Dawn Mission to Vesta and Ceres
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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 to confidently plan the mission. These observations reveal a rotationally symmetric body with little surface relief, an ultraviolet bright point that can be used as a control point for determining the pole and anchoring a geographic coordinate system. They also reveal albedo and color variations that provide tantalizing hints of surface processes.
KeywordsDawn Discovery mission Asteroids Ceres Vesta
A mission such as Dawn is the culmination of the work of many individuals and many organizations. We are extremely grateful to NASA for continuing to fund Dawn despite continued budgetary stress within the Discovery program. We also thank the German Space Agency, DLR, and the Italian Space Agency, ASI, for living by their commitments to fund their Dawn instruments at times of great stress within their own space programs. In the case of the German Framing Camera an additional strong commitment by the Max Planck Society was essential for the implementation of this investigation. Dawn has also benefited from strong support from its major partners in the US, Orbital Sciences Corporation, and the Jet Propulsion Laboratory. Some of the heroes of the Dawn program include Tom Fraschetti, John McCarthy, Valerie Thomas, Ann Grandfield, Marc Rayman, Joe Makowski, Ed Miller and Mike Violet among many, many others. The funding for the Dawn project in the US comes from the National Aeronautics and Space Administration and is administered by the Jet Propulsion Laboratory.
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