The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover’s robotic arm.

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The Sample Analysis at Mars Investigation and Instrument Suite

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane–ethane surface lakes on Saturn’s large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life.

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What makes a planet habitable

■ Abstract Giant planets have now been discovered around other stars, and it is only a matter of time until Earth-sized planets are detected. Whether any of these planets are suitable for life depends on their volatile abundances, especially water, and on their climates. Only planets within the liquid-water habitable zone (HZ) can support life on their surfaces and, thus, can be analyzed remotely to determine whether they are inhabited. Fortunately, current models predict that HZs are relatively wide around main-sequence stars not too different from our sun. This conclusion is based on studies of how our own planet has evolved over time. Earth’s climate has remained conducive to life for the past 3.5 billion years or more, despite a large increase in solar luminosity, probably because of previous higher concentrations of CO 2 and/or CH4. Both these gases are involved in negative feedback loops that help to stabilize the climate. In addition to these topics, we also briefly discuss the rise of atmospheric O 2 and O3, along with their possible significance as indicators of life on other planets.

Evolution of a Habitable Planet

We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders of magnitude than previously thought. The balance between slow hydrogen escape and volcanic outgassing could have maintained a hydrogen mixing ratio of more than 30%. The production of prebiotic organic compounds in such an atmosphere would have been more efficient than either exogenous delivery or synthesis in hydrothermal systems. The organic soup in the oceans and ponds on early Earth would have been a more favorable place for the origin of life than previously thought.

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A hydrogen-rich early Earth atmosphere

Acknowledgements Foreword Introduction I BACKGROUND Long-term astrophysical processes Evolution theory and the future of humanity Millenial tendencies in responses to apocalyptic threats Cognitive biases potentially affecting judgement of global risks Observation selection effects and global catastrophic risks Systems-based risk analysis Catastrophes and insurance Public policy towards catastrophe II RISKS FROM NATURE Super-volcanism and other geophysical processes of catastrophic import Hazards from comets and asteroids Influence of Supernovae, gamma-ray bursts, solar flares, and cosmic rays on the terrestrial environment III RISKS FROM UNINTENDED CONSEQUENCES Climate change and global risk Plagues and pandemics: past, present, and future Artificial Intelligence as a positive and negative factor in global risk Big troubles, imagined and real IV RISKS FROM HOSTILE ACTS Catastrophe, social collapse, and and human extinction The continuing threat of nuclear war Catastrophic nuclear terrorism: a preventable peril Biotechnology and biosecurity Nanotechnology as global catastrophic risk The totalitarian threat Author's biographies Index

Global Catastrophic Risks

Stellar nucleosynthesis of heavy elements such as carbon allowed the formation of organic molecules in space, which appear to be widespread in our Galaxy. The physical and chemical conditions—including density, temperature, ultraviolet (UV) radiation and energetic particles—determine reaction pathways and the complexity of organic molecules in different space environments. Dense interstellar clouds are the birth sites of stars of all masses and their planetary systems. During the protostellar collapse, interstellar organic molecules in gaseous and solid phases are integrated into protostellar disks from which planets and smaller solar

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Astrophysical and astrochemical insights into the origin of life

Preface. 1 The Synthesis of the Elements and the Formation of Stars M. Spaans. 2 Organic Molecules in the Interstellar Medium T.J. Millar. 3 Chemistry of Protoplanetary Disks Relation to Primitive Solar System Material A.J. Markwick and S.B. Charnley. 4 Planet Formation: Problems and Prospects G. Wuchterl. 5 From Elemental Carbon to Complex Macromolecular Networks in Space F. Cataldo. 6 Organic Molecules in Planetary Atmospheres M. Roos-Serote. 7 Observations and Laboratory Data of Planetary Organics T.L. Rousch and D.P. Cruikshank. 8 The Molecular Complexity of Comets J. Crovisier. 9 Kuiper belt: Water and Organics C. de Bergh. 10 Interplanetary Dust Particles and Astrobiology F.J. Molster. 11 The Prebiotic Atmosphere of the Earth F. Selsis. 12 Early Life on Earth: The Ancient Fossil Record F. Westall. 13 Highly Altered Organic Matter on Earth: Biosignature Relevance B.A. Hofmann. 14 Insoluble Organic Matter in Carbonaceous Chondrites and Archean Cherts. An Insight into their Structure by Electron Paramagnetic Resonance L. Binet, D. Gourier, A. Skrzypczak, S. Derenne, and F. Robert. 15 The Chemistry of the Origin of Life O. Botta. 16 A Novel Synthesis of Biomolecular Precursors R. Saladino, C. Creestini, F. Ciciriello, G. Costanzo, R. Negri, and E. Di Mauro.

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Astrobiology: Future Perspectives

The subject of Astrobiology can be approached from many different perspectives, as reflected in numerous textbooks, journals, conference proceedings, web documentation and popular literature. This book is focused on abiotic organic matter from the viewpoint of astronomy and planetary science and considers its potential relevance to the origins of life on Earth and elsewhere. Guided by the review papers in this book, this concluding chapter aims to identify key questions to motivate future research and stimulate astrobiological applications of current and future research facilities and space missions.

Anne Dutrey

Papers

Astrophysical and astrochemical insights into the origin of life

Astrophysical and astrochemical insights into the origin of life

Astrobiology: Future Perspectives

Future Perspectives and Strategies in Astrobiology