Phobos 1 Phobos 1 Phobos 1 was an unmanned Russian space probe of the Phobos Program launched from the Baikonour launch facility on 7 July 1988. Its intended mission was to explore Mars and its moons Phobos and Deimos. The mission failed on 2 September 1988 when a computer malfunction caused the end-of-mission order to be transmitted to the spacecraft. At the time of launch it was the heaviest interplanetary spacecraft ever launched, weighing . It was to take an estimated 200 days for the "Phobos 1" space probe to travel from the Earth to Mars. Two mid-course corrections were planned. The
Planet that objects that fulfill the orbital zone clearance requirement automatically fulfill the roundness requirement. The table below lists Solar System bodies once considered to be planets. Beyond the scientific community, Pluto still holds cultural significance for many in the general public due to its historical classification as a planet from 1930 to 2006. A few astronomers, such as Alan Stern, consider dwarf planets and the larger moons to be planets, based on a purely geophysical definition of "planet". The names for the planets in the Western world are derived from the naming practices of the Romans, which ultimately derive from