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Shoreline Features of Titan’s Ontario Lacus from Cassini/VIMS Observations
Icarus (2009)
  • Jason W. Barnes, NASA Ames Research Center
  • Robert H. Brown, University of Arizona
  • Jason M. Soderblom, University of Arizona
  • Laurence A. Soderblom
  • Ralf Jaumann
  • Brian Jackson, University of Arizona
  • Université de Nantes, Université de Nantes
  • Christophe Sotin, California Institute of Technology
  • Bonnie J. Buratti, California Institute of Technology
  • Karly M. Pitman, California Institute of Technology
  • Kevin H. Baines, California Institute of Technology
  • Roger N. Clark
  • Phillip D. Nicholson, Cornell University
  • Elizabeth P. Turtle, Johns Hopkins University
  • Jason Perry, University of Arizona
We analyze observations of Titan's south polar lake Ontario Lacus obtained by Cassini's Visual and Infrared Mapping Spectrometer during the 38th flyby of Titan (T38; 2007 December 5). These near-closest-approach observations have the highest signal-to-noise, the finest spatial resolution, and the least atmospheric influence of any near-infrared lake observation to date. We use the large, spatially flat, and low-albedo interior of Ontario Lacus as a calibration target allowing us to derive an analytical atmospheric correction for emission angle. The dark lake interior is surrounded by two separate annuli that follow the lake interior's contours. The inner annulus is uniformly dark, but not so much as the interior lake, and is generally 5–10 kilometers wide at the lake's southeastern margin. We propose that it represents wet lakebed sediments exposed by either tidal sloshing of the lake or seasonal methane loss leading to lower lake-volume. The exterior annulus is bright and shows a spectrum consistent with a relatively low water-ice content relative to the rest of Titan. It may represent fine-grained condensate deposits from a past era of higher lake level. Together, the annuli seem to indicate that the lake level for Ontario Lacus has changed over time. This hypothesis can be tested with observations scheduled for future Titan flybys.
  • Titan
Publication Date
May, 2009
Publisher Statement

This is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online at Icarus, published by Elsevier. Copyright restrictions may apply. doi: 10.1016/j.icarus.2008.12.028

Citation Information
Jason W. Barnes, Robert H. Brown, Jason M. Soderblom, Laurence A. Soderblom, et al.. "Shoreline Features of Titan’s Ontario Lacus from Cassini/VIMS Observations" Icarus Vol. 201 Iss. 1 (2009)
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