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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Mar 29 2009, 07:30 PM
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Member Group: Members Posts: 696 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
A harder question for the capture hypothesis, I think, is why the inclination of the orbits is so low (1.1 and 1.8 degrees for Phobos and Deimos respectively). It's harder to damp inclination than it is to damp eccentricity (Triton, for example, has an inclination of 157 degrees and an eccentricity of zero). Unfortunately this paper doesn't mention inclination damping at all.
John. |
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