fusion workshop. here.

into the experimental of

the necessary to be included in this task.

This report consideration considered, provided

The means to store the start-up level

magnetic also be given of 13 are applicable

for The idea is to provide an initiative to

provide achievable energy while still maintaining significant matter

This task uses the results from the space fusion technology workshop to test incorporate alternate program. and planning and the progress of the FRC testing. stimulate

An experiment implement already approach point. early in the program due to the lead times and due to the long operational mission firing durations.

like spin polarization potential space power.

there will be opportunities includes task the redesign. of

program single failure are suggested research

there. to avoid a critical of alternate,

test program and test data to be

It is expected are obtained, improved. upgrades,

been is desirable The initiation

and very high risk, high gain approaches

Following maintenance. specific

analysis power conversion

research several megawatt

this and verifications

task supports systems.

large gigawatt size.

The plasma electrical

could also be considered

that as the FRC or other

having key start

and other space

there one which

technology towards

this step, task,

involved with fusion

such as reduced

of of effort

task to has

flight applications,

there is an effort

An alternate

of enhancements

the completion

an appropriate

non-Maxwellian

(CONTINUED).

improvements,

for significant

improvements

and systems

investigations

under Task

an optional

conversions,

performance

confinement

approaches

is included.

is oriented

parameters

ANALYSIS

REACTOR

is a need

in specific

the initial

the small

suggested

propulsion

14.3.1.2.7

PHYSICS

PLASMA

approach

improved

identified

research

systems

A level

SPACE

reactor,

include

Hence,

reactor

Clearly

design

option

power

TASK

14-19

thrust

Also,

and

for

the

and

THE

AND

STEP

phase

THIRD

FLIGHT

14.3.1.3

DESIGN

SYSTEM

SYSTEMS

DEVELOP

of Step II

is complete.

development

from fusion

requirements

HARDWARE

the program

PROTOTYPE

the research

understanding

of net power

PROPULSION

SPACECRAFT

the conclusion

DEVELOPMENT

14.0 Recommended

of feasibility

Space Fusion Strategy

With the demonstration

and demonstrated

Objectives: the vehicle

requirements development must

A supply should be in production,

the program up to flight

I) and a flight system

is prototype option

study will be accomplished

preprototype the

Step new ones:

[I), the critical

show system feasibillty

phase of the program.

toward The long

propulsion lead

can be anticipated

A larger quantity

life and reliability

Using extends

3 (CONTINUED).

system item.

be demonstrated

III leading

this vehicle

Phase A flight

system study

AVAILABILITY

determinations.

demonstrations

a fuel supply

in the fourth

developmental

can advance

the conduct

five program

(Step of

A aerospace

flight weight

and initiates

the program

maintain

4 continued)

7 continued)

of helium-3

(Step for

9 continued)

maintenance

configuration

of meeting

performance

qualification,

from Step

It continues

the design

for optimal

to provide

technology

ProPOsed

for Step

developed

14.3.1.3.1

hardware.

A typical

is clearly

hardware

Program

[[, Step

systems.

contains

3 tasks

conduct

through

S Dace

Fusion

options

in this

phase,

design

Phase

Tasks

critical

TASK

tasks.

FUEL

14-20

(Task

those

since

step.

flight

step

this

The

12).

and

first

the

for

III

I[!

for

7.7.

7.6.

TASK

POWER

FUSION

SYSTEM

in space

14.3.1.3.2

necessary

14.3.1.3.2.2

14.3.1.3.2.1

PROTOTYPE

ELECTRICAL

as possible,

an advanced

PROPULSION

flight hardware

the successful,

7 (CONTINUED).

test duty cycles

and the operational

the efficient including:

and test of I in Steps

power system to investigate

It includes design, manufacturing,

14.0 Recommended Space Fusion Strategy

should reflect the anticipated flight use.

energy level, controls, environmental

to the design, manufacture based upon the accomplishments

The SFP program advances prototype and II.

This task produces parameters conversion system. critical equipment power by fusion efficiency, power performance, operational modes, demonstrated.

The system test configuration should match the projected flight designs and as closely environments

critical safe use of the space electrical power and test of the of electrical systems, effects on operational Dual should be

improving endeavors initiation of the capability are not provided in this document. further to NASA’s capability and therefore its although A task is provided to operational indicate the need in Step II and beyond. As one project within the task it could, in the current technology are also included as part of this task.

This task, a typical Phase A flight system study to establish space flight configuration The Phase A study will provide the system level requirements which the fusion system will be required to meet, vehicle to be and ultimately design/performance built

Since this study is focused on flight programs and the implementation of fusion energy to enable science and exploration flight programs and for

for example, continue the confinement option task. Advancements

discussion concerning maintenance

beyond the There is no

of the existing technology

success with using fusion

at the end of of Step III.

such an activity is crucial

production heat

system level analyses,

and power combined,

a better definition

ground and flight

the configuration(s)

9 (CONTINUED).

is accomplished

i.e., propulsion

in Phases C-D.

MAINTENANCE

TECHNOLOGY

evaluations.

A FLIGHT

and safety

A FLIGHT

14.3.1.3.4

14.3.1.3.3

SYSTEM.

VEHICLE

research

rejection

options,

DESIGN

energy.

options,

PHASE

STUDY

safety,

TASK

1 4-21

for

task.

LIFE

levels

TASK

key for

it during

experience

of concept

The viability

14.3.1 .3.5

the conduct

lower energy

to stress test

the attainment

ESTABLISH

of high reliability.

LONG RELIABLE

in part accomplished

and to demonstrate

The study can be at

The life and reliability

the solar lower

along with other options

redundancy. of steps

requiring in off-nominal

that approach least

14.0 Recommended Space Fusion Strategy

has been the reactor design

high reliability. One verification technique

Once and verifying to achieve

the proof the overstress an interstellar

is to test a fusion reactor which has been designed to

That would at least appear of

system missions energy missions of

those level which is more representative

effects, capability with a high confidence real

and to but at the high power the design needs to in the plasma for obtained could

An initial phase of Task 12 will provide a plan for the optimal means achieve for consideration

perform at operate higher power output demanding missions. concept. be studied. analysis predicting be upgraded factor of meeting mission success without As an option, operational become hardware subsequent activity which acts in a building block fashion to produce

progress parameters reliability missions alternative conduct approach ignition scaling laws. depth operational means to achieve

The demanding be best accomplished physics, variations effects Involved recognizing thrust missions,

effects parameters, failure modes. early, low The program should

overstress by this study has been to advance understanding

time life testing. may conditions is in all an

of plasma Task 12 would provide an in- reactor

from the simpler, to establish life test verification like the Oort Cloud

to plasma for all critical and and testing. firing durations

less demanding base. program would

by a full understanding instability,

test time long for The to

and Alpha Centauri of plasma

demonstrated That understanding

high reliability mission goal, assumption

of: performance operational

here are analysis the length of

a comprehensive is successful,

engine and power system reliability.

attaining If that approach

system and recommended

is to use the understandings

involved with high energy,

severe into a real

The the reactor

Another is continued

This program commences

the program to indicate

will serve as one key

the need to continue

and/or principal

system operational

of the technology.

and the newness

be prohibitively

and deviations

its sensitivities

characteristics.

to the more

understanding

of process

Proceeding

the space

component

variables,

missions.

reliability

reactor’s

design’s

number

a data

physics

testing.

without

reactor

7, can

option

14-22

data.

FRC

task

the

ERA

difficult

and to

FLIGHT

14.3.1.4

vehicles,

STEP -

VEHICLE

14.3.1.4.1

the more

is needed

to support

PROGRAM

to maintain

applications.

one to address

THE FOIJRTH

and to advance

science missions

The advancements

and to understand

Design, manufacture,

life limiting processes.

fusion a technical

to continue support

Objective: flight vehicle.

the manufacture space

14.0 RecommendedSpaceFusionStrategy

capability are necessary support

Step Iv contains flight technology.

two major programs, the other The technology

testing, From the are of The 250-300 MW the Manned Mars Mission while the The 250 MW reactor, the manned qualifies qualification test demonstration is discussed That approach

A flight vehicle fusion preliminary are the typical through integration, of results interest, size is considered 50-80 MW size captures applied flight. program, further

analyses, options flight vehicle system design, manufacture, assembly,

built and qualified. qualification flight if the qualification

from the space and the Included here for Phases B

science mission, the flight the system.

to an unmanned is considered “man-rates”

Phase B. This is the standard Phase B design selection

The list below summarizes of Step IV.

of Task II, here a flight One option

system is of the be initially purposes

a 250 MW and a 80 MW (jet power output).

vehicle design process used on NASA’s

by Step II[. program activities

flight checkout, study, this

is to conduct in LEO.

is the goal of Step IV using

and flight two reactor

It should for checkout

and qualify a high quality

qualification test.

tested in the operational

test program in space

the science missions.

testing is not partially

flight one that

studies, design

fusion propulsion

A continuation

flight vehicle

space fusion

accomplished

the activities

the mission

first That

experiments,

and testing

to complete

environment

this phase

appropriate

in Step V.

information

aerospace

and flight

programs.

program’s

a portion

in space.

produced

analysis

needed

vehicle

1 4-23

sizes

for

will

the

are

into

and

built

time

very

Two

flight

used

been

flight.

made

which

space

where

orbital

tested

testing

initially

vehicle

is built

mission

science

vehicle,

through

indicate

validate

aspects

isolation

involved

alternate

systems,

scenario:

In space

obtained,

hardware

important

approach

strawman

to fusion

controlled

Economic

adaptable

emissions

approach.

simulators

in space.

propulsion

suggested

for space

expensive.

Phase

a manned

the above

the hazard

C. flight

approaches.

the present

is presented

the neutron

the size of

representative

make There

is assembled,

as a program

ready Unlike

the equipment

in the vehicle.

and a smaller

by a disposal

trades, will

characterizations

vehicle. have

launch, small

to an unmanned

Flight vehicles

activate materials

flight definitive

14.0 Recommended

flight systems.

checkout That

discarded program.

this time is believed

Space Fusion Strategy

The flight orbit,

after more the

and is attributed

and qualified to support

Phase D. placed

chemical are particularly

good, is also the safety

conclusion the into a safe orbit around

requirements is continued.

7 & 9. TECHNOLOGY

The program content

at this point contains

a three tier activity:

the the sun.

the test program

understandings

MAINTENANCE

are continued.

TECHNOLOGY

of advanced

technological

improvements

development

RELIABILITY

incorporation

The vehicle

to pursue

to produce

technology

14.3.1.4.2.2

14.3.1.4.2.1

DURATION

to prepare

to support

and verify

operations,

operational

the reuse

a means

continues

into flight

and their

14.3.1.4.2

capability.

deuterium

to future

MISSION

important

provides

missions,

Task

program

therefore

activated

systems.

can be

FUSION

program

14.3.1.5

duration

FLIGHT

material

mission

TASKS

product

is sent

identify

testing

STEP-

FIFTH

simply

TASK

14-24

base

LIFE

AND

flight

ERA

This

THE

both

data

long

This

3He

and

The

and

test

the

are

the

will

for

(A)

for

(C)

and

energy

FLIGHT

FUSION

in fusion

a sample

such as,

suggested

to expand

technology

the safety

of science,

A suggested

14.3.1 *5.1

for example,

as no other

(A). SPACE

OPERATIONS

can otherwise

enhancements.

is conservatively

14.0 Recommended

and for ultimately

Space Fusion Strategy

(B) manufacturing/production

the fleet size and capability,

its flight not be the of

for enhancing source

flight program mission scenario

here is ultimately that

the safe conduct is particularly

energy of missions suited

of for return mission is provided

of Mars. The first space application as an unmanned mission

The major goal and interest for application accomplished. Manned Mars Mission making the possible the settlement fusion the conduct from Jupiter. Fig. 14.4.

experience, durations. flight for (~1.7 years) will to Mars offers the most expeditious method to allow space flight while Mars Mission, as a good It is

A reusable unmanned mission at key programmatic space Reuse qualification. more than adequately (~0.5 years). the earliest obtaining multiple application an intermediate experience

the Manned are it was included as the third mission in this step.

of a Jupiter mission the system for a manned

to power the Manned Mars Mission

power operational flight mission

(~4 years) duration missions.

for an level will provide

flight operational return

That approach use of

environmental is considered

Multiple Asteroid Visits and Sample Return

energy following visits

by providing and longer

The flight duration

duration mission

data. science

fusion Next,

fusion missions.

for manned

Moon Sample Return

advantages

to build-up

appropriate

exposures,

anticipated

A science

for fusion;

designed

to take

Fig. 14.4.

possible

asteroid

Manned Mars

science

mission

sample

reactor

Pluto Sample

engine

course

qualify

longer

rocket

14-25

flight

over

Initial

Jupiter

the

Return

I !

[

for

__=1

i.e.,

flight.

reviews

systems

obviously

to space

purposes,

community

of science

the fusion

infrastructure

to accomplish

It is the last of

14.0 Recommended

Space Fusion Strategy

be the best source

require a significantly

missions for bringing

the planets to be explored.

and subsequent would

are typical, the application

to The system in Fig.

for planning of high energy

time for non-fusion reach of current

appropriate approach transportation

and to observe The priorities

That mission would powered propulsion

to be accomplished. engine is illustrated

undertaken. flight and is out of

mission to Pluto could be subsequently longer otherwise flight technology.

Those missions the potential science mission workshop among the science the most determine suggested operational into the NASA space 14.5.

program to to build up reduced mass but one in the fusion a clear

phase the means of is increased

A need exists conduct the space systems. operational

fusion This is a distinct program activity,

In the operational Also, continued. during era. this requirements.

of the production for the 50-80 MW vehicle to support

research and development, fleet,

under a separate to maintain technology,

fusion is completed the mission

the manufacture size

and to design new advanced,

fusion propulsion space infrastructure.

(B). MANUFACTURING

the technology

TECHNOLOGY

is identified

to maintain

era, which

to continue

SAMPLE RETURN JUPITER MOON

separately

PLUTO SAMPLE RETURN

The fleet

14.3.1.5.2

14.3.1.5.3

-,,,,

MULTIPLE ASTEROID

FUSION

Fig. 14.5.

SPACE

VISITS/SAMPLE

14-26

Initial

(C).

fuel

MANNED

RETURN

MARS

]

the

out

the

two

can

and

The

size

task

than

flight

AND

large

need

when

rather

fusion

space

fusion

stage.

herein

14.3.2

energy

interest

defined

warrant

interpret

initiation

guesses

gigawatt

between

reactors,

to point

objective

program.

identified

educated

to make

available.

need for

be made

separation

operations

the main

worthwhile

Production

this early

conversion

technology

has been

separately.

and small

PROGRAM

perspective,

It appeared

DEFINITION

consequently

4, continues.

development.

SCHEDULES

for example.

an indication

an extensive

be budgeted

and to point

the immediate

the availability

of a separate

the fuel, Task

energy ground

From a user’s

R & D program

14.0 Recommended

from NASA staff.

is in understanding

questions should

should develops

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