Skylab Operations Summary
The Skylab space station launched May 14, 1973, from NASA's Kennedy Space Center by a huge Saturn V launch vehicle -- the moon rocket of the Apollo Space Program. Sixty-three seconds after liftoff, the meteoroid shield -- designed to shade Skylab's workshop -- deployed inadvertently. It was torn from the space station by atmospheric drag. This event and its effects started a 10-day period in which Skylab was beset with problems that had to be conquered before the space station would be safe and habitable for the three-manned periods of its planned eight-month mission.
When the meteoroid shield ripped loose, it disturbed the mounting of workshop solar array wing No. 2 and caused it to partially deploy. The exhaust plume of the second stage retro-rockets impacted the partially deployed solar array and literally blew it into space. Also, a strap of debris from the meteoroid shield overlapped solar array wing No. 1 such that when the programmed deployment signal occurred, wing No. 1 was held in a slightly opened position where it was able to generate virtually no power.
In the meantime, the space station had achieved a near-circular orbit at the desired altitude of 435 kilometers (270 miles). All other major functions occurred as planned, including payload shroud jettison, deployment of the Apollo Telescope Mount (Skylab's solar observatory) and its solar arrays, and pressurization of the space station.
Scientists, engineers, astronauts and management personnel at NASA's Marshall Space Flight Center and elsewhere worked throughout the first 10-day period of Skylab's flight to devise the means for its rescue. Simultaneously, Skylab -- seriously overheating -- was maneuvered through varying nose-up attitudes that would best maintain an acceptable "holding" condition. During that 10-day period and for some time thereafter, the space station operated on less than half of its designed electrical system in the partially nose-up attitudes, and was generating power at reduced efficiency. The optimum condition that maintained the most favorable balance between Skylab temperatures and its power-generation capability occurred at approximately 50 degrees nose-up.
Skylab's achievements are a summary of the accomplishments of many ground-based teams, as well as its three separate crews that launched in Apollo-type command modules by Saturn IB vehicles on May 25, July 28 and Nov. 16, 1973. In Skylab, both the man-hours in space and the those spent in performance of extravehicular activities under micro-gravity conditions exceeded the combined totals of all of the world's previous spaceflights up to that time.
By deploying the parasol-type sun shield through Skylab's solar scientific airlock and later releasing workshop solar array wing No. 1 during an EVA, the first crew made the remainder of the mission possible. The second crew, also during an EVA, erected another sun shield -- a twin-pole device.
The effectiveness of Skylab crews exceeded expectations, especially in their ability to perform complex repair tasks. They demonstrated excellent mobility, both internal and external to the space station -- showing humans to be a positive asset in conducting research from space. By selecting and photographing targets of opportunity on the sun, and by evaluating weather conditions on Earth and recommending Earth resources opportunities, crews were instrumental in attaining high-quality solar and Earth oriented data.
All three crews demonstrated technical skills for scientific, operational and maintenance functions. Their manual control of the space station, their fine pointing of experiments, and their reasoning and judgment throughout their missions were highly effective. The capability to conduct longer manned missions was conclusively demonstrated in Skylab, first by the crew returning from the 28-day mission, and more forcefully, by the good health and physical condition of the second and third Skylab crews who stayed in weightless space for 59 and 84 days, respectively. Also, resupply of space vehicles was attempted for the first time in Skylab and was proven to be effective.
During their time in space, all three crews exceeded the operational and experimental requirements placed upon them by the pre-mission flight plan and schedule. In addition, the third crew performed a number of sightings of comet Kohoutek, which were not initially scheduled.
Following the final manned phase of the Skylab mission, ground controllers performed some engineering tests of certain Skylab systems -- tests that ground personnel were reluctant to do while men were aboard. Results from these tests helped to determine causes of failures during the mission and to obtain data on long-term degradation of space systems.
Upon completion of the engineering tests, Skylab was positioned into a stable attitude and systems were shut down. It was expected that Skylab would remain in orbit eight to 10 years. However, in the fall of 1977, it was determined that Skylab was no longer in a stable attitude as a result of greater than predicted solar activity.
On July 11, 1979, Skylab impacted the Earth's surface. The debris dispersion area stretched from the southeastern Indian Ocean across a sparsely populated section of Western Australia.