PAPPALARDO Robert¹、GOLDSTEIN Barry¹、MAGNER Thomas²、PROCKTER Louise²、SENSKE David¹、PACZKOWSKI Brian¹、COOKE Brian¹、*Vance Steven¹、PATTERSON G. Wesley² (1.Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109、2.The Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, 20723)