CASSINI ISS OBSERVATIONS OF SATURN'S ICY SATELLITES DIONE, TETHYS, RHEA, MIMAS, HYPERION AND PHOEBE

Starting with a 2000 km altitude flyby of Saturn's small outermost satellite, Phoebe, in June 2004, Cassini has been returning a wealth of new information about the saturnian satellites. In its first year in Saturn orbit the spacecraft has had encounters within at least 150,000 km of each of the intermediate and large icy satellites and several others at significantly lower altitudes. To date, images acquired by Cassini's Imaging Science Subsystem (ISS) have provided many insights into the nature of the satellites' surfaces and the processes, primarily tectonic and impact cratering, acting upon them. Observations of small, heavily cratered Phoebe support the hypothesis that it is a captured object that originated in the outer Solar System. The bright wispy terrain Voyager observed on Dione has been revealed to consist of multiple sets of fractures with bright scarps. Diverse impact crater morphologies have also been observed. We will present, and discuss interpretations of, these ISS observations as well as those planned in upcoming opportunities. Cassini is due to pass within just 170 km of the surface of Enceladus on 14 July 2005 and flybys within 500-1500 km of Tethys, Hyperion, and Dione are currently planned for fall 2005. A number of distant encounters with other satellites are also planned during the summer and fall of 2005.