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W. K. Hartmann (Planetary Science Institute)
New data from Mars Global Surveyor and Mars Odyssey, along with new data from Martian meteoritic rocks and global climate models, indicate a planet with more water resources and more recent geologic activity than was thought only a decade ago. Geomorphic indicators reveal massive subsurface ice at depths of a few hundred meters; Mars Odyssey confirmed roughly 50% ice in the top few meters of soil at 65 degrees latitude. Mars rocks show exposure to water in the recent past, including one event dated at 670 MY ago. Mars rocks and crater counts indicate lava eruptions and even some limited river channel cutting activity in the last few hundred MY. Dynamical studies indicate axial tilt changes up to 50 degrees on a 15 MY roughly-cyclic timescale. Global climate models under different obliquities indicate patch ice deposition over a wide range of latitudes during the different obliquity states. These may explain young hillside gullies and possible young glacial features.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.