The Skylab was the United States’ first space station and the only one that NASA launched without the help of others. A space station had been planned long before the actual building of Skylab began, which was in 1969. Before that, NASA had been working on other potential space stations such as the Manned Laboratory Orbiter, which was never actually built. Many of the space stations that were suggested never got beyond simple sketches.
NASA launched Skylab on May 14, 1973; the space station was damaged during launch when a meteoroid shield and one of the two solar panels tore off due to vibrations. Since the station was designed to face the Sun, in order to get as much power s possible, and the shield was ripped off, the station rose to 52°C. Scientists had to move the space station and fix it before astronauts could stay on board.
The first manned mission to the station was on May 25 and lasted four weeks. Charles Conrad, Jr., Paul J. Weitz, Joseph P. Kerwin were the crew members for the first mission. Part of the mission involved fixing the station to make it habitable. During the mission, the crew conducted a number of experiments, including solar astronomy and medical studies. Three EVAs (extra-vehicular activities) were completed as well.
The second manned mission, also known as Skylab 3, was launched on July 28, 1973. The crew consisted of Alan L. Bean, Jack R. Lousma, and Owen K. Garriott. The mission lasted 59 days and 11 hours. The crew of this mission carried out repairs on the space lab as well as performed scientific and medical experiments.
The third and last mission to the Skylab, the Skylab 4, was the longest at 84 days and one hour. Gerald P. Carr, William R. Pogue, Edward G. Gibson were the crew for the final mission. In addition to performing various experiments, the crew of that mission also observed the Comet Kohoutek. The crew did three EVAs which lasted a total of 22 hours and 13 minutes.
Skylab was in the sky for 171 days and orbited the Earth more than 2,476 times. The space station was abandoned after that mission. Scientists placed the space station in a stable orbit and shut down the station. They thought that the station would stay in its orbit for 10 years, but by 1977 they realized that it would not keep a stable orbit for that long. The debris of the Skylab reached Earth on July 11, 1979 when debris rained over the Indian Ocean and parts of Australia.
Astronomy Cast has an episode on space elevators.