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The search for organics on Mars with the Mars Science Laboratory “Curiosity”: the next mission to Mars

The search for organics on Mars with the Mars Science Laboratory “Curiosity”: the next mission to Mars. 12 April 2012 Chris McKay NASA Ames Research Center chris.mckay@nasa.gov. Viking on Mars: Life & organics . Viking. The three Biology Experiments sought to detect life.

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The search for organics on Mars with the Mars Science Laboratory “Curiosity”: the next mission to Mars

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  1. The search for organics on Mars with the Mars Science Laboratory “Curiosity”: the next mission to Mars 12 April 2012 Chris McKay NASA Ames Research Center chris.mckay@nasa.gov

  2. Viking on Mars: Life & organics

  3. Viking • The three Biology Experiments sought to detect life. • The GCMS sought to detect and characterize organic molecules.

  4. The Viking Biology Experiments

  5. CH3Cl "The methyl chloride, or part of it, could conceivably be indigenous to Mars. However, if it were, one would expect that other related compounds like ethyl chloride or methyl bromide would also be formed, but none were detected." Viking 1 results Biemann et al. 1977 Biemann et al. 1977 detected a sharp methyl chloride peak at VL1.

  6. Biemann et al. 1997 reported detection of 8 “contaminants” at VL2 but one of them (methlyene chloride) was not detected in flight blanks and is the expected result of perchlorate and organics heated to high temperature.

  7. There should be organics on Mars • From meteorites • From any early biology

  8. Phoenix Mission to Mars May 2008 to Nov 2008

  9. Unexpected Phoenix results Soil pH ~8 Carbonates 3-5% Perchlorate 0.5% Segregated ice  No organics No nitrates } Instrument failures

  10. bleach salt

  11. The Cl atom is present on Mars: it molecular form is unknown except at the Phoenix site, where it is predominately perchlorate Keller et al. JGR 2006

  12. Perchlorates on Mars • Perhclorates decomposeand release oxygen whenheated to ~350ºC- used in rockets- destroys organics- produces organo-chlorides • Strong anti-freeze (-70ºC)- allow liquid on Mars today • Consumed by microorganisms- terminal electron acceptor ≈ nitrate • Bad for humans (drinking water limit in California is 6 ppb; Mars is 5,000,000 ppb)

  13. Mars-like Soils: The Atacama Desert in Chile is an organic and microbiological analog of Mars: Atacama Desert Mars • Very low content of organics on surface • Low recoverable DNA and no CFU • Presence of abiotic oxidants Navarro-Gonzalez et al. Science 2003

  14.  Atacama soil Atacama soil with 1% perchlorate added Adding perchlorate: • Organics gone • NO gone • CH3CL and CH2Cl2 Navarro-Gonzalez, R., E. Vargas, J. de la Rosa, A. C. Raga, and C. P. McKay (2010),Reanalysis of the Viking results suggests perchlorate and organics at mid-latitudes on Mars,J. Geophys. Res., doi:10.1029/2010JE003599.

  15. Organics on Mars • Everything we thought we knew about organics on Mars from the Viking pyrolysis GCMS is likely wrong • Instead of an upper limit of ~ ppb, detection (by destruction) at ~ ppm • Good news for future missions: organics might be high. • Bad news for future missions: need non-thermal methods

  16. The next mission to Mars: Mars Science Laboratory Launched: Nov. 2011 Landing: 5 Aug 2012 10:15 pm PDT

  17. Gale Crater 20 km landing ellipse

  18. There is a pyrolysis GCMS on the upcoming MSL mission Sample Analysis for Mars Combustion with O2 to CO2 Liquid extraction, SAM will wash the samples with two derivatization agents: tetramethylammonium hydroxide &N-Methyl-N-(Tert-Butyldimethylsilyl) trifluoroacetamide Head space monitoring during pyrolysis

  19. Two sources of non-biological organic materials: Meteorites and Miller-Urey synthesis experiments How do they differ from life? Two sources of non-biological organic materials: Two sources of non-biological organic materials: Life Miller-Urey Experiments

  20. The building blocks of Earth life. Could be different for alien life forms. Lehninger, Biochemistry, 1975 page 21

  21. Concentration Abiotic organic Chemistry Type of molecule

  22. Concentration Abiotic organic Chemistry Type of molecule Concentration Biology Type of molecule

  23. Concentration Abiotic organic Chemistry Type of molecule Concentration Biology Type of molecule Concentration Different Biology Type of molecule

  24. this slide intentionally left banke

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