SPACE STATION

manned artificial satellite designed to revolve in a fixed orbit and to serve as a base for scientific observation and experiment, for refueling spacecraft, or for launching satellites and missiles. The Soviet Union made the first attempt to establish a space station with the launch of Salyut 1 on April 19, 1971. The 8,619-kilogram (19,000-pound) craft was 7.6 m (25 feet) long. This first attempt was unsuccessful; the Salyut was designed to stay in permanent orbit, but its low orbit caused it to reenter the Earth's atmosphere within six months. The United States orbited the first successful experimental space station on May 14, 1973. This station, called Skylab, was manned by three separate flight crews for a total of 171 days between May 25, 1973, and Feb. 8, 1974. The astronauts conducted varied scientific studies on board the orbiting space laboratory, including observations of the Sun and the Comet Kohoutek and the manufacture of superconductors from molten mixtures of gold and germanium. The 75-ton station reentered the Earth's atmosphere in July 1979 and disintegrated. From 1974 to 1982 the Soviets succeeded in orbiting a series of smaller space stationsSalyuts 3 through 7. Salyut 6 was occupied for a total of 676 days, and it reentered Earth atmosphere in 1982, three months after the launching of Salyut 7. Like their American counterparts, Soviet cosmonauts performed biomedical and other scientific work aboard the station for extended periods of time, the longest being a record-setting 237 days in 1984. On Feb. 20, 1986, the Soviets launched a new space station designed to serve as the core of a permanent manned orbiting facility. Known as Mir, the station had six docking ports for cargo transports, visiting manned spacecraft, and expansion modules, designed to be used as research laboratories and living quarters.