Origin of Phobos and Deimos, Where did these guys come from? Options

[djellison]

I would think gravitational disturbances with such low masses would be very minor at that distance...

Extrapolate a tiny tiny force, over millions and millions of years.

What do you get? A big difference.

You even need to include things like solar pressure etc etc. Very long period orbital extrapolation is fraught with nature's subtle influence, much of which is very hard to simulate.

[Phil Stooke]

The real problem here is that these kinds of orbital extrapolations only work for limited periods. The system becomes chaotic especially near any resonances, and as Doug pointed out there could have been other short-lived chunks which would make it even more chaotic. Even now we can't predict precisely where the two moons will be from one decade to the next - the MSL Mastcam images on about sol 42 showed the moons a bit off where they were expected (there's an LPSC abstract on it somewhere). So we can't possibly extrapolate backwards very far.

Phil

[Chmee]

In the debate over the origin of Phobos and Deimos, it looks like several recent papers have been published supporting the 'giant impactor' theory. Here are the abstracts to a couple very interesting papers on this subject:

"Are Phobos and Deimos the result of a giant impact?" - Robert A. Craddock Icarus Volume 211, Issue 2, February 2011, Pages 1150–1161

"On the formation of the martian moons from a circum-martian accretion disk" Pascal Rosenblatt Icarus Volume 221, Issue 2, November–December 2012, Pages 806–815