HR: 15:00h
AN: P43A-05    [Abstracts]
TI: Water ice Crystallinity and Grain Sizes on Dione
AU: * Newman, S F
EM: Sarah.F.Newman@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr M/S 183-501, Pasadena, CA 91109, United States
AU: Buratti, B B
EM: bburatti@scn.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr M/S 183-501, Pasadena, CA 91109, United States
AU: Brown, R H
EM: rhb@lpl.arizona.edu
AF: Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd. P.O. Box 210092, Tucson, AZ 85721-0092, United States
AU: Jaumann, R
EM: ralf.jaumann@dlr.de
AF: German Aerospace Center (DLR), Rutherfordstraße 2, Berlin, 12489, Germany
AU: Bauer, J M
EM: James.M.Bauer@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr M/S 183-501, Pasadena, CA 91109, United States
AU: Momary, T W
EM: momary@mail.jpl.nasa.gov
AF: Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr M/S 183-501, Pasadena, CA 91109, United States
AB: Using data from the Cassini Visual and Infrared Mapping Spectrometer (VIMS), we examine the properties of the dark and wispy terrains found on Dione, and provide interpretations to their varying content. Mapping of a "crystallinity factor" on the surface of Dione, using the shape of the 3.1 micron Fresnel reflection peak, indicates that the dark areas are more amorphous than the surrounding terrain and the interweaving wispy streaks. Alternatively, these effects could be produced by grain size variations, if the dark terrain consists of sub-micron sized particles. We also report preliminary analysis of grain sizes on Dione, suggesting that the wispy streaks and the bright background regions contain ice particles of similar size and the dark terrain contains smaller particles. We discuss implications for these results, including an exogenous source for the dark material and possible geologic activity on Dione, which could produce fissures supplying fresh crystalline ice, as in the case of Enceladus.
DE: 6020 Ices
DE: 6055 Surfaces
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly