AFRPL TR-83-039 Phase I Report for the period 3 March 1983 to 23 May 1983 ALTERNATE PROPULSION ENERGY SOURCES June 1983 Author: Robert L. Forward, PhD, Consultant 34 Carriage Square, Oxnard, CA 93030 Contract: F04611-83-C-0013 Prepared for: Air Force Rocket Propulsion Laboratory, Air Force Space Technology Center, Space Division, Air Force Systems Command, Edwards Air Force Base, California 93523. Approved for Public Release; Distribution Unlimited. Abstract: This report summarizes the results of the first phase of the referenced contract. The task was to survey the entire field of advanced propulsion to uncover and carry out a technical assessment of any concept that showed promise of leading to a major advance in available energy sources for space power and propulsion in the next century. In general we were to consider any concept that might derive energy from the space environment, as well as any unconventional methods of storing energy in a compact form that may have applicability to space power and propulsion. The best of these were to be selected for investigation in Phase 2 of the contract. We uncovered 62 concepts, carried out technical assessments on 26 of the more promising concepts, and recommended that four concepts be considered for more detailed study in Phase 2: solid metastable helium, solar pumped plasmas, perforated solar sails, and antiproton annihilation propulsion. Of these, the Air Force selected two concepts to receive the major portion of the Phase 2 effort: solar pumped plasmas and antiproton annihilation. The Phase 1 activities were defined by the Statement of Work: Phase 1: Technical Assessment "The contractor shall conduct a thorough literature search and carry out an intense technical assessment of the latest concepts in science and engineering that show promise of leading to a major advance in available energy sources for space power and propulsion in the next century. In general, the contractor shall study any physical concept that might derive energy from the space environment, as well as any unconventional methods of storing energy in a compact form that may have applicability to space power and propulsion. The best of these shall be investigated in Phase 2." A literature search combined with a large number of personal contacts with people involved in the field of advanced propulsion insured that as many new concepts as possible were uncovered. Although some time was spent on detailed analysis when the concept warranted it, most of the activities in Phase 1 were of the data collection type rather than data analysis. The ten weeks of the Phase 1 technical effort involved writing 71 letters, taking 7 trips, interviewing 62 people, visiting 17 facilities, giving 7 lectures to a total of 350 people, and reading uncounted numbers of reports, papers, and other documents. This effort resulted in the uncovering of 62 propulsion energy concepts, of which 26 were well defined enough to allow a technical assessment. Facilities visited included Princeton University, MIT, JPL, Lawrence Livermore National Laboratory, Hughes Research Laboratories, Rockwell Space Systems Division, R&D Associates, United Technologies Research Center, G-T Devices, BDM Corporation, AFOSR, NASA/Lewis Research Center, Fermilab, and Caltech. Of the 26 concepts that received technical assessment in Phase 1, we recommended that four be considered for more detailed study in Phase 2: solid metastable helium, solar pumped plasmas, perforated solar sails, and antiproton annihilation propulsion. Of these, the Air Force selected two concepts to receive the major portion of the Phase 2 effort, solar pumped plasmas and antiproton annihilation. As time permits, studies are to also continue on free radical hydrogen, quantum dynamic energy, and ionospheric lasing. Phase 2: Concept Definition "The contractor shall identify the problems that still exist in making the selected concepts feasible, and identify the people or groups of people that can best analyze and propose solutions for those remaining problems. The contractor shall then assemble that team of investigators to attack the remaining problems in the selected technologies and put together a program plan that will be proposed to the Air Force Rocket Propulsion Laboratory. This program plan will outline the steps required for full development of the selected concepts." Concepts Receiving Preliminary Technical Assessment: - Metallic Hydrogen - Free-Radical Hydrogen - Metastable Helium - Mass Drivers / Rail Guns - Lightweight Lenses and Collectors - Solar Pumped Plasmas - Beamed Microwave Thrusters - Ionospheric Laser - Laser Heated Thrusters - Laser Electric Thrusters - Solar Sails - Perforated Light Sails - Laser Sails - Microwave Sails - Tether Power Systems - Tether Propulsion - Dynamic Structures (Launch Loop, Skyhooks) - High Temperature Radiators - Nuclear Fission Pulse - Imploded Micropellet Fusion - Monopole Catalyzed Fusion - Quark Catalyzed Fusion - Muon Catalyzed Fusion - Ultracold Neutron Fission - Metastable Excited Nuclei (Gamma Rays) - Antiproton Annihilation Concepts Uncovered That Did Not Receive Preliminary Technical Assessment (insufficient hard evidence or violate conservation laws): - Negative matter, Antigravity, Gravity shielding, Space warps, Time machines, Spin annihilation drive, Momentum annihilation drive, Inertia cancellation drive, Microwave phase drive, Oscillating proton drive, Water flow drive, Electromagnetohydrodynamic drive, Hyperfield resonance drive/warp, Unbalanced rotor (Dean) drive, Tachyons, Black hole thermal energy source, Alfvén propulsion, Fission fragment rocket, Radioisotope sail, Stimulated K capture, Solar heat collector prime power, Flywheels, Fusion ramjet, Psychokinetics (PK), Induced dipole microwave thruster, Rotary launcher, Scissors launcher, High speed pellet beam, Magnetic levitator, Cold-gas turbine thruster, Cryogenic oscillator. - Chemical Rockets Theoretical Limit: Conventional liquid oxygen/liquid hydrogen engines operate near theoretical limits (Isp ~ 460 s test stand, 528 s ideal). Advanced exotics include metallic hydrogen (Isp ~ 1700 s), atomic/free-radical hydrogen H + H -> H2 (Isp ~ 2130 s), and metastable helium He* -> He (Isp ~ 3150 s). - Metallic Hydrogen: Postulated density 1.15 g/cm3; theoretical calculations suggest production requires 1.9 to 5.6 Mbars. Recommendation: Wait for new high-pressure machine concepts capable of megabar pressures. - Free-Radical Hydrogen: Storing H atoms in high concentrations remains challenging due to recombination lifetimes. Recommendation: Monitor fusion-related spin-polarized hydrogen research. - Metastable Helium: Electronic excited state He(2 3S1) yields 19.8 eV per atom (114 kcal/gm), giving theoretical ideal Isp = 3150 s. Dr. Jonas Zmuidzinas (JPL) proposed techniques including ferromagnetic solid phases (He IV) and coherent laser optical pumping to suppress spin-orbit decay and extend lifetimes up to years. Recommended for Phase 2 study. - Solar Sustained Plasmas: Concentrated sunlight absorbed by alkali vapors (cesium, potassium) heated up to 3000 K can drive closed-cycle MHD electric generators, high-power lasers, or rocket thrusters (Isp > 1000 s). Recommended for Phase 2. - Lightweight Optics and Beamed Propulsion: Fresnel lenses (O'Meara para-lens), holograms, and laser-heated or laser-electric thrusters provide mass-efficient beaming options. - Perforated Solar Sails: Micro-perforating thin aluminum films (sub-micron holes) maintains reflectivity while significantly reducing mass and molecular drag in LEO, enabling rapid transit to GEO and polar levitated geostationary 'statite' orbits. Recommended for Phase 2. - Microwave Sails: Ultra-light fine-wire mesh lightsails (Starwisp probe, Freeman Dyson concepts) driven by gigawatt-scale microwave beams for rapid interstellar flybys. - Tether Systems and Dynamic Structures: Electrodynamic tethers for power/momentum exchange, rotating tether slings, and dynamic structures like Lofstrom's Launch Loop and dynamic skyhooks. - Imploded Micropellet Fusion: Laser, ion, or electron-beam driven D-T pellet microexplosions directed by magnetic nozzles. - Catalyzed Reactions: Monopole catalysis, fractionally charged particles (quarks), and muon-catalyzed fusion (measurements at LANL showing multiple catalyzed reactions per muon). - Ultracold Neutrons & Metastable Isomers: Coherent storage of cold neutrons and isomeric nuclear states for gamma-ray emission. - Antiproton Annihilation Propulsion: Proton-antiproton annihilation releases charged pions (decaying to muons, electrons/positrons, and neutrinos) and neutral pions (decaying to gamma rays). Charged reaction products can be directed by superconducting magnetic nozzles (Isp up to relativistic fractions of c). Key bottlenecks include low production and collection efficiencies at facilities like CERN and Fermilab, beam cooling, antihydrogen formation, and condensed antimatter storage (electrostatic suspension of antihydrogen ice). Strongly recommended for Phase 2 concept definition.