1. Jet Propulsion Laboratory; California Institute of Technology; Pasadena California 91109 USA
2. School of Earth and Space Exploration; Arizona State University; Tempe Arizona 85281 USA
3. NASA Postdoctoral Management Program Fellow; NASA Headquarters; Washington District of Columbia 20546 USA
4. Department of Earth and Planetary Sciences; The University of Tennessee in Knoxville; Knoxville Tennessee 37996 USA
5. Department of Earth and Planetary Sciences; Harvard University; Cambridge Massachusetts 02138 USA
6. IRAP; Université de Toulouse; CNRS; UPS; 31003 Toulouse France
7. Planetary Science Institute; Tucson Arizona 85719 USA