Catherine M. Corrigan

Combining meteorites and missions to explore Mars

Laboratory studies of meteorites and robotic exploration of Mars reveal scant atmosphere, no evidence of plate tectonics, past evidence for abundant water, and a protracted igneous evolution. Despite indirect hints, direct evidence of a martian origin came with the discovery of trapped atmospheric gases in one meteorite. Since then, the study of martian meteorites and findings from missions have been linked. Although the meteorite source locations are unknown, impact ejection modeling and spectral mapping of Mars suggest derivation from small craters in terrains of Amazonian to Hesperian age. Whereas most martian meteorites are young (< 1.3 Ga), the spread of whole rock isotopic compositions results from crystallization of a magma ocean > 4.5 Ga and formation of enriched and depleted reservoirs. However, the history inferred from martian meteorites conflicts with results from recent Mars missions, calling into doubt whether the igneous histor y inferred from the meteorites is applicable to Mars as a whole. Allan Hills 84001 dates to 4.09 Ga and contains fluid-deposited carbonates. Accompanying debate about the mechanism and temperature of origin of the carbonates came several features suggestive of past microbial life in the carbonates. Although highly disputed, the suggestion spurred interest in habitable extreme environments on Earth and throughout the Solar System. A flotilla of subsequent spacecraft has redefined Mars from a volcanic planet to a hydrologically active planet that may have harbored life. Understanding the history and habitability of Mars depends on understanding the coupling of the atmosphere, surface, and subsurface. Sample return that brings back direct evidence from these diverse reservoirs is essential.

35 Seasons of U.S. Antarctic Meteorites (1976-2010): A Pictorial Guide to the Collection

Preface v Contributors vii 1 The Origin and Early History of the U.S. Antarctic Search for Meteorites Program (ANSMET) 1 Ursula B. Marvin 2 Fieldwork Methods of the U.S. Antarctic Search for Meteorites Program 23 Ralph P. Harvey, John Schutt, and Jim Karner 3 Curation and Allocation of Samples in the U.S. Antarctic Meteorite Collection 43 Kevin Righter, Cecilia E. Satterwhite, Kathleen M. McBride, Catherine M. Corrigan, and Linda C. Welzenbach Pictorial Guide to Selected Meteorites 4 Primitive Asteroids: Expanding the Range of Known Primitive Materials 65 Michael K. Weisberg and Kevin Righter 5 Achondrites and Irons: Products of Magmatism on Strongly Heated Asteroids 79 David W. Mittlefehldt and Timothy J. McCoy 6 ANSMET Meteorites from the Moon 101 Randy L. Korotev and Ryan A. Zeigler 7 Meteorites from Mars, via Antarctica 131 Harry Y. McSween, Jr., Ralph P. Harvey, and Catherine M. Corrigan 8 Meteorite Misfits: Fuzzy Clues to Solar System Processes 145 Timothy J. McCoy 9 Cosmogenic Nuclides in Antarctic Meteorites 153 Gregory F. Herzog, Marc W. Caffee, and A. J. Timothy Jull 10 A Statistical Look at the U.S. Antarctic Meteorite Collection 173 Catherine M. Corrigan, Linda C. Welzenbach, Kevin Righter, Kathleen M. McBride, Timothy J. McCoy, Ralph P. Harvey, and Cecilia E. Satterwhite Index 189