HR: 1340h
AN: P13C-1427    [Abstracts]
TI: Iapetus: Ultraviolet Measurements from Cassini
AU: * Hendrix, A R
EM: hendrix@jpl.nasa.gov
AF: JPL/Caltech, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
AU: Hansen, C J
EM: candice.j.hansen@jpl.nasa.gov
AF: JPL/Caltech, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
AB: The Cassini spacecraft will make an unprecedented flyby of Iapetus, the enigmatic moon of Saturn, on September 10, 2007. The flyby, at an altitude of ~1645 km, will provide spectacular opportunities for observations of the bright-dark boundary on the anti-Saturnian hemisphere, as well as the first high-resolution views of the higher-albedo trailing hemisphere. The Ultraviolet Imaging Spectrograph (UVIS) will participate in the remote sensing campaign to study the surface composition of Iapetus, and will also perform a stellar occultation to search for any atmospheric gases. The previous Iapetus flyby (December 2004), at ~123,000 km, focused on the low-albedo leading hemisphere and yielded intriguing results about the dark terrain; UVIS spectra showed that the water ice absorption band is present even in the darkest, lowest latitudes of the central leading hemisphere. This result suggests the possibility of an ongoing coating process by an exogenic source of the dark material. Water ice has a distinctive absorption feature at ~165 nm and is readily observed by UVIS, allowing for compositional and grain size mapping.
DE: 6020 Ices
DE: 6055 Surfaces
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting