History: NASA Archive Photography

Skylab was the United States' first and only independently built space station. The 169,950 lb (77,088 kg) orbital workshop was launched on May 14, 1973, into a 235-nautical-mile (435 km) orbit inclined at 50° to the equator. Damaged during launch by the loss of its thermal protection and one electricity-generating solar panel, it was repaired to functionality by its first crew. It was occupied for a total of 171 days by 3 successive crews in 1973 and 1974. It included a laboratory for studying the effects of microgravity, and a solar observatory. NASA planned to have a Space Shuttle dock with it, and elevate Skylab to a higher safe altitude, but the Shuttle was not ready for flight before Skylab's re-entry on July 11, 1979.
Apollo spacecraft were used for bringing astronauts to and from the Skylab. Three three-man crews stayed aboard the station for periods of 28, 59, and 84 days. Skylab's habitable volume was 319.8 cubic meters (11,290 cu ft), which was 30.7 times bigger than that of the Apollo Command Module.
- Apollo-Soyuz Test Project (1975–1981)
In the 1970s the cold war was thawing and as a consequence the Apollo-Soyuz Test Project (ASTP) was introduced. It was the first joint flight of the U.S. and Soviet space programs. The mission took place in July 1975. For the United States, it was the last Apollo flight, as well as the last manned space launch until the flight of the first Space Shuttle in April 1981. Manned Skylab and ASTP missions used the smaller Saturn IB with Apollo CSM, not the Saturn V.