Skylab was the first space station operated by the United States. It spent six years orbiting Earth until its decaying orbit caused it to re-enter the atmosphere. It scattered debris over the Indian Ocean and sparsely settled areas of Western Australia.
Three crews successfully lived on board the station for several months each. The last crew spent 84 days in orbit — an American record that stood until the shuttle era. [Photos: Skylab, the 1st U.S. Space Station]
Various NASA centers had kicked around ideas for a space station for years before Skylab launched. However, the agency was very focused on the space race and moonshots that dominated public consciousness in the 1960s. Money for other endeavors was not as available.
As Apollo began to wind down in the early 1970s, NASA began an Apollo Applications Program to fly unused hardware from the moon program. One idea, proposed by famous Apollo rocket engineer Wernher von Braun, would be to build a space station out of an unused rocket stage. The design evolved over the years as NASA struggled with reduced funding.
Skylab finally aimed for space on May 14, 1973. However, a meteoroid shield that was supposed to shelter Skylab accidentally opened about 63 seconds into the launch. The still-thick atmosphere tore the shield off, plunging Skylab into a serious situation. The facility experienced communications problems with the antenna as a result of the incident, but that was the least of the agency's worries.
"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," NASA wrote.
Workers at NASA's Marshall Space Flight Center scrambled to stabilize the station. Among other measures, they put the station in an attitude that would minimize overheating, and came up with ways to cope with the station's reduced power situation.
Meanwhile, the first crew – led by Apollo 12 commander Pete Conrad – would need to make the station habitable before they could get to work. The crew's first challenge during the spacewalk, just hours after launch, was deploying the solar array, but initial attempts met with no luck as a metal strip holding it down refused to give way.
Crew members emerged from an expected communications blackout in a foul mood, according to an official NASA account of the mission. "The astronauts were venting their frustration with four-letter words, while Houston repeatedly tried to remind them that communication had resumed," NASA wrote.
Realizing the tools they had with them that day would not work, Conrad abandoned the exercise and focused on trying to dock his spacecraft with the station. Unfortunately, the docking mechanism failed and the crew had to depressurize the spacecraft and bypass electrical connections to achieve it.
In subsequent days, Conrad's crew erected a sun shade, successfully deployed the stuck array, and began operational work aboard the station. While the incident was frustrating for the teams involved, it also demonstrated that it was possible to fix a badly damaged space station while it is in orbit.
The psychology of astronauts
With the worst of the mechanical problems behind, NASA and the three Skylab crews focused on matters pertaining to long-duration spaceflight. Everything from the crew's exercise time, to nutritional requirements, to scheduling, came under scrutiny and debate.
Skylab's second crew, led by Apollo 12 moonwalker Alan Bean, impressed NASA with its productivity. The crew finished its assigned tasks much faster than expected, and clamored for more. While the pace was impressive, it set within NASA some false expectations for how much a group of astronauts could accomplish.
Things weren't always that smooth between the ground and space. Skylab's third crew in particular complained repeatedly about being overloaded with tasks and superhuman expectations. Some have said the crew did a mutiny in orbit, although others characterize it more as a temporary refusal to do more work.
Whatever the situation, the unhappiness prompted a discussion between the ground and space where the two sides brought their mutual concerns to the table. Things never got that bad again between the crew and the ground controllers, but none of the astronauts flew in space again.
The commander of the mission, Jerry Carr, later said he regretted having waited for several weeks before airing his concerns. "We swallowed a lot of problems for a lot of days because we were reluctant to admit publicly that we were not getting things done right," he said in a NASA account of Skylab. "That's ridiculous, [but] that's human behavior."
In between adapting to a longer mission, crews focused on the science. A solar telescope mounted on the station allowed the astronauts to observe solar flares in action, although an early crew member joked that he was left wishing for "supernormal" flares. One crew also observed Comet Kohoutek in space as it swung closest to Earth.
Skylab's last crew left in February 1974, leaving the station in orbit. NASA had planned to bring more crews into orbit, but financial concerns and the run-up to the shuttle program turned attention elsewhere. An effort to send the shuttle there also fell through.
The space station's orbit decayed faster than expected due to intense solar activity heating up Earth's atmosphere. NASA, faced with the inevitable, adjusted the station as best as possible so it wouldn't hit populated areas upon re-entering on July 11, 1979. A math mistake led to pieces falling in Australia, but fortunately nobody was hurt.
Skylab's end marked a temporary stop to NASA's work on long-duration spaceflight. However, the agency resumed long flights during the shuttle-Mir program and these days, regularly sends astronauts for months at a time on the International Space Station.
— Elizabeth Howell, SPACE.com Contributor