1. Jet Propulsion Laboratory California Institute of Technology Pasadena California 91109 USA
2. Planetary Geosciences Institute Department of Earth and Planetary Sciences University of Tennessee Knoxville Tennessee 37996 USA
3. Department of Natural Resources Management and Agricultural Engineering Laboratory of Mineralogy and Geology Agricultural University of Athens 11855 Athens Greece
4. Division of Geological and Planetary Sciences California Institute of Technology Pasadena California 91125 USA
5. Department of Geosciences Virginia Tech Blacksburg Virginia 24061 USA