But they are small,irregularly shaped, and it seems likely they were asteroids at one time, captured by Mars' gravity. Both were discovered in 1877. Deimos, about 6 km across, further out from Mars, but still close at 23,460 km. Orbits Mars a little over once a day. All local and interplanetary laws apply.
Owners assume legal responsibility for any future collision of their asteroid and the Planet Earth.
Void where prohibited. I dunno, it's probably something Freudian.