Dawn Mission to Vesta and Ceres Symbiosis between Terrestrial Observations and Robotic Exploration

The initial exploration of any planetary object requires a careful mission design guided by our knowledge of that object as gained by terrestrial observers. This process is very evident in the development of the Dawn mission to the minor planets 1 Ceres and 4 Vesta. This mission was designed to verify the basaltic nature of Vesta inferred both from its reflectance spectrum and from the composition of the howardite, eucrite and diogenite meteorites believed to have originated on Vesta. Hubble Space Telescope observations have determined Vesta’s size and shape, which, together with masses inferred from gravitational perturbations, have provided estimates of its density. These investigations have enabled the Dawn team to choose the appropriate instrumentation and to design its orbital operations at Vesta. Until recently Ceres has remained more of an enigma. Adaptive-optics and HST observations now have provided data from which we can begin C. T. Russell (&) IGPP & ESS, UCLA, Los Angeles, CA 90095-1567, USA e-mail: [email protected] F. Capaccioni INAF, Via del fosso del Cavaliere, Rome 00133, Italy A. Coradini IFSI, Via del fosso del Cavaliere, Rome 00133, Italy M. C. De Sanctis IAFS, Via del fosso del Cavaliere, Rome 00133, Italy W. C. Feldman T. H. Prettyman LANL, MS D466, NIS-1, Los Alamos, NM 87545, USA R. Jaumann S. Mottola DLR Rutherfordstr 2, 12489 Berlin, Germany H. U. Keller MPAE, 37191 Katlenburg-Lindau, Germany T. B. McCord University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822, USA 123 Earth Moon Planet (2007) 101:65–91 DOI 10.1007/s11038-007-9151-9