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Astronauts and Robots 2015: David Des Marais, NASA


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American Astronautical Society, Astronauts and Robots: Partners in Space Exploration, May 12-13, 2015 -

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Astronauts and Robots 2015: David Des Marais, NASA

  2. 2. AstrobiologyAstrobiology Concepts of LifeConcepts of Life in the Contexts of Marsin the Contexts of Mars informationinformation storage andstorage and replicationreplication energyenergy harvesting andharvesting and transductiontransduction organicorganic biosynthesisbiosynthesis EVOLUTIONEVOLUTION
  3. 3. solutes demand supply extremes impose costs solubility Adapted from T. Hoehler
  4. 4. Depth(mbsf) 12108642 Log (cells·mL-1 ) ● Eq. Pacific ● N.Pac.Gyre ● S.Pac.Gyre ● ODP ● Non-ODP Biomass Density: Pacific Ocean Sediments (Kallmeyer et al., AGU 2009) 107.5 x Productivity modulated by energy availability …
  5. 5. (Des Marais et al., 2008)
  6. 6. Propagation is possible Mars’ surface environment today (NASA/JPL Special Regions Science Advisory Group, 2006)
  7. 7. Open Basin Lakes N=>210 (~65% newly recognized) Fassett and Head, 2008a,b Noachian Valley Networks and Open Basin LakesAncient Martian Stream Systems and Lakes Early climates were wetter and perhaps also somewhat warmer
  8. 8. NN BonnevilleBonneville CraterCrater ColumbiaColumbia HillsHills RegionRegion BasalticBasaltic PlainsPlains ColumbiaColumbia MemorialMemorial StationStation (Lander)(Lander) HomeHome PlatePlate WestWest SpurSpur HusbandHusband HillHill Spirit’s Traverse in Gusev Crater
  9. 9. Rocks and soils (regolith fines) within reach Which ones to focus on? Targeted Remote Sensing observations Which ones to touch? Contact observations Which ones to sample? samples Deciphering Geological Processes and History Quantity of Geologic Observations After E2E-iSAG QUANTITY OF GEOLOGIC OBSERVATIONS “Well documented” means that the appropriate geologic measurements have been carried out across the exploration area to provide maximum constraints on the interpretation of the sample analysis. To ensure that a site, or samples from it, are “well documented” requires using the rover’s tools and instruments to make a sufficient quantity, variety and quality of geologic observations to interpret past environmental conditions and understand spatial and temporal relationships in the geologic record.
  10. 10. 06/03/15 132020 Mars Rover Science Definition Team Scientific Process for Detecting Past Martian Life POTENTIAL FOR BIOSIGNATURE PRESERVATIO N EXISTENCE OF POTENTIAL BIOSIGNATURE PRE-CONDITIONS THAT MUST HAVE BEEN MET Past conditions suitable for the existence of life at the site. Past conditions suitable for the preservation of past life in the geologic record. An observable feature that might be evidence of past life. RECOGNITION OF DEFINITIVE BIOSIGNATURE An observable feature that is confirmed to be evidence of past life. POSSIBLE EVIDENCE OF ANY PAST LIFE PAST LIFE DETECTED Proposed Mars 2020 Rover Labs on Earth MSR PAST HABITABLE ENVIRONMENT To search for potential biosignatures, it is necessary to (a) identify sites that very likely hosted past habitable environments, (b) identify high biosignature preservation potential materials to be analyzed for potential biosignatures, and (c) perform measurements to identify potential biosignatures or materials that might contain them.
  11. 11. Summary • Mars system science: address interactions between geological, climate (and life?) processes over spatial and temporal scales • “Habitability” spans orders of magnitude; this range matters in our search for life • Integrate observations across broad spatial and temporal scales: site selection, landed remote sensing, contact science, sample selection, in- depth sample analysis • An optimal human-robot synergy addresses challenges at all scales of observation adapted from A. Pohorille
  13. 13. Biosignatures: What We Look For… Body Fossils Biominerals Biofabrics Chemical Fossils (Biomarkers) Stable Isotopes Des Marais (2014) Gases Metabolism
  14. 14. End
  15. 15. Evolution (descent with modification) Life’s Basic Functions Des Marais (2014)
  16. 16. Solvent for life • Life requires self-organization of organic matter mediated by non-covalent interactions… • Interactions must be well balanced; this implies a high dielectric constant and a robust solvophobic effect • The solvent should support life over sufficiently wide ranges of T & P (& pH?) • The solvent must be chemically active adapted from A. Pohorille
  17. 17. Mineralogical Traces of Early Habitable EnvironmentsWater (availability, activity, composition), Energy (level, flux), Temp., pH, Salinity Energy balance analysis Energy Demand = f (T, pH, fluid comp., self-repair) Energy Supply = f (T, pH, fluid comp., & host matrix) (these factors combine to determine how habitable a system may be) Extremes in T, pH, salinity, radiation, etc. impose substantial energy demands (T. Hoehler, 2011)
  18. 18. presence of reduced carbon (e.g., graphite, diamonds) • Distributions of identifiable molecular structures and/or components (if macromolecular) Low High presence of organic carbon (compounds with C-H bonds) • Isomer ratios of amino acids OM Detection ConfidenceScale • molecular mass distribution of organic components • compound specific isotopic composition • aliphatic/aromatic ratio • organic functionalization (polar/nonpolar) • C, H, O, S, N, Cl ratios of organic matter • fine scale OM distribution in materials Basic molecular bond information OrganicMatterCharacterization Different types of organic matter measurements provide different levels of confidence in a biological origin for the organic matter (OM)* Stable isotopic composition of organic carbon * The level of confidence provided by a given measurement varies depending on the specific details (e.g. degree of thermal degradation) of the sample being investigated 06/03/15 232020 Mars Rover Science Definition Team
  19. 19. Des Marais (2001)