1. Mars Geochemistry and Future Experiment Needs Mark A. Bullock August 7, 2002

2. NASA’s Mars Exploration Program Science-driven program to understand whether Mars is, was, or can be a habitable world. Science goals: – Determine if life ever arose on Mars – Characterize the climate of Mars – Characterize the geology of Mars – Prepare for human exploration of Mars Orbiters, landers, rovers to be launched every 2 years Currently $350M/yr (FY 2002) and increasing Mark A. Bullock August 7, 2002

3. Why is the Earth Just Right?

4. The Big Mars Geochemistry Questions Where did the carbon dioxide go? What are the absolute ages of the different surface units? What can carbon isotopes tell us about past or present life? What can hydrogen and oxygen isotopes tell us about the history of water? What kind of minerals form the soils and rocks of Mars? What is the origin of the Martian salts? Mark A. Bullock August 7, 2002

5. What Does Geochemistry Tell Us? Isotope systems tell us rock ages Precipitated minerals tell us about water related processes Mineralogy tells us about crystallization conditions Light isotope systems tell us about precipitation and possible biological processes Salts tell tales about past water and climate conditions Mark A. Bullock August 7, 2002

6. Viking Lander Measurements Inorganic elemental analysis (XRF) Organic analysis (GCMS) Life detection (GEX, LR, PR) Mark A. Bullock August 7, 2002

7. Mars Pathfinder Results Elemental analysis of rocks and soils (APXS) Multi-color images (NIR/VIS) Rock and soil texture images Magnetic properties Mark A. Bullock August 7, 2002

8. Orbital Measurements Thermal Emission Spectrometer on MGS Composition of surface minerals and ices 5.8 - 50  m interferometric spectrometer 5.1 - 150  m radiometer 0.3 - 2.9  m VIS/NIR radiometer 3 km spatial resolution No evidence for igneous weathered products Mark A. Bullock August 7, 2002

9. Origin of the Martian Salts Martian fines are 16% salt (VL1, VL2, Pathfinder) S/Cl ~ 5 Hydrothermal alteration of rocks (High T) Deposition by volcanic aerosols and gases Groundwater interactions with igneous rocks (Low T) Contributions from meteoritic infall Mark A. Bullock August 7, 2002

10. Future in situ Measurements Mossbauer spectroscopy (Fe minerals) Raman spectroscopy (organic/inorganic) Age dating (K-Ar, 39 Ar- 40 Ar, Rb-Sr, Sm-Nd, and U-Th-Pb to 10 7 years) Microscopy (mineral identification) X-Ray diffraction (mineral identification) Light isotopes (biosignatures) Drilling essential to 5 m Nuclear power for long life, high power Mark A. Bullock August 7, 2002

11. Carbon Isotope Measurements Mark A. Bullock August 7, 2002

12. Hydrogen Isotope Measurements Mark A. Bullock August 7, 2002

13. Oxygen Isotope Measurements Mark A. Bullock August 7, 2002

14. Future Orbital Measurements Upper atmosphere (hot ions, solar/atmosphere interactions, neutral and ion escape fluxes) Near to mid IR (1 - 25  m) at very high spatial and spectral resolution (hydrothermal products) High spatial resolution imagery for landing site reconnaissance (water related features) Support for Mars Sample Return (communications) Mark A. Bullock August 7, 2002

15. Mars Sample Return Ground truth -- allows samples from known geological context Only currently feasible way to do age dating Highest priority Mars goal Major planetary protection and sample handling issues Many technological hurdles (autonomous roving and collection, launch from surface and rendezvous for return) Nuclear powered Mark A. Bullock August 7, 2002

16. Outstanding Scientific Problems Was Mars warm and wet in the past? What happened to its atmosphere? Did Mars ever have a magnetic field? What is the geologic history of Mars? Is there water ice close to the surface? Was there ever life on Mars? Mark A. Bullock August 7, 2002

17. Future Missions to Mars 2003 Rovers2005 Mars Reconnaissance Orbiter 2007 Scout 2009 Smart Lander Mark A. Bullock August 7, 2002

18. NASA Mars Missions

19. The Future of Geochemical Experiments on Mars Looking for life is the ‘Prime Directive’ Geochemistry informs the history of climate, water, and the interior Geochemical experiments will be the richest source of new advances in instrumentation Most technology development will be tied to Mars Sample Return Autonomous roving, drilling, sample collection and handling will be required Nuclear power will mean thinking outside the box Mark A. Bullock August 7, 2002