Why does mars have moons even when its mass is small?

The Roche limit of the mars is higher than if it was near to the sun.

Explanation:

The Roche limit determines the possibility of the orbit around the planet.The Roche limit is the distance within which a moon could be held together  by the planet's own force of gravity or else the moon will disintegrate due to the sun's tidal forces exceeding the planet's gravitational force.The Roche limit increases with the increase in distance from the sun if planet's mass is kept constant.The gravitational force of the mars above its atmosphere could trap a moon which is within the Roche limit.If the mars was closer to the sun, it would have a smaller Roche radius where the orbit of the moon will not be possible. So, the Mars have moons even when its mass is small.