1. Department of Geological Sciences, University of Alaska Anchorage, Anchorage, Alaska 99508, USA
2. Departments of Astronomy & Earth and Atmospheric Sciences, Cornell University, Ithaca, New York 14853, USA
3. Department of Geology, University of Maryland, College Park, Maryland 20742, USA
4. Planetary Science Institute, Tucson, Arizona 85719, USA
5. Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas 77058, USA
6. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
7. Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, USA