THE PONTIFICAL ACADEMY OF SCIENCES Study Week on Astrobiology 6-10 November 2009 • Casina Pio IV Introduction p. 3 • Program p. 5 • Abstracts p. 9 • Biographies of Participants p. 15 • List of Participants p. 21 • Memorandum p. 23 PONTIFICIA ACADEMIA SCIENTIARVM VATICAN CITY 2009 Beyond its historical dimension, this mystery of salvation also has a cosmic dimension: Christ is the sun of grace who, with his life, ‘transfigures and enflames the expectant universe’ (cf. Liturgy). The Christmas festivity is placed within and linked to the winter solstice when, in the northern hemisphere, the days begin once again to lengthen. In this regard perhaps not everyone knows that in St Peter's Square there is also a meridian; in fact, the great obelisk casts its shadow in a line that runs along the paving stones toward the fountain beneath this window and in these days, the shadow is at its longest of the year. This reminds us of the role of astronomy in setting the times of prayer. The Angelus, for example, is recited in the morning, at noon and in the evening, and clocks were regulated by the meridian which in ancient times made it possible to know the ‘exact midday’. The fact that the winter solstice occurs exactly today, 21 December, and at this very time, offers me the opportunity to greet all those who will be taking part in various capacities in the initiatives for the World Year of Astronomy, 2009, established on the fourth centenary of Galileo Galilei's first observations by telescope. Among my Predecessors of venerable memory there were some who studied this science, such as Sylvester II who taught it, Gregory XIII to whom we owe our calendar, and St Pius X who knew how to build sundials. If the heavens, according to the Psalmist's beautiful words, ‘are telling the glory of God’ (Ps 19[18]: 1), the laws of nature which over the course of centuries many men and women of science have enabled us to understand better are a great incentive to contemplate the works of the Lord with gratitude. Benedict XVI, Angelus, St Peter’s Square, Fourth Sunday of Advent, 21 December 2008 INTRODUCTION Prof. JONATHAN I. LUNINE, chair of the Scientific Organizing Committee Dr. JOSÉ G. FUNES, S.J., Director of the Vatican Observatory Study Week on Astrobiology Astrobiology is the study of life’s relationship to the rest of the cosmos: its major themes include the origin of life and its precursor materials, the evolution of life on Earth, its future prospects on and off the Earth, and the occurrence of life elsewhere. Behind each of these themes is a multidisciplinary set of questions involving physics, chemistry, biology, geology, astronomy, planetology, and other fields, each of which connects more or less strongly to the central questions of astrobiology. Stimulated by new capabilities for scientific exploration on and off the Earth, astrobiology seems to be establishing itself as a distinct scientific endeavor. The study of Astrobiology is a quite appropriate subject for the Pontifical Academy of Sciences which has a multi-disciplinary membership. The study week being undertaken by the Pontifical Academy of Sciences has an ambitious agenda: to bring together leading scientists in these diverse fields, to share the latest results of their own research and provide a broader perspective of how these results impact other areas of astrobiology. To accomplish these goals successfully will not be easy, because the language – really, to be honest, the jargon – of each of the fields represented by the speakers is not broadly understood. How does one explain to an astronomer the intricacies of chemical markers of biological activity in ancient Earth sediments? Or conversely, how can a molecular biologist be briefed with adequate depth on the latest astronomical techniques for detecting planets? The paradox of astrobiology is that, while one might regard it as a rather narrow and specialized endeavor, one cannot hope as an individual to adequately understand the span of traditional disciplines that form the backbone of the field. The study week, then, is very much a cross-disciplinary education for experts in one field to gain insight and understanding in other more distant disciplines – but always under the reasonably well-defined rubric of astrobiology. This is nothing new: for the 13 years that astrobiology has been recognized as a nascent field unto itself, scientists have been educating each other in an effort to understand one another’s fields. But oftentimes this comes in the environment of the frenetic ‘annual conference’, that phenomenon of modern scholarship in which the maximum number of talks is packed into the space of a few days, leading to a kind of intellectual bazaar in which scientists shop for nuggets of information (usually, for convenience, in their own discipline), check to make sure that competitors are not hawking the very wares they seek to proffer, or (rarely), venture forth into sessions outside of their own expertise, to puzzle over just what is being said. More focused workshops in astrobiology, as in other sciences, of course occur; but most often in one subfield. In any given month geologists might be meeting in Vancouver to pour in depth over the latest results on the most ancient appearance of fossils in the terrestrial rock record, while in Rio astronomers pour over new data on the abundance of the life-forming elements in nearby star-forming regions, and in Potsdam planetary scientists discuss the latest evidence for life occurring beneath the oxidizing surface of Mars. The present study week is not a unique event, but it is a relatively rare one. A focused week in which (relatively) cloistered astrobiologists confront each other’s fields of research and try to understand them is a difficult but heady undertaking. To make this feasible in a practical amount of time, we have carefully selected speakers who can make their own particular fields of research understandable to astrobiologists from other fields, indeed even to the intelligent layman, and who can connect their research to the broader problems of astrophysics. The program is organized into eight sessions. Session 1, on The Origin of Life, concerns the difficult problem of the mechanisms by which molecules became organized in such a way as to permit life to begin. Life as we know it on Earth is built on a structure of proteins and nucleic acid polymers which carry the information to build the proteins from their constituent amino acids. While complex, life is a very specific and selective organic chemistry: out of the broad range of possible organic acids that abiotic systems can produce, life utilizes just a handful; likewise, life largely utilizes just left-handed amino acids and right handed sugars. There is much more to the biochemistry of life than this, but it is exemplary of the challenge chemists and biochemists face in understanding how the cacophony of abiotic organic chemistry evolved into the structured symphony of life. Likewise, teasing out of the scant geologic record of the early Earth some indication of the environmental conditions under which life formed is an extremely difficult task, because geologic activity – the forces of tectonics, erosion, impacts of asteroidal material – have largely erased the evidence of the Earth’s environment in its first half-billion years after formation. Session 2, Habitability Through Time, concerns the problem of how the Earth has been able to sustain life over its long geologic history. Here the geologic record is more ample than that during the time life is presumed to have begun (and, it should be made clear, we have no precise understanding of when that in fact occurred). But now the processes are more complex: a variety of scales of space, time and energy come into play. The Sun itself, which is often tacitly regarded as the stable sustainer of the liquid water essential for life as we know it, was approximately 30% less bright early in the Earth’s history than it is today. Yet geological evidence for liquid water on Earth’s surface when the Sun was so faint suggests that our atmosphere must have provided a much stronger greenhouse effect than, and been quite different from, that of today. Episodes of severe glaciation in the geologic record suggest that from time to time the atmospheric ‘thermostat’ failed. How life – even at the molecular level – and the environment have interacted over geologic time is the subject of Session 3, Environment and Genomes. Molecular signatures of the biochemical reactions sustaining life remain in the geologic record, giving us hints of the changes over vast periods of time. Lessons from life forms that live in extreme environments, such as submarine vents and the Earth’s driest deserts, aid the interpretation of this record. The relatively sudden appearance of animal life late in the Earth’s history remains a mystery whose solution might be found in both the environment of the time and the workings of the genome. Earth seems to be unique in our solar system in terms of its abundant life, and yet we cannot be sure that life is not present on Mars or elsewhere in the solar system. Session 4, Detecting Life Elsewhere, explores the prospects and techniques for finding life in a variety of environments elsewhere in the solar system, beyond Mars to the asteroids and the moons of Jupiter and Saturn. Whether or not life exists elsewhere within our own solar system, the vast Milky Way Galaxy of which we are a part contains over 100 billion stars. If planets are a common feature of such stars, might life be as well? The next three sessions explore in a systematic fashion the detection, formation, and properties of planets around other stars: ‘extrasolar planets’. Session 5, Search Strategies for Extrasolar Planets, explains the various techniques used to find planets around other stars and determine their properties. Already, about 380 extrasolar planets are known, and the number of stars searched suggests that at least 10% of stars similar in properties to our own Sun have at least one planet. Session 6, Formation of Extrasolar Planets, details progress in understanding how planets form as a part of the process of the formation of stars. Two outstanding questions are what determines when a rocky planet like the Earth will form versus a gas giant like Jupiter, and is the process of planet formation materially different around stars much smaller than our Sun. Finally, Session 7, Properties of Extrasolar Planets, brings to bear computer modeling, astronomical data and a bit of speculation on the question of the properties of extrasolar planets as a function of the properties of, and distances from, their parent stars. Ultimately, much of the fascination of astrobiology comes from the question of whether sentient life forms exist on other worlds, and whether forms of life alien to our own in fact coexist with us – today – on our own home world. Session 8, Intelligence Elsewhere and Shadow Life, explores both these issues. The search for intelligent life elsewhere is being conducted by listening to the cosmos with radio telescopes in an effort to pick up a signal of inarguably artificial origin. A search for life with a biochemistry different from that of all the known life on Earth – what has been termed ‘shadow life’ – on our own planet is a fascinating possibility but one fraught with daunting difficulties. Astrobiology is an effort to use a diverse range of scientific techniques, focused on targets from the molecules in cells to the vast cosmos around us, to provide a deeper appreciation of humankind’s place in the cosmos. It is a recognition of the remarkable intricacies of all that is within and around us and a 21st century realization of the psalmist’s recommendation (Ps 111:2) to delight in its study. PROGRAM FRIDAY, 6 NOVEMBER 2009 9:00 Word of Welcome, and Greeting by the Holy Father — H.Em. Card. Giovanni Lajolo 9:20 Outstanding Questions in Astrobiology — J.I. Lunine SESSION 1 • ORIGIN OF LIFE (Chair J.I. Lunine) 10:00 Kinetics, Catalysis, and the Origin of Metabolism — S.D. Copley 10:40 Coffee break 11:10 Towards a Theory of Life — S. Benner 11:50 The Geological Record of Early Life on Earth (and its Limitations) — F. Westall 12:30 Discussion on Session 1 — J.I. Lunine (lead) 13:10 Lunch at the Casina Pio IV SESSION 2: HABITABILITY THROUGH TIME (Chair E.J. Gaidos) 14:50 The Earliest Earth’s Atmosphere — F. Selsis 15:30 Evolution of Earth’s Atmosphere and Climate — J.F. Kasting 16:10 Snowball Earth: Causes, Occurrences & Habitability — J.L. Kirschvink 16:50 Coffee break 17:20 Discussion on Session 2 — E.J. Gaidos (lead) SESSION 3: ENVIRONMENT AND GENOMES (Chair F. Westall) 18:00 Life & Environment in Earth’s Middle Age — A.H. Knoll 18:40 Molecular Signatures of Life Through Time — R.E. Summons 19:20 Dinner at the Casina Pio IV SATURDAY, 7 NOVEMBER 2009 9:00 Submarine Hydrothermal Vents: Limits of Life, Early Evolution and the Search for Habitable Planets — J. Baross 9:40 Conditions During the Emergence of Animal Life — E.J. Gaidos 10:20 Coffee break 10:50 The Atacama Desert as an Analog Model for Mars — R. Vicuña 11:30 Discussion on Session 3 — F. Westall (lead) SESSION 4 • DETECTING LIFE ELSEWHERE (Chair A.H. Knoll) 12:10 Europa: Next Destination in the Search for Life — M. Blanc 12:50 Lunch at the Casina Pio IV 14:50 Titan and Enceladus: Astrobiological Analogs with Earth — A. Coustenis 15:40 Life in Water-Rich Asteroids? — J.C. Castillo-Rogez 16:20 Early Mars: Cradle or Coffin? — R. Pierrehumbert 17:00 Coffee break 17:30 Discussion on Session 4 — A.H. Knoll (lead) 18:10 Briefing on Proceedings Volume — J.G. Funes/C. Impey 19:00 Dinner at the Casina Pio IV SUNDAY, 8 NOVEMBER 2009 7:00 Bus leaves Domus Sanctae Marthae on pilgrimage to Assisi 12:00 Holy Mass at the Basilica of St Francis in Assisi celebrated by H.Em. Card. Giovanni Lajolo 13:30 Lunch at Assisi 21:00 Dinner at the Casina Pio IV MONDAY, 9 NOVEMBER 2009 SESSION 5 • SEARCH STRATEGIES FOR EXTRASOLAR PLANETS (Chair C. Impey) 9:20 Search and Characterization Strategies — S. Seager 10:10 Review of Detected Low Mass Planets — C. Lovis 10:50 Coffee break 11:20 Study of Exoplanet Atmospheres and the Small Star Opportunity — D. Charbonneau 12:00 Low-Mass Planets Around Faint Nearby Dwarf Stars — D. Minniti 12:30 Discussion on Session 5 — C. Impey (lead) 13:10 Lunch at the Casina Pio IV SESSION 6 • FORMATION OF EXTRASOLAR PLANETS (Chair D. Minniti) 14:40 Formation of Giant Planets — W. Benz 15:10 Formation of Earth-Sized Planets — S.N. Raymond 15:50 Discussion on Session 6 — D. Minniti (lead) 16:30 Coffee break SESSION 7 • PROPERTIES OF EXTRASOLAR PLANETS (Chair R.T. Pierrehumbert) 17:00 Characterising Exoplanet Atmospheres, from Gas Giants to Terrestrial Habitable Planets — G. Tinetti 17:30 Habitability of Exoplanets — D.D. Sasselov 18:10 Discussion on Session 7 — R.T. Pierrehumbert (lead) 19:30 Dinner at the Casina Pio IV TUESDAY, 10 NOVEMBER 2009 9:00 Work on the Summary Statement — J. Lunine SESSION 8 • INTELLIGENCE ELSEWHERE AND SHADOW LIFE (Chair S.A. Benner) 9:30 Reflections on the Future of Astrobiology — C. Impey 10:10 SETI Turns 50 — J.C. Tarter 10:50 Coffee break 11:30 Searching for Multiple Origins of Life — P. Davies 12:10 Discussion on Session 8 — J.F. Kasting (lead) 13:00 Lunch at the Casina Pio IV ABSTRACTS Submarine Hydrothermal Vents: Limits of Life, Early Evolution and the Search for Habitable Planets JOHN BAROSS The two types of hydrothermal vent environments, magma-driven and peridotite-hosted, offer many contrasting habitat conditions for microbial communities. These environments span a wide range of chemical and physical conditions that include almost all of the extremes in temperature, Eh, salinity and heavy metal concentrations that limit where life can exist. Moreover, vent microorganisms have adapted to habitat conditions that include flowing fluids, porous spaces within basalt, sulfides and sediments, the surfaces of rocks and animals and the subseafloor potentially to depths in the crust exceeding 6 km. Hydrothermal systems produce volatiles, such as H2, H2S, CH4, CO, CO2, and trace metals that are important sources of carbon and energy, and nutrients for organisms. The sources of volatiles include magma degassing, water/rock reactions, and abiotic reduction of CO2 to methane and possibly other organic compounds. All of these reactions take place in the subseafloor and are not always dramatically expressed on the seafloor. Recently, a peridotite-hosted hydrothermal vent environment was discovered on the Mid-Atlantic Ridge. This environment, named the ‘Lost City Hydrothermal Field’ is a source of high concentrations of hydrogen and methane and organic acids and hydrocarbons produced abiotically from serpentinization reactions that take place in the crust. Hallmark characteristics of both types of high temperature hydrothermal vent microbial communities are that they utilize hydrogen as a primary energy source and they exist as biofilms. This is interesting in that there are parallels between the energy metabolic reactions of these microbial biofilms and the chemistry of the H2-CO2 redox couple that are present in hydrothermal systems, thus indicating the possibility that vent autotrophy might provide clues about the kinds of reactions that initiated the chemistry of life. Moreover, an argument can be made that obtaining evidence for active tectonics and hydrothermal activity on any planetary body (presently or in the past), mechanisms that are vital for extracting life-supporting volatiles and elements from rocks and creating diverse environmental settings, would increase the probability for its ability to support life. Towards a Theory of Life STEVEN A. BENNER One of the most reductionist definition-theories for life holds that it is a self-sustaining chemical system capable of Darwinian evolution. While this has been advanced as a universal definition-theory, it is clearly Earth-centric, as it conforms closely to the features of the terran life that we know. This talk will survey four general approaches that have exploited this definition in the Benner laboratory to understand the concept of ‘life’ as a universal, assessing its likely form and distribution in the cosmos. The first works backwards in time from modern life, using biotechnology to resurrect ancient genes and proteins for study in the laboratory. Another works forward in time, starting with simple organic molecules that are formed without life, to ask how these might have self-assembled to give the first living systems. The third considers ‘weird’ environments in the solar system, those that deviate significantly from those on Earth that hold terran life. The last involves synthesis, where self-replicating Darwinian systems are constructed artificially to see what emergent properties in biology they can yield. Together, these four approaches are constraining the ‘black box’ that capture the phenomenon of ‘life’ according to current reductionist theories of life to understand the potential and limitations of such simple models. The Formation of Giant Planets WILLY BENZ Since the discovery in 1995 of the first planet outside the solar system by the Swiss astronomers Michel Mayor and Didier Queloz, over 350 exoplanets have now been found. While most of them are giant planets, stunning improvements in the detection techniques allows today the discovery of planets only a few times more massive than the Earth. With increasing numbers, the population of exoplanets begins to provide strong constraint to planet formation models. Quantitative comparisons between observations and theoretical calculations are becoming possible through a population synthesis approach. Such comparisons allow identifying the major uncertainties and their observational consequences. In this talk, I will briefly review the recent progress in the theory of giant planet formation and pinpoint these major uncertainties. In addition, I will stress the importance of considering the formation of giant and terrestrial planets simultaneously and self-consistently. Europa: Next Destination in the Search for Life MICHEL BLANC The exploration of the Jovian System and its fascinating satellite Europa is one of the priorities presented in ESA’s ‘Cosmic Vision’ strategic document. The Jovian System indeed displays many facets. It is a small planetary system in its own right, built-up out of the mixture of gas and icy material that was present in the external region of the solar nebula. Through a complex history of accretion, internal differentiation and dynamic interaction, a very unique satellite system formed, in which three of the four Galilean satellites, Europa, Ganymede and Callisto are locked in the so-called Laplace resonance. The energy and angular momentum they exchange among themselves and with Jupiter contribute to various degrees to the internal heating sources of the satellites. While all three are likely to host sub-surface oceans, only Europa’s ocean is believed to extend between its geodynamically active icy crust and its silicate mantle, possibly providing the main conditions for habitability. For this very reason, Europa is one of the best candidates for the search for life in our Solar System. We will review our current understanding of how these habitability conditions may be fulfilled at Europa, and what measurements need to be performed there with a dedicated mission to Europa. To understand in a more generic way habitability conditions around giant planets, we also need to go beyond Europa itself and address two more general questions at the scale of the Jupiter system: to what extent is its possible habitability related to the initial conditions and formation scenario of the Jovian satellites? To what extent is it due to the way the Jupiter system works? For these reasons NASA and ESA are embarking on a joint mission to the Jupiter system, involving an orbiter of Europa and an orbiter around Ganymede, the largest moon in the solar system. Pending final selection in the ESA Cosmic Vision implementation process, the mission would launch in 2020, some three years after the anticipated completion of Cassini. Life in Water-Rich Asteroids? JULIE C. CASTILLO-ROGEZ Large, low-density C-type asteroids are abundant in the main belt. The most prominent of these objects is the dwarf planet Ceres, which presents an advanced stage of evolution. Ceres is almost twice as large as Enceladus, and both objects contain more than 50% of water in volume. Although asteroids cannot benefit from tidal heating like outer planet satellites, their proximity to the Sun warrants an everlasting supply of energy. Observations with the Hubble Space Telescope and geophysical modeling indicate that Ceres is likely to be differentiated. Besides, warm surface temperatures may promote the preservation of a deep liquid layer, if the water shell contains second-phase volatile impurities and hydrated minerals. Indeed, even if Ceres were ‘frozen’, i.e., its interior were in thermal equilibrium with its surface, then its internal temperature would still reach at least 180 K in low-latitude regions. These conditions offer a context suitable to endogenic activity involving the exchange of material between the interior and the surface. Recent ground-based observations indicate the presence of brucite and magnesite at the surface of Ceres, the signature of pervasive hydrothermal alteration whose origin, surficial or due to internal processes, remains to be understood. The many questions raised by astronomical observations of Ceres will hopefully be answered by the Dawn Mission that will visit the protoplanet in 2015. The Dawn Mission is instrumented with the capability to measure composition and constrain internal properties and geological evolution. This information will help better assess the astrobiological potential of the dwarf planet. Other, large C-type asteroids may also harbor habitable conditions as a result of warm surface temperature. We will review the main characteristics of these protoplanets, discuss possible formation scenarios for these objects, address their genetic link to meteorites, and discuss their habitability potential. We will also present ongoing plans for the future exploration of these objects and the techniques that can be used for constraining their internal structure and habitability. The Study of Exoplanet Atmospheres and the Small Star Opportunity DAVID CHARBONNEAU When exoplanets are observed to transit their parent stars, we are granted direct estimates of their masses and radii, permitting us in turn to infer a bulk composition and a likely formation history. Perhaps most intriguingly, transiting planets also afford studies of their atmospheres, both through the study of starlight transmitted during transit, and through the modulation of infrared emission when the planet disappears behind its parent star during an event known as secondary eclipse. In the past decade, these methods have yielded stunning advances in our understanding of gas giant exoplanets and their atmospheres. Yet it is only during the last months of 2009 that astronomers have uncovered the first transiting examples of much smaller bodies composed primarily of rock and ice. Should we succeed in finding examples of such planets in the habitable zones of low-mass stars, then we could undertake the study of their atmospheres in the next 5 years and jumpstart our hunt for biomarkers in the atmosphere enshrouding a world orbiting another star. Kinetics, Catalysis and the Origin of Metabolism SHELLEY D. COPLEY Catalysts are essential for life; nearly every reaction that occurs in extant cells is catalyzed by an enzyme. Catalysts must have been essential for the emergence of life, as well, enabling a proto-metabolic network that supplied the precursors of macromolecules. Early catalysts such as minerals and small molecules would likely have been inefficient relative to the prodigious enzymes of today, but still important for accelerating rates of useful reactions. Although the importance of rate acceleration by catalysts is obvious, a less-appreciated role for early catalysts would have been to prune complex proto-metabolic networks by channeling molecules through particular pathways and thereby allowing accumulation of higher concentrations of a few components, rather than low concentrations of many components. This principle will be illustrated by experiments showing that pyruvate is converted to different products by different minerals found in hydrothermal vents. These results suggest that mapping of catalytic reactivity space with respect to mineral type, small molecules, temperature, and pH is needed to delineate the various microenvironments that may have contributed to proto-metabolism and the suite of molecules available for life. A model for how early catalysts may have promoted the emergence of the RNA World will also be discussed. Titan and Enceladus: Astrobiological Analogs with Earth ATHENA COUSTENIS Titan is currently the only confirmed exobiotic environment known to us. It is also perhaps the most intriguing object in our Solar System. Our understanding of Titan, and of its kronian sibling Enceladus, has been greatly enhanced by the data returned by the Cassini-Huygens mission since 2004 and still operating on the spot. Thus, we know today that the thick atmosphere layer – covering the satellite’s mysterious surface – is essentially made of nitrogen, with small amounts of methane and hydrogen. The combination among these mother molecules produces an exciting organic chemistry in Titan’s atmosphere, with hydrocarbons and nitriles (one of the latter, HCN, is a prebiotic molecule). The organic chemistry, climate conditions, meteorology, methane cycle and other aspects of the surface make Titan an extremely important astrobiological place. Similarly, a strong bioastronomical potential is afforded by Enceladus who is surrounded by an atmosphere created by water ice and organics ejections coming from the interior. I will discuss our current understanding of the astrobiological aspects of the two satellites as inferred from current and past observations. After the Cassini-Huygens mission, there will remain several unanswered questions on the astrobiological aspects of the satellites which will require a future mission with an optimized orbital tour, specific in situ elements and advanced instrumentation, such as the Titan Saturn System Mission studied in 2008. Searching for Multiple Origins of Life PAUL DAVIES Astrobiologists are aware that extraterrestrial life might differ fundamentally from known life, and considerable thought has been given to possible signatures that might attach to weird forms of life on other planets. So far, however, very little attention has been paid to the possibility that our own planet might also host microbial communities of weird life – that is, life as we do not know it. If life arises readily in earthlike conditions, as many astrobiologists contend, then it may well have started many times on Earth itself, raising the question of whether one or more shadow terrestrial biospheres of alternative life forms have existed in the past, or still exist today. The issue is critical to the question of whether or not we are alone in the universe, because if life has started from scratch many times on Earth, it is likely also to have started on many earthlike planets. In my talk I shall discuss possible signatures of weird life, and outline some simple strategies for seeking evidence of a shadow biosphere. Conditions During the Emergence of Animal Life ERIC J. GAIDOS Animal life emerged in the late Precambrian before 540 million years ago (Ma), and perhaps as early as ca. 600 Ma. This pivotal event was accompanied by low-latitude glaciations and large excursions in the isotopic composition of inorganic carbon in surface waters. It was preceded by a long interval in which the deep ocean was sulfidic and the concentration of oxygen in the atmosphere was well below the modern value. The link between oxygenation of the oceans and the appearance of animals in the fossil record is widely accepted, but the causal relationships between marine biogeochemical cycles, climate, and atmospheric composition are controversial. I describe how high marine sulfide might have maintained low oxygen, high methane, and declining carbon dioxide (CO2) in the Precambrian atmosphere, and how Earth may have escaped from this condition only when low CO2 and marine bicarbonate (HCO3-) triggered a ‘biotic crisis’ near the end of the Precambrian. The tempo of planetary change depended on the luminosity evolution of the Sun and the abundance of sulfur in magmas and volcanic gases, and may be different on planets around other stars. Reflections on the Future of Astrobiology CHRIS IMPEY Astrobiology is a young and exciting, interdisciplinary field of science. In a few decades, the terrestrial frontier has seen insights into the range of life on Earth and its origin, and the varied mechanisms by which life turns energy into information. Meanwhile, the extraterrestrial frontier has witnessed the discovery of about 400 exoplanets, some of which are nearly Earth-like, the identification of several habitable locations in the Solar System, and the use of new technology to search for extraterrestrial intelligence with increased sensitivity. The future of astrobiology will be most sharply defined by the discovery of life beyond Earth. History may not a good guide to the future, just as life on Earth may not be a good guide to the characteristics of biology elsewhere. It is of course possible that scientists’ optimism about the broad predisposition of the universe for life is misplaced, rendering biology rare and difficult to detect. Nonetheless, this talk will hazard guesses on how the subject may evolve and what the best research avenues might be to make the breakthrough discovery. Habitability of the Earth and Evolution of Its Atmosphere JAMES F. KASTING Earth is comfortably within the habitable zone of the Sun – the region where liquid water can exist on a planet’s surface – so it may not seem surprising that the Earth has remained habitable, and inhabited, throughout most or all of its recorded history. Solar luminosity has increased by 40 percent from its original value during that time, however, so a complex interplay of factors was needed to actually keep the planet fit for life. Chief amongst these factors was the negative feedback between atmospheric CO2 and climate provided by the carbonate-silicate cycle. All other things being equal, low surface temperatures on the early Earth would have led to slower rates of silicate weathering, and thus to buildup of volcanic CO2, which would have helped offset the lower temperatures by providing greenhouse warming. Models based on CO2 feedback alone, however, predict more CO2 than is consistent with various CO2 indicators, specifically paleosols and siderite banded iron-formations. This suggests that CH4 may have played a role, as well. The CH4 greenhouse effect is complicated, though, because too much CH4 can lead to formation of hydrocarbon haze, which creates an anti-greenhouse effect that can cool the planet. The details of how this haze forms and how it interacts with incident solar radiation are still being worked out. I will provide an update on where this modeling stands. I will also talk about the controversial O and Si isotopic evidence for hot Archean climates and how this evidence can be weighed against other climate indicators. Snowball Glaciation: Lessons for Habitability on Earth and Elsewhere JOSEPH L. KIRSCHVINK & TIMOTHY D. RAUB Earth’s glacial record has become more frequent but less severe as the planet has aged. Although many Precambrian glaciations supported sea ice in tropical to equatorial latitudes, well within a ‘Snowball Earth’ zone predicted by ice-albedo runaway in energy-balance models, it remains uncertain whether Precambrian interglacial Earth supported a polar ice mass. All Precambrian glaciations display geochemical evidence of syn- and post-glacial oxidation (Raub & Kirschvink, 2008). Beneath the modern Antarctic ozone hole, ultraviolet photochemical reactions trap frozen H2O2; this same process oxidizes icy moons like Europa and Enceladus. Prior to terrestrial atmospheric oxygenation, such ice-bound peroxides might reach parts-per-thousand levels, sufficient for oxidized meltwater to hypothetically force the original evolution of oxygen-mediating enzymes. As-yet unrecognized Archean polar ice caps might similarly account for ‘whiffs’ of trace oxygen (Anbar et al., 2007, Frei et al., 2009) without invoking the specter of oxygenic photosynthesis (Kirschvink & Kopp, 2008). If the accumulation of peroxide in polar glaciers is the only mechanism that can drive de novo evolution of molecular oxygen-mediating enzymes, there is an interesting implication for Astrobiology: Earth-like planets too close to their parent Star to form glaciers will probably never experience oxyatmoversion and will be unlikely to have animal life. Life and Environments in Earth’s Middle Age ANDREW H. KNOLL Astrobiological interest in Earth history commonly focuses on life’s first and most recent chapters, the origin of cells and the emergence of complex organisms. Much of Earth’s physical and biological history, however, played out during the long interval between these events, and it can be argued that both the nature and timing of animal evolution reflect the events of Earth’s middle age. The interval in question began with the initial rise of oxygen in surface oceans and environments, an event well documented in the rock record but imperfectly understood in terms of process. Increasingly, geochemical data suggest that the world that emerged from this transition was not our modern Earth, with oceans oxygenated from top to bottom, but, after ca. 1800 Ma, a long lasting intermediate state in which a moderately oxygenated atmosphere and surface ocean lay above by an oxygen minimum zone that tended toward euxinia. Paleontological data suggest that eukaryotic microorganisms populated the oceans during this interval, some of them with the capacity for simple multicellularity or cell differentiation. Nonetheless, both fossils and molecular biomarkers suggest that the diversity, complexity and ecological footprint of eukaryotes remained low until ca. 800 Ma. Emerging geochemical data suggest that this paleontologically observable blossoming of eukaryotic diversity corresponds not to a sharp increase in oxygen levels but rather to the statistical replacement of euxinic subsurface waters by ferruginous water masses. Latest Proterozoic oxygen increase does, however, correlate with the expansion of macroscopic animals, as well as red and green algae characterized by complex multicellularity. All complex multicellular organisms have active transport mechanisms for oxygen, signaling molecules and nutrients, circumventing the strong constraints imposed by diffusion. The chicken-and-egg problem of whether size increase reflects or promotes active transfer of molecules within organisms might be solved by considering the relationships among size, metabolism, and differentiation as a positive feedback loop, nudged in the right direction by late Neoproterozoic environmental change. Review of Detected Low-Mass Planets CHRISTOPHE LOVIS Since 2004, a new population of extrasolar planets, having masses below 20-25 Earth masses, has been emerging from planet-search surveys. This has become possible thanks to important progress in the planet detection sensitivity of the two main observational techniques currently dominating the field: high-precision radial velocities and transit photometry. In the Neptune mass regime and below, hydrogen is probably not the main constituent of planets any more, but is replaced in this role by ices and rocks. The recent discoveries are therefore unveiling for the first time a population of ‘solid’ planets, although most of their properties remain to be explored. In this presentation I will review several examples of low-mass planets and planetary systems, and discuss some of their orbital and physical characteristics. First guesses regarding their overall abundance in our Galaxy can also be made. I will conclude with the prospects of detecting habitable planets, with a mass similar to the Earth and located at the appropriate distance from their parent star, in the near future. Outstanding Problems in Astrobiology JONATHAN I. LUNINE Astrobiology is the study of life as a cosmic phenomenon: its major themes include the origin of life and its precursor materials, the evolution of life on Earth, its future prospects on and off the Earth, and the occurrence of life elsewhere. Behind each of these themes is a multidisciplinary set of questions involving physics, chemistry, biology, geology, astronomy, planetology, and other fields, each of which connects more or less strongly to the central questions of astrobiology. Stimulated by new capabilities for scientific exploration on and off the Earth, astrobiology seems to be establishing itself as a distinct scientific endeavor. The outstanding problems in astrobiology can be laid out schematically but conveniently in the form of an equation first written 50 years ago by Frank Drake. The equation enumerates the number ‘N’ of observable extraterrestrial civilizations in our Milky Way Galaxy as equal to R x fp x ne x fl x fi x fc x L, where R is the rate of formation of suitable stars (it is sufficient to assume those similar in mass and composition to the Sun) in our galaxy, fp the fraction of stars with planets, ne the average number of such planetary systems with a habitable, or life-sustaining, environment, fl the fraction of habitable planets on which life actually forms, fi the fraction of those life-bearing planets with intelligent life, fc the fraction of those intelligence-bearing planets with a civilization technically capable of transmitting signals, and L the average lifetime of such a civilization. The first three terms are known or in the process of being determined today by astronomical techniques on the ground and in space. The fourth term can be constrained by determining whether life – of independent origin from that on Earth – exists in habitable environments elsewhere in the solar system (Mars, Europa, Enceladus, Titan). The fifth term is more tenuously connected to data, but the history of life on Earth and the late onset of complex, intelligent beings has suggested to some that while primitive life might be common, intelligent life could be a rare phenomenon in the cosmos. Low-Mass Planets Around Faint Nearby Dwarf Stars DANTE MINNITI There has been great progress in the search and characterization of extrasolar planets. In particular, current searches are focussing on planets less massive than Neptune orbiting nearby dwarf stars. A few of these systems are already known, and it is expected that some transiting low mass planets will become available in the next few years. I will describe SIMPLE, a new high-resolution near-IR spectrograph for the E-ELT being build at Arcetri. SIMPLE is a canonical cross-dispersed Echelle spectrograph designed to have a resolving power of 100,000, covering from 0.8 to 2.5 microns in a single frame. SIMPLE at the E-ELT will allow to characterize the atmospheres for transiting low mass exoplanets, and also to search for potential atmospheric biomarkers. I will also describe our current Carnegie-Catolica search for extrasolar planets around nearby stars with the Magellan 6.5m telescope with MIKE, presenting the main results for the 11 exoplanets discovered so far. These are long period, massive planets orbiting generally in eccentric orbits. Future plans to extend the Magellan Planet Survey will be also discussed. Early Mars: Cradle or Cauldron RAYMOND T. PIERREHUMBERT There is abundant evidence that large quantities of liquid water existed at the surface of Mars very early in the planet’s history. This evidence takes the form of river-like features, surface mineralogy, and stratigraphy of the Noachian crust of the planet. One view of the climate of Early Mars holds that these features arise from eons-long periods of warm, wet equable climates, arising from an early massive atmosphere rich in greenhouse gases. Another holds that the climate consisted of long periods of frozen cold-dry climates followed by brief periods of hot torrential rains following giant impacts. I will review the basic physics underpinning both of these views, the implications for evolution of life, and the prospects for settling which is correct by further exploration of Mars. Mars is the archetype for the problem of determining the outer edge of habitable zones around stars. Generalizations of the Early Mars habitability problem, and applications to other planetary systems (notably about Gliese 581) will be discussed. Formation of Earth-Sized Planets SEAN N. RAYMOND Rocky (‘terrestrial’) planets are thought to form in a series of dynamical steps, starting from micron-sized dust grains in gaseous protoplanetary disks. During the last phase of growth, km-sized planetesimals and Moon-sized planetary embryos collide to form full-sized planets on a 100 million year timescale. It is during this phase that Earth’s final composition was determined by the composition of material within its feeding zone. A key question is the source of Earth’s water: the current leading theory is that the water was delivered via collisions with primordial asteroidal material. Extrapolating to planets around other stars requires an understanding of the dynamics of extra-solar planets – including orbital migration and planet-planet interactions – and their effect on terrestrial planet growth. I will discuss the prospects for water-rich Earth-like planets to exist in ‘hot Jupiter’ systems as well as in the known systems of extra-solar (giant) planets, many of which likely underwent dynamical instabilities. Search and Characterization Strategies for Habitable Worlds SARA SEAGER Fourteen years ago after the first discovery of exoplanets orbiting sun-like stars, few believed that exoplanet atmosphere observations were possible. Seven years ago, after the Hubble Space Telescope observation of the transiting HD 209458b atmosphere, many skeptics challenged it as a one-object, one-method success. With over two dozen exoplanet atmospheres observed today, we have solidly entered the first stage of exoplanet atmosphere research. I will briefly review the highlights of hot Jupiter atmosphere studies: detection of molecular spectral features; constraints on atmospheric vertical structure; and diversity of day-night temperature gradients. I will show what we can robustly infer from the two best transiting hot Jupiter atmosphere data sets: HD 189733b and HD 209458b, using a new atmospheric temperature and abundance retrieval method. As hot Jupiter observations and interpretation are maturing, the next frontier is super Earth atmospheres. Theoretical models are moving forward with observational hopes pinned on the James Webb Space Telescope, scheduled for launch in 2014. Further in the future lies realistic attempts to answer the enigmatic and ancient question, ‘Are we alone?’ via atmospheric biosignatures. Many of us are working hard to ensure we will have Earth analog targets for atmosphere observations in our life time. I will finish with a description of the lowest cost and nearest term chance we have for directly imaging Earth analog atmospheres: a space-based Terrestrial Planet Finder telescope that is a combination of the James Webb Space Telescope and a separately built and launched external occulter. Habitability of Exoplanets DIMITAR D. SASSELOV The talk will review planetary habitability from the aspect of observable features of exoplanets, which relate to planet structure, atmosphere, and specific global geochemical cycles. The Earliest Earth Atmosphere FRANCK SELSIS, ERIC HÉBRARD, ALESSANDRO MORBIDELLI, IGNASI RIBAS The early history of our planet is usually presented as the succession of two periods. During the first one, the Hadean, frequent catastrophic asteroids/comets impacts maintained conditions preventing life, and even complex chemistry, from occurring on Earth. The end of the Hadean is generally dated around 3.9-3.8 Gyrs ago (Ga), when impact rates decreased to bearable values. It is only during the second period, the Archean, that living organisms are assumed to have been able to evolve and spread in Earth’s environment. As a matter of fact, the oldest – and debated – possible traces of life have been found at the very beginning of the Archean, around 3.8 Ga in the form of 12C-enriched sediments. In this picture, which represents the most accepted view (often given in academic textbooks), the physical and chemical conditions at the transition between Hadean and Archean are regarded as the relevant context for prebiotic chemistry and the origins of life. However, the standard model for the atmosphere of the Earth 3.9-3.8 Ga ago does not seem to produce complex organics at high enough a rate to sustain efficient prebiotic processes (unlike in the Urey-Miller experiment). Therefore, scientists often invoke an external delivery of asteroidal/cometary organics or a sub-surface production in hydrothermal vents. We would like here to revisit this scenario by considering a more recent view of the bombardment history. We will show that the Earth could have been habitable as early as the end of the planetary accretion around 4.4 Ga and that life could have survived a Late Heavy Bombardment event that occurred between 3.9 and 3.8 Ga. We will show how the conditions during the earliest habitable period of the Earth, when our planet was subjected to the irradiation of the young but active Sun, differ from the ones that are usually assumed for the context of the origins of life. We will then discuss the implications for prebiotic chemistry. Molecular Signatures of Life Through Time ROGER E. SUMMONS Fossil hydrocarbons are commonly interpreted as diagenetic products of biochemicals, and therefore as proxies for organisms and biosynthetic pathways that have existed in the past. They can be particularly informative about organisms that leave no visible fossil evidence of their prior existence. Further, since many organisms proliferate only under stringent environmental restrictions, the fossil hydrocarbons may also serve as indicators for those conditions. An example would be fossil pigments derived from green and purple sulfur bacteria, photosynthetic bacteria that use hydrogen sulfide as an electron donor, which serve as proxies for the presence of sulfide in the photic zone of ancient seas. Another example would be the biosynthetic pathway leading to sterols which requires molecular oxygen in several steps. Thus, the detection of fossil hydrocarbons with these carbon skeletons far back in Earth history has been used to infer the antiquity of oxygenic photosynthesis. This presentation will focus on two aspects of the geologic record of fossil hydrocarbons. Firstly, using data from petroleum through the ages we will examine the successions in ocean plankton. These results are informative about an evolving composition of marine algal groups though time and, in particular, the nature of photosynthetic communities accompanying extinction and radiation events at the end of the Proterozoic, Paleozoic and Mesozoic Eras. We also report our most recent results concerning the detection of indigenous steranes and triterpanes in sediments from the late Archean through studies of cores from the Pilbara Craton obtained through the NASA Archean Biosphere Drilling Project and the Agouron Institute drilling in the Kaapvaal Craton of South Africa. SETI Turns 50 JILL C. TARTER Since the publication of the first scientific paper on the Search for Extraterrestrial Intelligence in Nature in September of 1959, SETI has been capturing the imaginations of young and old, scientist and layperson, in cultures around the globe, and SETI has become an innovative, scientific exploration. Within the past few years we have lost the pioneering authors of the first SETI paper, but the radio astronomer who conducted the first SETI search is still active, and a new generation of researchers are slowly beginning to replace the old guard. SETI is now sheltered under the larger umbrella of astrobiology, but it is far from a risk-free enterprise. From a single narrowband channel receiver exploring two stars, the search capacity has increased by more than 14 orders of magnitude in 50 years and SETI is well positioned to continue taking advantage of exponential improvements in multiple technologies. SETI has endured a roller-coaster funding saga that has included both federal and private support, and no support at all. As a science it is confounded by the persistent public misperception that it has something to do with UFOs. This talk will trace the history, detail the current status, and forecast the future of SETI, while trying to make some guesses about technologies not yet invented and discussing the question – What if SETI succeeds? Characterising Exoplanet Atmospheres, from Gas Giants to Terrestrial Habitable Planets GIOVANNA TINETTI Half a century ago, Space Age began with the launching of the Sputnik. Now at the completion of a fairly detailed study of the planets of our own solar system, we are at the dawn of the Age of Exoplanets. More than 300 exoplanets, i.e. planets orbiting a star different from our Sun, are now known thanks to indirect detection techniques. In the first decade after their initial discovery in 1995 by Mayor and Queloz, the task was to find more and more of these astronomical bodies: the biggest, the smallest; the hottest, the coolest. In recent years, attention has switched from finding planets to characterising them. Among the variety of exoplanets discovered so far, special attention is devoted to those planets which transit their parent star. Most recent observations, in fact, have proved being possible to use the wavelength dependence of the reduction in the brightness of the central star as the planet passes in front to identify key chemical components in the planet’s atmosphere. Molecules such as water, methane, carbon monoxide and dioxide have already been detected in the atmospheres of hot, giant exoplanets with Hubble and Spitzer Space Telescopes or from the ground. These planets are unsuitable for life, but the next generation of space telescopes -the James Webb Space Telescope or other mission concepts entirely devoted to the observation of exoplanet atmospheres- will guarantee the characterisation of fainter targets, in particular telluric planets in the habitable zone of their parent star. The Atacama Desert as a Model Habitat in Astrobiology RAFAEL VICUÑA and ARMANDO AZÚA The search for life in the Universe relies on the thorough understanding of life as we know it. Although biased by the single example we find on Earth, lifeforms and the habitats they use in our planet provide us with helpful models for astrobiology focused questions. One of these models is the Atacama Desert, which is the driest and probably the oldest extant desert on Earth. To survive in the hyperarid conditions prevailing in the place, lifeforms have had to adapt to very low air humidity levels, an almost complete absence of rain events, highly saline soils and high solar radiation. Still, in spite of this adaptation process, the harsh environmental factors cause that parts of the Atacama Desert are almost devoid of microbial life. These characteristics have made Atacama Desert a prime analog model for the planet Mars and many research teams are conducting experiments on various astrobiologically oriented topics. Regions within this desert are intensively being used for testing of biosignature detecting instruments and robots to be flown in future space missions. Some sites are also being studied as analogs for understanding the origin of life on Earth. Our work is focused on the understanding of the molecular and physiological adaptations of extremophiles living in the Atacama Desert. More specifically, we are studying different habitats, from salt pans to caves, describing the diversity of microorganisms living in them and the micro-environmental parameters to which these microorganisms have adapted. In particular, we are interested in the study of the evolutionary adaptations that arose to cope with limiting water availability for photosynthesis in cyanobacteria and micro-algae. So far, we have found that even small changes in the microenvironmental landscape cause dramatic changes in biodiversity, suggesting that life-supporting places behave like evolutionary islands with accelerated rates of speciation. Our data also suggest that small changes in a few key parameters of the abiotic landscape can have huge impacts on the habitability of extreme environments, even in scales of centimeters. This patchiness of life spreading needs to be considered when looking for life elsewhere in the universe. Thus, unless the sampling procedures in a specific site are very well designed, a negative result in the search for biosignatures may not necessarily reflect absence of life. The geological record of early life on Earth (and its limitations) FRANCES WESTALL The geological record of early life on Earth is very patchy but what has been preserved provides us with a fascinating insight into the ecology of the primitive Earth. Destruction or severe alteration of the Earth’s earliest crust by plate tectonic activity and crustal processes limits the availability of well-preserved rocks, the oldest of which are younger than 3.5 billion years old (Ga), a billion years after the consolidation of the crust. Two areas of ancient crust are particularly well-preserved, the Barberton greenstone belt in eastern South Africa and the Pilbara greenstone belt in NW Australia. The traces left behind by primitive life forms in these rocks exhibit a remarkable level of evolution, as far as can be interpreted from the chemical, isotopic and morphological biosignatures. The information provided by these biosignatures is, however, limited by many factors including lack of preservation of certain species or whole communities of microorganisms, severe degradation of the organic molecules making up the microorganisms, lack of resolution in certain analytical techniques (specifically, isotopic), contamination of the ancient rocks by younger microorganisms, and abiogenic precipitations mimicking simple microbial morphologies. Despite these limitations, the early record of life documents an Earth that appears to have been widely colonised by prokaryote-like microorganisms that lived and interacted with their immediate microcosms in exactly the same way as modern prokaryotes. Organisms obtaining their energy from reduction-oxidation processes of inorganic and organic substances colonised the surfaces of the volcanic rocks and sand grains (the early Earth was characterised by volcanic rocks and detritus) and probably inhabited hydrothermal environments. The widespread development of microbial mats in shallow water littoral environments suggests that life had also learnt how to obtain energy using sunlight (photosynthesis). This ability was of fundamental importance in the further evolution of life since the energy produced by this process is far greater than that produced by chemotrophic metabolisms. All these processes occurred on an Earth that had very little free oxygen. It is widely believed that one of the major causes of the appearance of oxygen in the atmosphere was the ability of certain organisms to split the water molecule and to liberate oxygen during a more advanced version of photosynthesis (oxygenic). This type of metabolism was even more energetically-productive. Evidence from molecular fossils suggests that this metabolism was established by 2.7 Ga, whereas certain microbial structures, such as large stromatolites existing in older rocks 2.8 Ga indicate that oxygenic synthesisers had already taken hold on the Earth. Further complexification of life required significant resources in energy and, thus, the availability of oxygen. BIOGRAPHIES OF PARTICIPANTS John Baross. Professor, School of Oceanography and Center for Astrobiology and Early Evolution, University of Washington, Seattle, WA. John Baross received a BS degree in microbiology and chemistry from San Francisco State University and a PhD degree in marine microbiology from the University of Washington. His research specialty is the ecology, physiology and molecular phylogeny of microorganisms from hydrothermal vent and subseafloor environments... Steven A. Benner received his B.S. and M.S. in Molecular Biophysics and Biochemistry from Yale University, and his Ph.D. in Chemistry from Harvard University. Following two years as a Junior Fellow at the Harvard Society of Fellows, he served on the faculty of Harvard University, the Swiss Federal Institute of Technology, and the University of Florida. He is presently a Distinguished Fellow at the Foundation for Applied Molecular Evolution and The Westheimer Institute for Science and Technology, which he founded... Willy Benz was born on 6 July 1955 in Neuchatel. He studied physics at the University of Neuchatel and received his PhD in natural sciences at the University of Geneva in 1984 for his doctoral thesis in astrophysics. He then went on to do post-doctoral work at Los Alamos National Laboratory (USA) and at Harvard University. In 1987 he was appointed assistant professor at Harvard University. He later taught at the University of Arizona and at the University of Geneva. Willy Benz has been a professor at the Physics Institute at the University of Bern since 1997, becoming institute director in 2002... Michel Blanc dedicated the early years of his scientific career to the Earth magnetosphere and ionosphere, first with models of electric field systems, then with global models of the magnetospheric convection and of radiation belts. Since the early 1990’s, he has obtained important new results on planetary magnetospheres, in particular on plasma transport and radiation belts in the highly axisymetric environment of Saturn. He has played a lead role in the Cassini/Huygens mission as an Interdisciplinary Scientist in Magnetospheres and Plasma Science. He is lead European scientist on a mission (Europa Jupiter System Mission) to orbit Jupiter’s moons Europa and Ganymede... Julie C. Castillo-Rogez is a planetary scientist in the Planetary Ices group at the Jet Propulsion Laboratory, California Institute of Technology. She received her PhD in geophysics from Rennes University, France. She came to JPL in 2002 to participate in the planning and implementation of observations by the Cassini-Huygens mission at Saturn’s satellites. Since then, she has been involved in the science definition of several prospective missions to the outer Solar system... David Charbonneau is the Thomas D. Cabot Associate Professor of Astronomy at Harvard University. His research focuses on the development of novel techniques for the detection and characterization of planets orbiting nearby stars. As a graduate student, he used a 10cm telescope to make the first detection of an exoplanet eclipsing its parent star, which yielded the first ever constraint on the composition of a planet outside the Solar system... Shelley D. Copley obtained an A.B. in Biochemical Sciences (1980) and a Ph.D. in Biophysics (1987) from Harvard University. After post-doctoral work at MIT and the University of Colorado at Boulder, she joined the Department of Chemistry and Biochemistry at the University of Colorado at Boulder in 1990. She moved to the Department of Molecular, Cellular and Developmental Biology in 2000... Athena Coustenis is Director of Research at the Centre National de la Recherche Scientifique (CNRS) of France. As an astrophysicist she works in the field of Planetology at the Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (LESIA) of Paris-Meudon Observatory, France. Her research is devoted to the investigation of planetary atmospheres and surfaces, with emphasis on Titan, Saturn’s largest satellite... Paul Davies is a British-born theoretical physicist, cosmologist, astrobiologist and best-selling author. He held academic appointments at the Universities of Cambridge, London and Newcastle upon Tyne, until 1990, when he moved to Australia, as Professor of Mathematical Physics at The University of Adelaide, and later as Professor of Natural Philosophy at Macquarie University in Sydney, where he helped establish the NASA-affiliated Australian Centre for Astrobiology. He joined Arizona State University in 2006 as Director of Beyond, a research center devoted to exploring the ‘big questions’ of science... Eric J. Gaidos is an Associate Professor of Geobiology in the Department of Geology and Geophysics at the University of Hawaii at Manoa. He is also a graduate faculty in the Department of Oceanography, a research affiliate of the Institute for Astronomy, and a faculty member in the undergraduate Global Environmental Science program... Chris Impey is a University Distinguished Professor and Deputy Head of the Department, in charge of all academic programs. His research interests are observational cosmology, gravitational lensing, and the evolution and structure of galaxies. He has 160 refereed publications and 60 conference proceedings, and his work has been supported by $18 million in grants from NASA and the NSF... James F. Kasting Ph.D., FAAAS is Professor of Geosciences, Pennsylvania State University. He is on the Editorial Boards of Astrobiology and Geobiology. He is a member of the NASA Advisory Council Astrophysics Subcommittee. His research interests are atmospheric evolution, planetary atmospheres, and paleoclimates... Joseph L. Kirschvink is the Van Wingen Professor of Geobiology at the California Institute of Technology, where he heads a research group dedicated to the study of weakly magnetized biological and geological materials. Besides conducting basic science in rock and paleomagnetism, Joe has originated several hypotheses aimed at increasing our understanding of how biological evolution has influenced, and has been influenced by, major events on the surface of the Earth... Andrew H. Knoll is the Fisher Professor of Natural History at Harvard University. He received his B.A. in Geology from Lehigh University in 1973 and his Ph.D., also in Geology, from Harvard in 1977. Following five years on the faculty of Oberlin College, Knoll returned to Harvard as Associate Professor of Biology. He has been a member of the Harvard faculty ever since, serving as Professor of Biology and Professor of Earth and Planetary Sciences... Cardinal Giovanni Lajolo, President of the Pontifical Commission for Vatican City State and President of the Governorate of Vatican City State, was born on 3 January 1935 in Novara, Italy. He was ordained a priest on 29 April 1960 and holds licentiates in theology and philosophy from the Pontifical Gregorian University, and a doctorate in canon law from the Kanonistisches Institut of the Ludwig Maximilian University in Munich, Germany... Christophe Lovis. I am a postdoctoral researcher in the extra solar planet group at the Department of Astronomy of the University of Geneva, Switzerland. I obtained my Ph.D. in Astronomy and Astrophysics at the same institution in 2007. My work has been mainly focused on the search for low-mass extrasolar planets using in particular the HARPS instrument... Jonathan I. Lunine is Professor of Planetary Sciences and Physics and a Galileo Circle Faculty Fellow at the University of Arizona, Tucson. He is the David Baltimore Distinguished Visiting Scientist at NASA’s Jet Propulsion Laboratory. His research interests center broadly on the formation and evolution of planets and planetary systems, the nature of organics in the outer solar system, and the processes that lead to the formation of habitable worlds... Dante Minniti is Full Professor at the Department of Astronomy and Astrophysics of the Pontificia Universidad Catolica in Chile, and Adjunct Scholar at the Vatican Observatory. He did the undergraduate studies in Astronomy at the Universidad de Cordoba (Argentina), and obtained the PhD in 1993 at the University of Arizona (USA)... Raymond T. Pierrehumbert, who obtained his PhD from MIT in 1980, is currently the Louis Block Professor in Geophysical Sciences and the College at the University of Chicago. He studies the physics of climate, especially regarding the long-term evolution of the climates of Earth and Mars... Sean N. Raymond received his PhD in Astrophysics from the University of Washington (Seattle, USA) in 2005. He then spent four years as a researcher and NASA Postdoctoral Program fellow at the University of Colorado. Starting in November 2009, he is a full-time researcher for the CNRS at the Observatoire de Bordeaux in France... Dimitar D. Sasselov is a Professor in the Astronomy Department, Harvard University, a founding Director of the Harvard Origins of Life Initiative, and a Senior Advisor in the sciences, Radcliffe Institute for Advanced Study, Harvard University... Sara Seager is the Ellen Swallow Richards Associate Professor of Planetary Science and Associate Professor of Physics at MIT. Before joining MIT in 2007, she spent four years on the senior research staff at the Carnegie Institution of Washington preceded by three years at the Institute for Advanced Study in Princeton, NJ... Franck Selsis works at the Laboratoire d’Astrophysique de Bordeaux, a department of both the University of Bordeaux and CNRS. His research is dedicated to the origin, evolution of planetary atmospheres, in particular the atmosphere of extrasolar planets and the Earth... Roger E. Summons is Professor of Geobiology in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology. Prior to taking up that appointment in 2001 he was at the Australian Geological Survey Organisation, formerly known as the Bureau of Mineral Resources, Geology and Geophysics in Canberra... Jill C. Tarter holds the Bernard M. Oliver Chair for SETI (Search for Extraterrestrial Intelligence) and is Director of the Center for SETI Research at the SETI Institute in Mountain View, California... Giovanna Tinetti is a lecturer at the University College London and a Royal Society University Research Fellow. She coordinates there a team on extrasolar planets since 2007. G. Tinetti obtained a MSc and a PhD in theoretical physics from the University of Torino, Italy, but her scientific interests slowly shifted to Astrobiology and Extrasolar Planets during her PhD thesis with Prof. Luigi Sertorio... Frances Westall is Director of Research at Centre de Biophysique Moléculaire, Orléans, France (CNRS). Her research interests are the geological context of the origin of life, scenarios for the origin of life, earliest evidence for life on Earth and the importation of prebiotic molecules to the Earth, as well as the search for life on Mars. She is the ExoMars Microscope co-Team Coordinator... For the biographies of the other Academicians of the PAS, cf. Pontificia Academia Scientiarvm, Yearbook (Vatican City 2008), p. 15 ff. LIST OF PARTICIPANTS Prof. John Baross University of Washington, School of Oceanography and Center for Astrobiology and Early Evolution, Seattle, WA (USA) Dr. Steven A. Benner The Westheimer Institute for Science and Technology, Foundation for Applied Molecular Evolution, Gainesville, FL (USA) Prof. Dr. Willy Benz University of Bern, Physics Institute, Bern (Switzerland) Prof. Michel Blanc École Polytechnique, Palaiseau (France) Prof. Nicola Cabibbo, President The Pontifical Academy of Sciences (Vatican City) Dr. Julie C. Castillo Rogez California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA (USA) Prof. David Charbonneau Harvard University, Department of Astronomy, Cambridge, MA (USA) Prof. Shelley D. Copley University of Colorado at Boulder, Department of Chemistry and Biochemistry (CIRES), Boulder, CO (USA) Dr. Athena Coustenis Observatoire de Paris-Meudon, LESIA/CNRS, Meudon (France) Prof. Paul Davies Arizona State University, College of Liberal Arts and Sciences, Tempe, AZ (USA) Rev. Prof. José G. Funes, S.J., Director Specola Vaticana (Vatican City) Prof. Eric J. Gaidos University of Hawai’i at Manoa, School of Ocean and Earth Science and Technology, Dept. of Geology and Geophysics, Honolulu, HI (USA) Prof. Chris Impey The University of Arizona, Department of Astronomy and The Steward Observatory, Tucson, AZ (USA) Prof. James F. Kasting The Pennsylvania State University, Department of Geosciences, University Park, PA (USA) Prof. Joseph L. Kirschvink California Institute of Technology, Division of Geological & Planetary Sciences, Pasadena, CA (USA) Prof. Andrew H. Knoll Harvard University, Department of Earth and Planetary Sciences, Cambridge, MA (USA) H.Em. Card. Giovanni Lajolo President of the Pontifical Commission for Vatican City State and President of the Governorate of Vatican City State (Vatican City) Prof. Christophe Lovis Université de Genève, Observatoire Astronomique, Sauverny (Switzerland) Prof. Jonathan I. Lunine University of Roma, Tor Vergata, Department of Physics, Rome (Italy) Prof. Dante Minniti Pontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Santiago (Chile) Prof. Raymond T. Pierrehumbert University of Chicago, Department of Geophysical Sciences, Chicago, IL (USA) Prof. Sean N. Raymond University of Colorado, Boulder, Center for Astrophysics and Space Astronomy, Boulder, CO (USA) H.E. Msgr. Prof. Marcelo Sánchez Sorondo, Chancellor The Pontifical Academy of Sciences (Vatican City) Prof. Dimitar D. Sasselov Harvard University, FAS Department of Astronomy, Cambridge, MA (USA) Prof. Sara Seager Massachusetts Institute of Technology, Cambridge, MA (USA) Prof. Franck Selsis Université de Bordeaux, Laboratoire d’Astrophysique (LAB), Bordeaux (France) Prof. Roger E. Summons Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Sciences, Cambridge, MA (USA) Prof. Jill C. Tarter SETI Institute, Mountain View, CA (USA) Dr. Giovanna Tinetti University College London, Department of Physics and Astronomy, The Centre For Planetary Sciences, London (UK) Prof. Rafael Vicuña Pontificia Universidad Católica de Chile, Facultad de Ciencias Biológicas, Santiago (Chile) Dr. Frances Westall CNRS, Centre de Biophysique Moléculaire, Orléans (France) Memorandum 1) Every day a bus will leave the Domus Sanctae Marthae at 8:45 for the Academy, fifteen minutes before the beginning of the session. A bus will depart from the Academy after dinner at the end of the afternoon sessions to take participants back to the Domus Sanctae Marthae. Lunch and dinner for the participants will be served at the Academy every day except on Sunday, 8 November, when only dinner will be served after the pilgrimage to the Basilica of St Francis in Assisi. 2) On Sunday, for those wishing to attend, there will be a day-trip to the Basilica of St Francis in Assisi, where Mass will be held at 12:00, followed by lunch at the Franciscan Abbey. If you would like to attend, please inform the Secretariat as soon as possible, and a bus will pick you up at 7:00 from the Domus Sanctae Marthae. Note Please give your form for the refunding of expenses to the Secretariat at least one day before your departure so that you can be refunded immediately. 5 November 2009 • (17) FRONT COVER: The globe of Mars, hand-painted around 1916 by Ingeborg Bruhn, is based on the maps of Percival Lowell (Vatican Observatory). MAP LABELS: - Sede della Pontificia Accademia delle Scienze / Seat of the Pontifical Academy of Sciences (CASINA PIO IV) - Chiesa di Santo Stefano degli Abissini / St Stephen of the Abyssinians Church - Ingresso del Perugino / The ‘Perugino’ gate - Domus Sanctae Marthae - Altare Tomba S. Pietro / Altar of St Peter’s Tomb - Ingresso Sant’Uffizio / The ‘Sant’Uffizio’ gate - Ingresso Sant’Anna / The ‘Sant’Anna’ gate - Ingresso Musei Vaticani / Entrance gate to the Vatican Museum THE PONTIFICAL ACADEMY OF SCIENCES CASINA PIO IV • V-00120 VATICAN CITY Tel: +39 0669883451 • Fax: +39 0669885218 Email: [email protected] For further information please visit: http://www.vatican.va/roman_curia/pontifical_academies/acdscien/index.htm