The Saturnian satellite Rhea as seen by Cassini VIMS

Katrin Stephan, Ralf Jaumann, Roland Wagner, Roger N. Clark, Dale P. Cruikshank, Bernd Giese, Charles A. Hibbitts, Thomas Roatsch, Klaus Dieter Matz, Robert H. Brown, Gianrico Filacchione, Fabrizio Cappacioni, F. Scholten, Bonnie J. Buratti, Gary B. Hansen, Phil D. Nicholson, Kevin H. Baines, Robert M. Nelson, Dennis L. Matson

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Since the arrival of the Cassini spacecraft at Saturn in June 2004, the Visual and Infrared Mapping Spectrometer has obtained new spectral data of the icy satellites of Saturn in the spectral range from 0.35 to 5.2 μm. Numerous flybys were performed at Saturn's second largest satellite Rhea, providing a nearly complete coverage with pixel-ground resolutions sufficient to analyze variations of spectral properties across Rhea's surface in detail. We present an overview of the VIMS observations obtained so far, as well as the analysis of the spectral properties identified in the VIMS spectra and their variations across its surface compared with spatially highly resolved Cassini ISS images and digital elevation models. Spectral variations measured across Rhea's surface are similar to the variations observed in the VIMS observations of its neighbor Dione, implying similar processes causing or at least inducing their occurrence. Thus, magnetospheric particles and dust impacting onto the trailing hemisphere appear to be responsible for the concentration of dark rocky/organic material and minor amounts of CO 2 in the cratered terrain on the trailing hemisphere. Despite the prominent spectral signatures of Rhea's fresh impact crater Inktomi, radiation effects were identified that also affect the H 2O ice-rich cratered terrain of the leading hemisphere. The concentration of H 2O ice in the vicinity of steep tectonic scarps near 270°W and geologically fresh impact craters implies that Rhea exhibits an icy crust at least in the upper few kilometers. Despite the evidence for past tectonic events, no indications of recent endogenically powered processes could be identified in the Cassini data.

Original languageEnglish (US)
Pages (from-to)142-160
Number of pages19
JournalPlanetary and Space Science
Volume61
Issue number1
DOIs
StatePublished - Feb 1 2012

Keywords

  • Cassini/VIMS
  • Icy satellites
  • Rhea
  • Spectroscopy
  • Surfaces

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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