1. National Optical Astronomy Observatories, Tucson, AZ 85719
2. Department of Astronomy, Cornell University, Ithaca, NY 14853
3. Planetary Science Institute, Tucson, AZ 85719
4. RAND, Santa Monica, CA 90406
5. Department of Geology, Arizona State University, Tempe, AZ 85287
6. Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721
7. Department of Geology, Brown University, Providence, RI 02912
8. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
9. U.S. Geological Survey, Flagstaff, AZ 86001
10. NASA/Ames Research Center, Moffett Field, CA 94035
11. Deutsche Forschungsanstalt für Luft und Raumfahrt, 8031 Oberpfaffenhofen, Federal Republic of Germany
12. Institute of Geophysics, University of Hawaii, Honolulu, HI 96822
13. Institute for Space and Terrestrial Science, Concord, Ontario, Canada L4K 3C8
14. U.S. Geological Survey, Menlo Park, CA 94025
15. NASA Headquarters, Washington, DC 20546