1. Division of Geological & Planetary Sciences California Institute of Technology Pasadena CA USA
2. Now at Johns Hopkins University/Applied Physics Laboratory Laurel MD USA
3. Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA
4. Institut de Recherche en Astrophysique et Planétologie (IRAP) Université de Toulouse CNRS UPS CNES Toulouse France
5. Geosciences Environnement Toulouse (GET) Université de Toulouse CNRS UPS Toulouse France
6. Department of Earth & Environmental Sciences Columbia University Lamont Doherty Earth Observatory Palisades NY USA