Paul K. Byrne, Lillian R. Ostrach, Brett W. Denevi, Clark R. Chapman, Caleb I. Fassett, Jennifer L. Whitten, Christian Klimczak, Erwan Mazarico, Steven A. Hauck, II, James W. Head, and Sean C. Solomon. 1Lunar and Planetary Institute, Universities Space Research Association, Houston, TX 77058 (byrne@lpi.usra.edu); Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015; Solar System Exploration Division, NASA Goddard Space Flight Center, MD 20771; The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723; Department of Space Studies, Southwest Research Institute, Boulder, CO 80302; Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075; Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912; Department of Geology, University of Georgia, Athens, GA 30602; Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, OH 44106; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964.