US Space Stations                        
       The first American space station was Skylab, weighing 75 tones and measuring 25 m (82 ft) long, made from the converted top stage of a Saturn 5 rocket. The Skylab program is more complex and extensive than the Salyut programs.
      In 1973 and 1974 the Skylab space station supported three crews of three astronauts each for periods of up to 84 days. Skylab was as large as a small two-bedroom house, contained extensive sanitary facilities, and usually maintained a constant temperature. Skylab astronauts were able to perform many scientific experiments in this environment. Many experiments on the effects of weightlessness were conducted, and astronauts studied the Earth and Sun with the telescope and infrared spectrometer. Solar panels provided the electricity needed to run the station. More than
740 hours were spent in observing the Sun with telescopes, and 175,000 solar pictures were returned to Earth, as were about 64 km (40 mi) of electronic data tape and 46,000 photographs of the Earth's surface. On July 11, 1979, during orbit number 34,981, Skylab plunged to Earth, raining fiery debris over sparsely populated Western Australia and over the Indian Ocean.