Capture of Phobos and Deimos, Paper AAAS - 57725 by Geoffrey Landis |
Capture of Phobos and Deimos, Paper AAAS - 57725 by Geoffrey Landis |
Mar 29 2009, 01:23 AM
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Member Group: Members Posts: 236 Joined: 5-June 08 From: Udon Thani Member No.: 4185 |
see http://arxiv.org/abs/0903.3434 QUOTE The origin of the Martian moons Deimos and Phobos is controversial. One hypothesis for their origin is that they are captured asteroids, but the mechanism requires an extremely dense martian atmosphere, and the mechanism by which an asteroid in solar orbit could shed sufficient orbital energy to be captured into Mars orbit has not been well elucidated. Since the discovery by the space probe Galileo that the asteroid Ida has a moon "Dactyl", a significant number of asteroids have been discovered to have smaller asteroids in orbit about them. The existence of asteroid moons provides a mechanism for the capture of the Martian moons (and the small moons of the outer planets). When a binary asteroid makes a close approach to a planet, tidal forces can strip the moon from the asteroid. Depending on the phasing, the asteroid can then be captured. Clearly, the same process can be used to explain the origin of any of the small moons in the solar system. Interesting theory. |
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May 23 2009, 09:18 AM
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Junior Member Group: Members Posts: 47 Joined: 27-December 07 Member No.: 3991 |
Hmm, can I go silly, why not, It was said that early in our systems history, the Earth was maybe hit by a large object and the debris formed the Moon. Perhaps Deimos and Phobos are hunks of Mars itself blasted into orbit by such collision in the early system of rogue objects that were eventually ejected or destroyed and partially absorbed. Maybe Mars could be surrounded by hunks of Earth, blasted into space by the collision that created the Moon. The grooves on Phobos could be, rock layers from a larger original planetary sized body. It's not hard to imagine a few fish, whales, trees and other unexpected things to be in space. Earth has been hit very hard a few times since life has been on it, to blast such material into space. There are bits of everything everywhere. I like to collect meteorites, can you tell?
Isn't it weird how so many objects have these one face toward the planet orbits. Why do some moons rotate in relation to their parent body and others not, is this a clue to their formation? There is probably some lumps of stuff ejected from other star systems floating around in ours somewhere, hope a little bits lands, or someone finds a bit that already has. :-) |
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May 23 2009, 05:19 PM
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Senior Member Group: Members Posts: 1018 Joined: 29-November 05 From: Seattle, WA, USA Member No.: 590 |
Hmm, can I go silly, why not, . . . Because this is a serious site, not a silly one. Lots of real scientists read and post here, and they're generally happy to answer serious questions. Isn't it weird how so many objects have these one face toward the planet orbits. Why do some moons rotate in relation to their parent body and others not, is this a clue to their formation? I'd say this qualifies as a serious question. :-) Tidal forces cause this behavior in small bodies which orbit close to large ones. If you found a close-in moon that did rotate with respect to its planet, then you'd be entitled to speculate that it had been captured very recently. Exceptions (like Mercury and Hyperion) are very educational in their own right. --Greg |
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