36th DPS Meeting, 8-12 November 2004
Session 27 Mars Surface and Water I: MER
Special Session, Thursday, November 11, 2004, 10:30am-12:00noon, Lewis

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[27.02] Water and the Many Faces of Salt at the MER Sites

B. C. Clark (Lockheed Martin), Athena Science Team

Detections of salt-forming elements at previous landing sites have been extended in multiple examples for soils, outcrops, and light and dark rocks at the Meridiani Planum and Gusev Crater rover sites. A general theme of widespread S and Cl and now even Br occurrences is emerging for the planet. Mars Exploration Rover (MER) surface explorations and Mars Express orbital measurements are discovering exposures of very high sulfate concentrations in certain locations. Implicated cations for sulfates include Mg, Ca and Fe. Odyssey observations from orbit show planet-wide abundances of Cl, albeit with intriguing variations. These abundances and their patterns reinforce the evidence for mobilization of soluble salts under aqueous influence, but likewise place significant constraints on the volumes and nature of the interactions of various hydrologic forms of liquid water in the history of the observable martian surface. Physicochemical conditions of diverse weathering regimes may have affected the formation and most certainly the redistribution and diagenetic modification of salt deposits on Mars. Supplementing the abundant geomorphologic evidence for episodic activity by H2O, salt concentrations provide direct evidence for standing bodies of liquid H2O. Future detailed characterization of such salt deposits could establish temperature and saline concentration parameters at times of deposition or alteration, and hence clarify the climate regimes for corresponding times in martian history. Funding support for MER science and mission operations is provided by NASA/JPL.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.