1. Center for Earth and Planetary Studies, Smithsonian Institution, Washington, DC 20560, USA.
2. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85251, USA.
3. Carl Sagan Center, SETI Institute, Mountain View, CA 94043, USA.
4. NASA Ames Research Center, Moffett Field, CA 94035–0001, USA.
5. Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.
6. Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA.
7. Institut für Planetologie, Westfälische Wilhelms-Universität, 48149 Münster, Germany.
8. Department of Geological Sciences, Brown University, Box 1846, Providence, RI 02912, USA.
9. Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA.
10. Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.