Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of 169,950 pounds (77 t). Three manned missions to the station, conducted between 1973 and 1974 using the Apollo Command/Service Module (CSM) atop the smaller Saturn IB, each delivered a three-astronaut crew. On the third mission, an additional Apollo / Saturn IB stood by, ready for launch if needed to rescue the crew in orbit.

Skylab included an Apollo Telescope Mount (a multi-spectral solar observatory), Multiple Docking Adapter with two docking ports, Airlock Module with EVA hatches, and the Orbital Workshop, the main habitable volume of the station. Power came from solar arrays, as well as fuel cells in the docked Apollo CSM. The rear of the station included a large waste tank, propellant tanks for maneuvering jets, and a heat radiator.

The station was damaged at launch when the micrometeoroid shield separated from the station and tore away, depriving the station of most of its power, removing protection from intense solar heating, and threatening to make the station unusable. The first crew was able to save it in the first ever in-space major repair, by deploying a replacement heat shade and freeing the single remaining, jammed main solar array.

Numerous scientific experiments were conducted aboard Skylab during its operational life, and crews were able to confirm the existence of coronal holes in the Sun. The Earth Resources Experiment Package (EREP), was used to view the Earth with sensors that recorded data in the visible, infrared, and microwave spectral regions. Thousands of photographs of Earth were taken, and records for human time spent in orbit were extended.

Plans were made to refurbish and reuse Skylab, using the Space Shuttle to boost its orbit and repair it. However, development of the Shuttle was delayed, and Skylab reentered Earth's atmosphere and disintegrated in 1979, with debris striking portions of Western Australia.

After Skylab's demise, the focus shifted to the reusable Spacelab module, an orbital workshop that could be deployed from the Space Shuttle and returned to Earth. The next American space station project was Space Station Freedom, which was never completed, although it eventually led to the construction of the US Orbital Segment of the International Space Station, starting in 1998. Shuttle-Mir was another project, and led to the U.S. funding Spektr, Priroda, and the Mir Docking Module in the 1990s.

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