Skylab
- Alternative meaning: research facility in the South Pole Station
America's first space station, the 75 ton Skylab was launched May 14, 1973 by a two-stage version of the Saturn V booster (the SL-1 mission). Severe damage was sustained during launch, including the loss of the station's micrometeoroid shield/sun shade and one of its main solar panels. Debris from the lost micrometeroid shield further complicated matters by pinning the remaining solar panel to the side of the station, preventing its deployment and thus leaving the station with a huge power deficit. The station underwent extensive repair during a spacewalk by the first crew, which launched on May 25, 1973 (the SL-2 mission) atop a Saturn 1B. Two additional missions followed on July 28, 1973 (SL-3) and November 16, 1973 (SL-4) with stay times of 28, 59, and 84 days, respectively. The last Skylab crew returned to Earth on February 8, 1974.
Skylab was actually the refitted S-IVB third stage of a Saturn V booster, a leftover from the Apollo program originally intended for one of the canceled moon landing missions (Apollos 18-20). A product of the Apollo Applications program (a program tasked with finding long-term uses for Apollo program hardware), Skylab was originally planned as a minimially-altered S-IVB to be launched on a Saturn IB rocket. The small size of the IB would have required Skylab to double as a rocket stage during launch, only being retrofitted as a space station once on-orbit. With the cancellation of Apollo missions 18-20 a Saturn V was made available and thus the "Wet Workshop" concept, as it was called, was put aside and Skylab was launched dry and fully outfitted. Skylab's grid flooring system was a highly visible legacy of the wet workshop concept.
All told, Skylab orbited Earth 2,476 times during the 171 days and 13 hours of its occupation during the three manned Skylab missions. Astronauts performed ten spacewalks totalling 42 hours 16 minutes. Skylab logged about 2,000 hours of scientific and medical experiments, including eight solar experiments. The coronal holes in the Sun were discovered. Many of the experiments were on the astronauts' adaptation to extended periods of microgravity, and each Skylab mission set a record for the duration of time astronauts spent in space.
Following the last mission the Station was positioned in a parking orbit expected to last at least 8 years. Increased solar activity heating the outer layers of the earth's atmosphere and thereby increasing drag on the Station led to an early reentry on July 11, 1979. Skylab disintegrated over Western Australia and the Indian Ocean, casting large pieces of debris in populated areas (fortunately, the only casualty being an Australian cow). The reentry prevented any further use by the then unfinished Space Shuttle as was envisioned by some at NASA.
Two flight-quality Skylabs were built, the second, a backup, is on display at the National Air and Space Museum in Washington, DC.
