North Polar Basin (Mars) suggest that a body approximately 0.02 Mars masses in size is capable of producing a sizable debris disk in Martian orbit, on the order of 5x10 kg, with a significant fraction of the material remaining close to Mars. This figure lies within the estimated mass range necessary to form the two moons, as other data suggests that only 1% of the mass of an accretion disk successfully forms moons. There are several other large impact basins on Mars that could have ejected enough debris to form the moons. Analysis of Mars Global Surveyor data found mineral deposits similar to terminal
Double planet that this definition of double planet depends on the pair's distance from the Sun. If the Earth–Moon system happened to orbit farther away from the Sun than it does now, then Earth would win the tug of war. For example, at the orbit of Mars, the Moon's tug-of-war value would be 1.05. Also, several tiny moons discovered since Asimov's proposal would qualify as double planets by this argument. Neptune's small outer moons Neso and Psamathe, for example, have tug-of-war values of 0.42 and 0.44, less than that of Earth's Moon. Yet their masses are tiny compared to Neptune's, with an