1. D. S. McKay, Mail Code SN, NASA Lyndon B. Johnson Space Center (JSC), Houston, TX 77058, USA.
2. E. K. Gibson Jr., Mail Code SN4, NASA-JSC, Houston, TX 77058, USA.
3. K. L. Thomas-Keprta, Lockheed Martin, Mail Code C23, 2400 NASA Road 1, Houston, TX 77058, USA.
4. H. Vali, Department of Earth and Planetary Sciences, McGill University, 3450 University St., Montreal, Quebec, H3A 2A7 Canada.
5. C. S. Romanek, Savannah River Ecology Laboratory, Drawer E, University of Georgia, Aiken, SC 29802, USA.
6. S. J. Clemett, X. D. F. Chillier, C. R. Maechling, R. N. Zare, Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.