Rev166: May 11th - May 28th 2012, Tethys, Methone, Titan |
Rev166: May 11th - May 28th 2012, Tethys, Methone, Titan |
May 11 2012, 11:48 AM
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#1
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
Latest looking ahead article is available.
I've been looking forward to this one for a while as we get our first decent look at Methone Closest ISS activity is from 4,500km, which should yield images comparable to the best views we have so far of Atlas. There are also images planned of Tethys' trailing hemisphere from mid-ranges, and of course a close (955km) Titan flyby with specular-reflection searches, and radar swaths at C/A. This is the flyby whereby Titan bends Cassini's orbit 'down' and out of the ring plane for the next couple of years. I know we can't have it all, but I was hoping for another decent look at Telesto on this rev (Cassini buzzes past at around 11,000km) which would have given us images at high phases and from almost the same range as the flyby in 2005. Never mind, there's another similar-range pass to Telesto in 2015. Lots to look forward to. Jase |
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May 25 2012, 05:46 PM
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#2
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Member Group: Members Posts: 219 Joined: 14-November 11 From: Washington, DC Member No.: 6237 |
What is the orientation of Methone? Is the long axis pointed towards Saturn (similar to a gravity-gradient stabilized spacecraft)? If this is in fact a loose dust pile, is this the expected type of deformation?
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May 25 2012, 09:26 PM
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#3
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
What is the orientation of Methone? Is the long axis pointed towards Saturn (similar to a gravity-gradient stabilized spacecraft)? If this is in fact a loose dust pile, is this the expected type of deformation? I like replying to a first post because it gives me the chance to say: Helllo and welcome. I don't know the answer to your question, but it's a good question! My first guess is that material is deposited preferentially around the equator as is the case with Atlas so no reorientation is needed for that, in fact it's self-stabilising. That establishes an oblate ellipsoid with one short axis and two long ones. I'm not sure that the recent images imply a significant difference between the two axes in the equatorial plane, so it may not have 'a' long axis. |
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May 26 2012, 04:04 AM
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#4
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Member Group: Members Posts: 219 Joined: 14-November 11 From: Washington, DC Member No.: 6237 |
I like replying to a first post because it gives me the chance to say: Helllo and welcome. I don't know the answer to your question, but it's a good question! My first guess is that material is deposited preferentially around the equator as is the case with Atlas so no reorientation is needed for that, in fact it's self-stabilising. That establishes an oblate ellipsoid with one short axis and two long ones. I'm not sure that the recent images imply a significant difference between the two axes in the equatorial plane, so it may not have 'a' long axis. Heh... I've been lurking a while, didn't realize it was actually my first. Thanks for the welcome. I've learned a lot here! So Methone is shaped more like a Skittle than a football? That wasn't clear (to my uncalibrated eye) from the images, or comparisons others made to elongated asteroids, and I hadn't seen any actual 3-axis numbers, just a mean radius estimate. But it guess it would be a more expected shape for something that formed there versus being captured. I guess we'll see. |
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May 26 2012, 01:10 PM
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#5
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Member Group: Members Posts: 613 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
So Methone is shaped more like a Skittle than a football? Hmm. I suggest with an international audience skittle and football are poor words to use as shape descriptors..... Skittle, upper case, as in the (US) candy means oblate spheroid (one short radius, two long) and could be referred to by the UK sweet named a Smartie (like US M&M ; I'm a big fan of food analogies in planetary science, by the way...) but a skittle (lower case, UK useage) could refer to a bowling pin - a perhaps bi-lobed prolate spheroid (two short radii, one long) rather like comet Borelly. So without catching the case of the leading character, it's a bit ambiguous. And then there is football, which to much of the world means a sphere (or a convex-hulled truncated icosahedron leather approximation of the same) rather than the prolate ellipsoid which you actually mean in US useage..... ;-) Maybe someone can make a cool montage of confectionery and sports goods, with the aspect ratios and end radii marked up - maybe there are even some 'universal' confections like (originally Italian) Tic-Tac's that are good analogs of planetary bodies... |
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