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
Exploration of Mars one of the proponents of such missions. Various asteroids, moons, and places on Mars can be mined while crops are initially being planted. This method will save lives on Earth, add potentially trillions of dollars to the world economy annually, and provide a stable colony on Mars. Some have also stated that persons should stay on Earth, but get food and resources from Mars and surrounding asteroids, moons, greenhouses in space and other structures. Some critics contend unmanned robots can perform better than humans at a fraction of the expense. If life exists on Mars, a human mission could contaminate