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Skylab
I INTRODUCTION
Skylab, first American space station. In 1973 the National Aeronautics and Space Administration (NASA) launched the 100-ton Skylab module into orbit around the earth from the Kennedy Space Center in Cape Canaveral, Florida. Each of the three crews of Skylab astronauts was launched separately in an Apollo command and service module (CSM), and they stayed in Skylab for periods of 28, 59, and 84 days, respectively. The Skylab astronauts proved that it was feasible for humans to live and work in a weightless environment for extended stays without suffering ill effects. Astronauts also made key repairs to Skylab in space, paving the way for future repairs of satellites from the space shuttle. In addition, the Skylab astronauts successfully completed experiments on solar physics, earth observations, and crystal growth in zero gravity.
II SPACECRAFT AND SUPPORTING SYSTEMS
The main portion of the Skylab space station was the 27 m (89 ft) long orbital workshop. This two-story structure was constructed inside the converted second stage of a Saturn 1B rocket. One workshop floor provided living quarters for the crew and was divided into four sections: the sleep compartment, the waste-management compartment, the wardroom, and the experiment work area. The second floor was devoted to other scientific experiments that required large areas or needed external views. Solar arrays provided electrical power and were located on opposite ends of the long workshop.
Skylab's Apollo telescope mount (ATM) was the first manned solar observatory put into space. It was composed of eight integrated telescopes that studied the sun's corona, or wispy-looking outer atmosphere (see Sun). The ATM had its own solar arrays to use as independent power sources and its own guidance and control system.
The multiple docking adapter (MDA) was a cylindrical structure about 5.2 m (about 17 ft) long and 3 m (10 ft) in diameter that was used to link the Apollo CSM to Skylab. The MDA enabled the transfer of astronauts, equipment, power, and electrical signals between the CSM and Skylab. The MDA had two docking ports, hatches designed to lock with the Apollo CSM. One port was used for normal operations while the second acted as a backup.
Positioned between the MDA and orbital workshop areas was the airlock module, which provided an area for the crew to perform space walks, or extravehicular activities (EVAs), outside the space station. This module also contained control panels for electrical power, temperature control, telecommunications, data handling, and data recording.
The Apollo CSM, the same craft used for the lunar landing programs, provided transportation to and from Skylab for the astronauts. The CSM also enabled the astronauts to store and return experiments, as well as the accompanying data, to researchers on the ground. When the CSM was docked with Skylab, all CSM systems except communications were turned off to conserve energy.
Skylab and its crews were launched into orbit by Saturn rockets developed for the Apollo program. A two-stage Saturn V rocket sent the unmanned Skylab module into orbit. Smaller Saturn 1B launch vehicles carried the three crews in Apollo command and service modules to rendezvous with Skylab.
III MISSION HIGHLIGHTS
During the launch of the unmanned Skylab on May 14, 1973, a protective meteorite shield was ripped off, damaging the solar power arrays and causing the temperature within Skylab to soar. The crew of the first manned Skylab mission (Skylab 2), Pete Conrad, Joe Kerwin, and Paul Weitz, was originally scheduled for launch on May 15, 1973, but it was delayed until May 25, 1973, while NASA engineers devised possible repair scenarios. After a rendezvous with Skylab, the crew erected a makeshift parasol to act as a heat shield that reduced Skylab's internal temperature to a habitable level. On June 7, after repeated failures, astronauts finally succeeded in freeing the solar array jammed by remnants of the meteorite shield, allowing the onboard batteries to recharge with solar power. The crew of Skylab 2 proved that astronauts could perform tasks in space that could not have been managed by machines.
The second Skylab crew (Skylab 3) of Alan LaVern Bean, Owen Garriott, and Jack Robert Lousma was launched on July 28, 1973. While on board Skylab, the team conducted many more scientific experiments than had been planned. They observed and photographed severe weather situations on the earth, logged many hours of solar viewing, and accomplished numerous biomedical experiments. Among the biology studies was an experiment designed to learn if weightlessness would affect the way a spider builds its web. The crew also completed three EVA sessions to make further repairs to Skylab hardware and to tend to experiments and film canisters from the cameras photographing the earth.
Gerald Carr, Ed Gibson, and Bill Pogue made up the third Skylab crew (Skylab 4), launched on November 16, 1973. The astronauts completed numerous planned experiments and performed four EVAs. They also observed the comet Kohoutek, which some astronomers predicted would be a spectacular sight from the earth. Kohoutek actually appeared fairly dim from the earth, but from space it was bright and clear. The crew adapted well to their 84 days in space, despite experiencing physical changes such as slight height increases and reduction in muscle mass due to the lack of gravity. Biomedical data from the Skylab 4 crew's extended stay proved very useful to NASA for future mission planning.
After the Skylab 4 crew splashed down in the Pacific Ocean in their CSM, the Skylab module stayed unoccupied in orbit for over five years. It reentered the atmosphere in July 1979, disintegrating from the heat of friction. NASA technicians steered its reentry to the Indian Ocean, but some Skylab debris hit remote areas of Australia—no one was injured. Overall, NASA considered the Skylab program to be highly successful and to have provided many lessons applicable to further human missions in space.
Contributed By:
Stephen Garber
Skylab from Above
Skylab 4 astronauts took this photograph of the United States Skylab space station over the cloud-covered earth from their Apollo spacecraft as they prepared to return home on February 8, 1974. The sheet of gold-colored material stretched over the station is a makeshift sun shield that the astronauts of Skylab 2 set up to replace a sun and micrometeoroid shield that fell off during launch. As the shield fell, it knocked loose a winglike array of electricity-producing solar panels that was supposed to be in the same position on the left as the remaining array is on the right.
NASA
