Skylab was a space station launched by NASA on May 14, 1973. It was a workshop, and solar observatory. The astronauts on board conducted many different experiments. When skylab was originally launched and deployed it was damaged and Skylab 2 (the numbering of crews started at 2, 1 was the unmanned launch of skylab) did the first major in space repairs to correct the problems caused at launch.
Skylab 4 was the third manned mission and the last crew ever to board the very first American space station. The mission started on November 16, 1973 and lasted for 84 days, with the crew landing back on Earth on February 8, 1974. The crew consisted of 3 astronauts: a commander, pilot and science pilot. The Skylab 4 astronauts performed scientific experiments in the areas of medical activities, solar observations, Earth resources, observation of the Comet Kohoutek.
Skylab sat empty from 1974 when the last crew left until July 11, 1979 when it re-entered Earth atmosphere and most of it landed/crashed southeast of Perth, Australia.