Mars' two moons, Phobos and Deimos, are not so good. They are quite small and abundantly unremarkable. In fact, Mars' bigger moon, Phobos, is slowly crumbling apart due to stress, which is perhaps its only relatable quality. So how did Mars -- a nice, round planet -- give rise to such garbage moons? The answer may lie in its turbulent youth, when it was possibly pelted with a large asteroid.