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
Formation and evolution of the Solar System possibility is where the primary and moon are tidally locked to each other. In that case, the tidal bulge stays directly under the moon, there is no transfer of angular momentum, and the orbital period will not change. Pluto and Charon are an example of this type of configuration. Prior to the 2004 arrival of the "Cassini–Huygens" spacecraft, the rings of Saturn were widely thought to be much younger than the Solar System and were not expected to survive beyond another 300 million years. Gravitational interactions with Saturn's moons were expected to gradually sweep the rings' outer edge toward the