Asteroid Capture Theory

Mars's moons, Phobos and Deimos, share many characteristics with two types of asteroids common in the belt: C- and D-type asteroids.

Moreover, by the looks of Phobos and Deimos, we can easily assume that they are both captured objects from the Asteroid Belt, that maybe there was a collision that sent them off into the direction where Mars's gravitational pull would confine them.

Many questions still lie with whether they are captured asteroid and their circular orbits over the history of the solar system.