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 Cube One Mars Cube One Mars Cube One (or MarCO) is a Mars flyby mission that was launched on 5 May 2018 alongside NASA's "InSight" Mars lander mission. It consists of two nanospacecraft, MarCO-A and MarCO-B, that were able to provide a real-time communications link to Earth for "InSight" during its entry, descent, and landing (EDL) on 26 November 2018 - when "InSight" was out of line of sight from the Earth. Both are of the 6U CubeSat format, and the mission is a test of new miniaturized communications and navigation technologies. These are the first CubeSats designed to operate beyond Earth