1. M. J. S. Belton, National Optical Astronomy Observatories, 950 North Cherry Ave, Tucson, AZ 85719, USA.
2. J. W. Head III, R. Pappalardo, G. Collins, Department of Geological Science, Brown University, Providence, RI 02912, USA.
3. A. P. Ingersoll and A. R. Vasavada, Department of Geology and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
4. R. Greeley and R. Sullivan, Department of Geology, Arizona State University, Tempe, AZ 85287-1414, USA.
5. A. S. McEwen, P. Geissler, R. Greenberg, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 87721, USA.
6. K. P. Klaasen, D. Senske, T. V. Johnson, G. S. Orton, R. A. West, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
7. D. Simonelli, J. Veverka, P. J. Gierasch, D. Banfield, M. Bell, J. A. Burns, P. Thomas, Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.
8. M. H. Carr, U.S. Geological Survey, Menlo Park, CA 94025, USA.
9. M. E. Davies, RAND, Santa Monica, CA 90406, USA.
10. C. R. Chapman, Southwest Research Institute, Boulder, CO 80302, USA.
11. C. Anger, ITTRES Ltd, Calgary, Alberta TIY 5Z6, Canada.
12. G. Neukum, Institute for Planetary Exploration, Deutsche Forschunganstalt für Luft und Raumfahrt, Berlin, Germany.
13. C. B. Pilcher, National Aeronautical and Space Administration, Washington, DC 20546, USA.
14. R. F. Beebe, Department of Astronomy, New Mexico State University, Las Cruces, NM 88003, USA.
15. F. Fanale, Institute for Geophysics, University of Hawaii, Honolulu, HI 96822, USA.
16. W. Ip, Max Planck Institute für Aeronomie, Lindau, Germany. D. Morrison and J. Moore, NASA Ames Research Center, Moffett Field, CA 94035, USA.