Phobos program Phobos program The Phobos (, ) program was an unmanned space mission consisting of two probes launched by the Soviet Union to study Mars and its moons Phobos and Deimos. "Phobos 1" was launched on 7 July 1988, and "Phobos 2" on 12 July 1988, each aboard a Proton-K rocket. "Phobos 1" suffered a terminal failure en route to Mars. "Phobos 2" attained Mars orbit, but contact was lost before the final phase, prior to deployment of a planned Phobos lander. "Phobos 1" and "2" were of a new spacecraft design, succeeding the type used in the "Venera" planetary missions
Small Solar System body natural satellites (moons) differ from small Solar System bodies not in size, but in their orbits. The orbits of natural satellites are not centered on the Sun, but around other Solar System objects such as planets, dwarf planets, and small Solar System bodies. Some of the larger small Solar System bodies may be reclassified in future as dwarf planets, pending further examination to determine whether or not they are in hydrostatic equilibrium. The orbits of the vast majority of small Solar System bodies are located in two distinct areas, namely the asteroid belt and the Kuiper belt. These two belts