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
Mars One all the research, supplier Lockheed Martin says that the technologies were viable. Another serious concern uncovered in the research conducted by MIT is replacement parts. The PhD candidates estimated the need for spare parts in a Mars colony based on the failure rates of parts on the ISS. They determined that a resupply mission every two years would be necessary unless a large space in the initial launch were to be reserved for extra materials. Lansdorp commented on this saying, "They are correct. The major challenge of Mars One is keeping everything up and running. We don't believe what we