Astronomy Picture of the Day northwest space front .
We do have an ongoing mission to Ceres the dwarf planet..The top level question that the mission addresses is the role of size and water in determining the evolution of the planets. Ceres and Vesta are the right two bodies with which to address this question, as they are the most massive of the protoplanets, baby planets whose growth was interrupted by the formation of Jupiter. Ceres is very primitive and wet while Vesta is evolved and dry. The instrumentation to be flown is complete, flight- proven and similar to that used for Mercury, Mars, the Moon, Eros and comets. The science team consists of leading experts in the investigation of the rocky and icy planets using proven measurement and analysis techniques.
Dawn Mission: Mission > Mission Objectives
ION propulsion on the dawn spacecraft: http://dawn.jpl.nasa.gov/multimedia/ionprop.asp