Titan's topography, strange.... |
Titan's topography, strange.... |
Apr 12 2009, 12:44 PM
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#1
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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 21 2009, 03:36 PM
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#2
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
I've just peformed an experiment which crudely simulates what I think happens to the sandflow at Xanadu. It only took a few minutes to set up. No pics unfortunately but here's what I did.
I set up an airtrack at a slight gradient. Above the airtrack I positioned a hairdryer angled slightly downwards but facing the airtrack's uphill direction. Before starting the airflow to the track I placed three pucks well spaced out along it and turned on the hairdryer. On starting the airflow to the track the pucks began moving downhill, remaining evenly spaced. As the first one approached the hairdryer it stopped and reversed back up until the second puck ran into it. Now joined together (blu-tack) the first two pucks came to a halt in front of the hairdryer. When the third puck caught up with the first two they collectively overcame the headwind from the hairdryer and all moved through together. |
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Apr 22 2009, 07:45 PM
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#3
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Member Group: Members Posts: 131 Joined: 30-August 06 From: Moscow, Idaho Member No.: 1086 |
I've just peformed an experiment which crudely simulates what I think happens to the sandflow at Xanadu. An interesting idea. If this were true, then what we might see would be Barchan dunes racing around Xanadu to the North and South, carrying these spillover sands faster than the longitudinal dunes. I haven't seen this in the VIMS data, but we might reasonably not be expected to given small Barchans and our outrageously crappy spatial resolution near 90W. Does RADAR see anything? My personal best guess right now (subject to change when more data arrive!) is that there is no net sandflow through Xanadu, and that in general W-to-E flux of sand is rather low (but nonzero!). - VIMS Jason |
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Apr 22 2009, 09:37 PM
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#4
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
My personal best guess right now (subject to change when more data arrive!) is that there is no net sandflow through Xanadu, and that in general W-to-E flux of sand is rather low (but nonzero!). The fast-moving mid-latitude barchans is an interesting idea too, but I have a query about your last point. As ever we are bedevilled by our ignorance of timescales for Titan's active processes. Are you saying that unidirectional flow could produce the observed sand sea features yet still be so low that even after hundreds of millions of years (maybe!) the sand would not all have piled up on western Xanadu? For the record what my experiment was attempting to simulate was the periodic overwhelming of Xanadu by a whole sand sea in one big flush, after which (being bright) it would dust itself off quite quickly and remain sand free for perhaps another million years, damming the flow completely as we seem to see it doing now. |
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