 DEIMOS

Deimos's orbit is nearly circular and is close to Mars's equatorial plane.Deimos is possibly an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still controversial and disputed.Both Deimos and Phobos have very circular orbits which lie almost exactly in Mars' equatorial plane, and hence a capture origin requires a mechanism for circularizing the initially highly eccentric orbit, and adjusting its inclination into the equatorial plane, most likely by a combination of atmospheric drag and tidal forces; it is not clear that sufficient time was available for this to have occurred for Deimos.