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
Flag of Mars "red Mars and two moons in blue field above a diagonal, white below". In Robert A. Heinlein's 1961 science-fiction novel "Stranger in a Strange Land", a flag of Mars is hastily improvised, consisting of "the field in white and the sigil of Mars in red". In The Expanse television series, based on "The Expanse" series of novels by James S. A. Corey, the Martian Congressional Republic is the governing body that rules over the inhabitants of Mars and is one of the two human superpowers in the series. Its flag is reminiscent of Mars and its two moons, Phobos and