Moons of Mars formed a large moon. Gravitational interactions between this moon and the outer ring formed Phobos and Deimos. Later, the large moon crashed into Mars, but the two small moons remained in orbit. This theory agrees with the fine-grained surface of the moons and their high porosity. The outer disk would create fine-grained material. While many Martian probes provided images and other data about Phobos and Deimos, only few were dedicated to these satellites and intended to perform a flyby or landing on the surface. Two probes under the Soviet Phobos program were successfully launched in 1988, but neither conducted the
Colonization of the outer Solar System Colonization of the outer Solar System Many parts of the outer Solar System have been considered for possible future colonization. Most of the larger moons of the outer planets contain water ice, liquid water, and organic compounds that might be useful for sustaining human life. Colonies in the outer Solar System could also serve as centers for long-term investigation of the planet and the other moons. In particular, robotic devices could be controlled by humans without the very long time delays incurred in communicating with Earth. There have also been proposals to place robotic aerostats in the upper atmospheres of