Computer simulations suggest that Mars' puzzling moons, Phobos and Deimos, may have been formed from debris created when a large asteroid wandered dangerously close to the Red Planet.
This new model proposes that Phobos and Deimos resulted from the wreckage of a larger asteroid that wandered too close to Mars and crossed its Roche limit — the distance at which gravitational tidal forces emanating from the planet became too great and tore the asteroid apart.
