1. School of Physics and Astronomy, University of Minnesota, Minneapolis 55455
2. Center for Space Sciences, University of Texas, Dallas 75080
3. Ames Research Center, Moffett Field, California 94035
4. Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts 02138
5. Goddard Space Flight Center, Greenbelt, Maryland 20771
6. Viking Project Office, NASA Langley Research Center, Hampton, Virginia 23365
7. Martin Marietta Corporation, P. O. Box 179, Denver, Colorado 80201