The International Space Station has been in operation since 2000. But America’s very first space station was in fact SKYLAB. It helped pave the way for permanent operations in low-Earth orbit over 50 years ago. Skylab spent six years in orbit from 1973 to 1979, with three successive three-man crews on board for a record setting 28, 56 and 84 days in orbit. The 169,950-pound space station included both an orbital workshop and a solar observatory.
Each crew, consisting of a commander, pilot, and scientist, was transported to the station using Apollo-era Saturn IB rockets. Astronauts conducted 270 experiments in biomedical sciences, solar astronomy, earth observations and materials processing. Most importantly, for the first time, astronauts tested their physiological responses to long-term space flight.
Skylab’s life came to a dramatic and tragic end. Its decaying orbit, due to atmospheric drag, caused it to prematurely re-enter the Earth’s atmosphere. It broke up and scattered large chunks of debris over the Indian Ocean and Western Australia in 1979. What happened in between however, paved the way for the Space Shuttles and ISS. Without Skylab, neither would have been possible.
The Skylab project began as part of the Apollo Program in 1968 to develop human space missions using technology originally developed to land astronauts on the moon. Experience gained from Apollo provided a foundation, but Skylab demanded both innovation and ingenuity. NASA had considered ideas for an orbiting space station long before Skylab launched.
In the 1960s however, the agency focused on President Kennedy’s moonshot space race with the Soviet Union.
As Apollo missions began to wind down in the early 1970s, the famous rocket engineer Wernher von Braun, proposed building a space station out of an unused second stage rocket. As it turned out, the hydrogen tank of the Saturn S-IVB stage offered ample room for setting up an orbital workshop. When it became apparent that several Saturn V rockets would remain unused after the Apollo 17 mission, NASA decided to use one of them to launch Skylab into orbit.
Skylab consisted of 4 major components: the Orbital Workshop (OWS), Airlock Module (AM), Multiple Docking Adapter (MDA) and Apollo Telescope Mount (ATM). The AM allowed astronauts to conduct spacewalks and provided an airlock between the MDA and OWS. The MDA included two docking ports for Apollo spacecraft, which acted as taxis for the astronauts. The ATM contained telescopes for solar observations and four solar arrays for power.
The Orbital Workshop was the heart of the station and served as the main working, living and sleeping crew quarters. It contained exercise equipment, galley, zero G shower, sleeping bags and scientific experiment. Two large solar arrays would provide 12.4 kilowatts of power. Altogether, the OWS contained equipment, provisions and quarters to support three-person crews for up to 90 days each.
Skylab was launched from the Kennedy Space Center on 14 May 1973.
Shortly after liftoff, a large micrometeoroid shield on the station, designed to both protect the workshop and act as a thermal blanket, began to loosen in the vibrations of launch. Within seconds, aerodynamic forces stripped the shield completely away. As the shield tore off, one of two main solar arrays partially began to deploy too early. When retro rockets fired to separate the 2nd stage booster from the station, exhaust from the rockets impacted the partially deployed solar array and ripped it off completely!
Once in orbit, more problems were soon detected by a stunned mission control. The opposite solar array, while still attached to the station, had been tangled in debris and failed to deploy. The missing micrometeoroid shield exposed the station to higher levels of solar radiation. Temperatures inside the station rose to an unlivable 126 F (52 C).
Fortunately, the four solar arrays on the solar telescope deployed as planned, but they generated only 25 watts of power. This at least allowed controllers to operate the station from the ground, until repairs could be made by astronauts. If they oriented the station panels toward the sun to maximize power, temperatures rose too high inside. A rotation that minimized heat build-up significantly reduced power generation.
The first Skylab crew, scheduled to lift off the next day, was delayed while tools and techniques quickly had to be developed to repair the crippled station. The launch of the first crew was delayed 10 days as astronauts Charles “Pete” Conrad, Paul Weitz and Joseph Kerwin began training for their revised mission to make the station habitable. The astronauts practiced using special tools to unjam the remaining solar array to allow it to provide electrical power.
On 25 May 1973, the first Skylab crew lifted off from Kennedy Space Center.
They carried with them new solar shades and a variety of cutters and tools designed to free the remaining jammed solar array. With an internal temp. well over 100 degrees F, astronauts could spend only short periods of time inside the station. On their second day, the crew was able to spacewalk and deploy a solar shade, known as the ‘Parasol’. The 22×24 ft sheet, composed of mylar and aluminum, reflected enough solar energy to lower the internal temp. to tolerable levels.
The crew’s next challenge was to deploy the last solar array during a second spacewalk. However, initial attempts failed as a metal strip holding it down refused to give way. Team members vented their frustration with four-letter words, realizing the tools sent up with them would not work. A second attempt a week later, successfully released the solar panel. Astronauts were able to cut the metal jamming the solar wing. Using a rope sling, they forced the array to fully deploy, finally providing electrical power.
While the incident was frustrating for the crew and team, it demonstrated that it was possible to fix badly damaged space hardware while in orbit. These lessons-learned were later adapted by the Shuttle for repairing the Hubble Space Telescope in orbit. With the station back on track, the crew was able to focus on their mission – materials processing in microgravity, Earth observations, solar astronomy, and most importantly, proving humans could live and work in space for extended periods.
Despite the added workload required to repair the station, the first crew was able to complete nearly all planned scientific objectives before returning to Earth after 28 days. Following splashdown, NASA had high praise for the crew and the entire team: “For the first time, a crew of astronauts has returned from an extended tour in a space laboratory.”
Skylab’s 2nd mission launched in July 1973, with Alan Bean, Owen Garriott and Jack Lousma aboard. With problems behind them, the crew focused on experiments ranging from the crew’s exercise time to nutritional requirements to daily hygiene schedules. Everything came under scrutiny. The crews also focused on science. The solar telescope allowed the astronauts to observe solar flares in action, and even Comet Kohoutek as it swung close to Earth. This second crew returned to Earth in September 1973 following 59 days in orbit.
The third and final Skylab mission, with astronauts Gerald Carr, Edward Gibson and William Pogue was launched in November 1973 and extended to 80 days. Skylab’s second crew had exceeded their performance expectations, prompting NASA to assign the third crew with even longer, laborious tasks. Things weren’t always that smooth between mission control and the astronauts. Skylab’s third team complained about being overloaded with too many tasks and seemingly superhuman expectations.
Skylab’s last crew left in February 1974, leaving the station in orbit unmanned.
NASA planned to bring more crews into orbit, but budgetary shortfalls and the Shuttle program turned attention elsewhere. An effort to send an early shuttle mission there also fell through. Skylab was parked in an orbit expected to last at least 8 years. It was planned to use the 2nd shuttle mission to add a propulsion module to Skylab, but that did not happen either.
Due to intense solar activity heating up the Earth’s atmosphere, causing drag on the station, Skylab’s orbit decayed faster than expected. NASA was faced with its inevitable fall to Earth. They adjusted the station as best as they could to splash down in an ocean, so it wouldn’t hit populated areas upon reentry. On 11 July 1979, Skylab re-entered Earth’s atmosphere. Large pieces of debris broke off the station. It fell over the Indian ocean and parts of populated western Australia. Thankfully nobody was hurt.
America was not alone in earth orbit. When the Soviet Union lost the race to the moon, they instead focused on their own space station program. There were no less than six Salyut, single-module space stations in successively in orbit from 1971 to 1986. This was followed by the very successful Russian Mir modular space station in orbit for 15 years from 1986 to 2001 with crews of up to six cosmonauts.
Skylab’s demise marked a temporary stop to NASA’s work on long-duration spaceflight. Through the lens of the successful ISS, Skylab is not a well-remembered in the public eye. It was not until the 1990’s that the agency resumed long flights during the Shuttle-Mir program in partnership with Russia. This laid the groundwork for the 16-nation International Space Station in 2000. In 2016, NASA astronaut Scott Kelly and Russian cosmonaut Mikail Kornienko spent a year aboard the ISS.
Despite nearly catastrophic problems, Skylab proved highly successful and completed all of its major objectives, proving that humans could productively work for prolonged periods in orbit. As a result of Skylab, astronauts today can candidly air concerns about workload and distance from family life– without repercussions. Because of Skylab, astronauts follow a strict exercise regimen of about two hours a day on a treadmill, exercise bike or weight lifting machine. This sort of exercise reduces bone loss, muscle atrophy and other medical problems in spaceflight.
Made possible by both its ground crew and nine astronauts, the importance of Skylab’s accomplishments for the future of human spaceflight are clearly evident. “It contributed to an orderly transition from the Apollo era to the space shuttle fleet in 1986 and helped pave the way for long-duration missions in low-Earth orbit aboard the ISS.” – NASA
Two flight-qualified Skylabs were actually built by NASA in the 1970s. The second, Skylab B, was never used. You can see it today, proudly on display at the Smithsonian’s cavernous National Air and Space Museum on the mall in Washington, DC.