June 12 2007 Icy Moons (rev 46) |
June 12 2007 Icy Moons (rev 46) |
Jun 6 2007, 07:35 AM
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Senior Member Group: Members Posts: 1887 Joined: 20-November 04 From: Iowa Member No.: 110 |
Rev 46 description available at CICLOPS
http://ciclops.org/view.php?id=3245 Some highlights: Cassini will observe Mimas, the innermost of the mid-sized icy satellites of Saturn June 12, Cassini makes one of its closest passes of the small, inner satellite Atlas, at a distance of only 38,000 km (24,000 mi). With an average diameter of only 31 km (19 mi), Atlas is one of the smallest moons of Saturn. Atlas will only appear to be 120 pixels across (at the equator). However, these images may still provide important clues about the formation of one of the most distinguishing aspects of the tiny satellite: its equatorial bulge. The bulge is thought to have been created by material from Saturn’s A ring being deposited preferentially along the equator of the satellite. A number of observations are dedicated to observing some of Saturn's small moons, in order to refine scientists' estimates of their orbital paths. These sequences include observations of some of Saturn's outer satellites, such as Paaliaq, Hati, and S/2004 S13 I've seen a few of these small outer moons listed recently on the raw image page. They search tool only shows them from the last few orbits. Is this something new they are doing or have they been previously listed as Sky? |
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Jun 24 2007, 11:58 PM
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
David, I think you are combining things which have been said about other small bodies here - a rapidly spinning elongated object, rotating about its short axis, may have the ends of its elongated shape gravitationally lower despite their larger radii. Peter Thomas of Cornell did pioneering work on this phenomenon, which he called dynamic topography, especially with reference to Phobos, Deimos, Gaspra and Ida, in the 90s.
Until new we have not known the shape of Atlas well enough to think about it in this context. My impression is of a "flying saucer" shape with a central bulge - the wrinkly bit we see here - and a big equatorial ridge which now looks as if it extends all around the equator, though a bit irregular. That ridge may be made of ring particles deposited on the satellite, maybe during special events in the history of the system such as an interaction with a ringlet. At this distance from Saturn the dynamic topography would be dominated by Saturn's gravitational gradient across Atlas plus its rather rapid rotation. I'm sure we will see more on this when a full shape model can be constructed. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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