The Day Skylab Fell 

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Today marks the 25th anniversary of Skylab's famed reentry, though this is probably the only place you'll read about it.

When the third and final crew of Skylab departed the station, they left a time capsule--a collection of items chosen by scientists on the ground to see how they would withstand long-term spaceflight exposure. The plan was for the time capsule to be recovered in a few years, when the then-in-development Space Shuttle became operational. Perhaps the Shuttle would even be able to reboost Skylab, giving the station a new lease on life. With several important systems failing, Skylab became a ghostly derelict after the last crew left in February 1974. It was estimated at the time that Skylab could remain aloft for another nine years before drag from the tenuous wisps of atmosphere at its altitude forced it to de-orbit, plenty of time for a Shuttle rendezvous.
It was not to happen. Delay after delay pushed back the completion of the Space Shuttle, but, more importantly, greater-than-anticipated solar activity, which had been a boon to Skylab's solar research earlier, went on to bring about the station's end. The sun's heat was expanding the Earth's atmosphere more than expected, increasing its density at Skylab's altitude and thus the drag on the station. This unfortunate confluence of events sealed Skylab's fate: without intervention, it would make an uncontrolled reentry into the Earth's atmosphere and no one knew exactly where it would come down.
Weighing about 75,000 kilograms, Skylab was, at the time, the heaviest object ever put into Earth orbit. One study concluded that more than 300 pieces of the station would survive reentry, the largest being about the size of a desk and weighing as much as a small car.
When the time came for the station to reenter in early 1979, the media hype had reached a fevered pitch and people around the world were on alert. (One enterprising company called Chicken Little Associates offered a service predicting individuals’ risk of being hit.) Concern had been heightened by a recent crash of a Soviet satellite carrying nuclear materials in northern Canada, prompting NASA to issue assurances that Skylab contained no radioactive materials.
Plans were considered to attempt an unmanned reboost of the falling station, but the idea was nixed over cost issues. Eventually, NASA flight controllers were able regain enough control over the station to reduce the probability of it coming down in a populated area. This was largely successful, as much of the mass is believed to now reside on the bottom of the Indian Ocean. A considerable amount landed in southwest Australia near Perth, about a week before the Miss Universe competition was to be held there, thus providing even greater publicity to what really became a nonevent to everyone except those in SW Australia. The heaviest and most compact item, the large steel film vault, has never been found and is probably laying on the ground somewhere in the Australian outback!
On July 11, 1979, the vehicle made a fiery but largely uneventful return to Earth. People in southwest Australia were treated to sonic booms and a light show as pieces of Skylab showered down, but neither property nor human beings were hurt. There was a price to be paid, however. Australia reportedly fined NASA $400 because of the reentry—for littering!

:: :: 20:15 :: David :: [permalink] ::