Titan's topography, strange.... |
Titan's topography, strange.... |
Apr 12 2009, 12:44 PM
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Recent article in Science by Zebker et al.:
Zebker et al. Science in press, "Size and Shape of Saturn's Moon Titan". doi: 10.1126/science.1168905 (published online April 2, 2009) Link to abstract (pay-for article): http://www.sciencemag.org/cgi/content/abstract/1168905 Article on spaceref discusses this paper: http://www.spaceref.com/news/viewpr.html?pid=27912 Figure 3 from the Science article is a global elevation map relative to barycenter. Key points of article:
"Xanadu seems to be systematically lower than other parts of the equatorial belt, and not uplifted like most mountainous areas on Earth." (quote from Fig. 3 caption in article) -Mike -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Apr 12 2009, 04:00 PM
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
So now a Big Question:
Why are the poles wet, the equatorial Sand Seas dry, and Xanadu dry and sand-free? The elevation difference can explain why the poles are wet: QUOTE (from Zebker et al. Science in press, "Size and Shape of Saturn's Moon Titan". doi: 10.1126/science.1168905 (published online April 2, 2009): If we posit that the lakes are surface expressions of a more or less continuous liquid organic "water table," then the lower elevations of the poles could lead to the observed preponderance of lakes at high latitudes. However, whether the polar surface intersects a methane table depends on its distance from a constant gravity potential surface, and not the on its elevation from the barycenter, because the equipotential may be depressed as well at the poles. But keeping lower lying downwind Xanadu free from Shangri-La's dune sands is harder to explain. If the equipotential is depressed at Xanadu (due to a lower overall density of crustal materials), this could explain why the mobile dune sands remain in Shangri-La (which is higher barycentric elevation) and don't fill in Xanadu. Otherwise some funky physical barriers would need to be invoked. [The sand seas could be isolated from the north polar lakes due to many reasons: an isolating temperate airfall deposit, lack of sand reservoirs, lack of winds carrying material into the poles, and also sands getting trapped by the lakes] This Science paper is awesome. It raises a lot of really tough questions..... -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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