Skylab: Everything You Need to Know

2013 marked 40 years since Skylab, NASAòÀÙs first post-Moon landings human spaceflight project, was sent into orbit. Here is an overview of this rather forgotten series of missions.

Prepared before launch, this beautiful diagram shows both solar arrays in place. (image credit: NASA)

So what was Skylab?

Skylab was the first and so far last all-American space station to orbit the Earth. It was EarthòÀÙs second space station after the Soviet UnionòÀÙs Salyut 1. Skylab grew out of the Apollo Applications Program (AAP), a 1960s plan to use the hardware developed to send astronauts to the Moon for other purposes. The AAP seemed reasonable and an obvious next step at the time, but budget cuts to NASA, improved technology for unpiloted missions and greater knowledge of how difficult space operations are rapidly made it obsolete. Skylab was the only element of the AAP to go ahead.

Skylab in orbit, note the missing solar panel and improvised fabric sunshade (Image credit: NASA)

Why is it worth remembering?

Skylab was the first NASA project designed to explore how space flight could expand and enhance human well-being on Earth (said NASA).ˆà The astronauts who worked on Skylab performed experiments and observations across many fields, including Earth observation, solar astronomy, stellar astronomy, space physics, geophysics, micro-gravity biomedical and biological studies and micro-gravity technology research. A series of projects designed by high school students were carried out on Skylab, to promote science and technologyˆà education. ˆàIn many ways it was a precursor to todayòÀÙs International Space Station. Note that NASA never described Skylab as a “space station”, preferring the term “orbital workshop”. At this time NASA officials still hoped to be allowed to build and operate a giant space station (by about 1980 or so) and did not want Skylab to see as a lower cost alternative to this more ambitious project (which in the end was never built).

Skylab at launch. This Saturn 5 was originally built to send Apollo 20 to the Moon (Image credit: NASA)

What was it like?

Skylab was big! About 35 meters (117 feet) long , Skylab (including a docked Apollo CSM) weighedˆà 90.6 tonnes (199 750 lbs). It is still one of the largest crewed spacecraft, outweighed only by Mir and the ISS. Unlike these later space stations, Skylab was launched in one piece rather than assembled from modules placed in orbit over years. ˆàThis was because Skylab was converted from the third stage of a Saturn 5 rocket which was completely outfitted with a workshop area and living quarters before launch. The crews visited Skylab and returned to Earth in Apollo CSM spacecraft launched by Saturn 1B rockets.

At one end of Skylab was a docking port for two Apollosˆà (though only one at a time ever visited) and the Apollo Telescope Mount. This was a complete observatory with its own X-shaped solar array for imaging the Sun in X-ray and ultra violet wavelengths. Skylab astronauts performed spacewalks to change the film in this instrument, transferring the exposed film to a lead safe for storage,

Its large interior volume made Skylab spacious and crew had freedom to move (and play) in this huge volume. A wire mesh grid separated the interior into a workshop and living quarters, making it the first two-storey space habitat.

Skylab as launched showing damage and a jammed solar panel. Power diverted from the ATM’s solar array made up for the missing solar panel.(Image credit: NASA)

Everything went fine then?

No! It was almost a total failure! During the Skylab’s launch, the airflow ripped a meteoroid shield clean off, taking one of two solar panels with it and preventing the other from unfolding. This damage resulted in reduced power for the station and caused its interior to overheat. When the first crew arrived 11 days later, their first task was to repair as much of the damage as possible. After several challenging spacewalks to make substantial repairs, including freeing the jammed solar panel, and fitting a huge custom-made parasol sunshade which cooled the internal temperatures to 23.8 degrees C (75 degrees F), the crew came on board. Very much forgotten today, these repairs were a very impressive achievement as the astronauts and the engineers on the ground saved a hugely expensive project from ignominious failure.

Astronaut Gerald Carr in Skylab. He and the rest of the crew of Skylab 4 grew imposing beards in their rocky sojourn in orbit. (Image credit: NASA)

Who were the Skylab crews?

Three separate three-man crews (these were still the days when the NASA astronaut corps was an all-boysòÀÙ club) occupied the Skylab workshop for a total of 171 days and 13 hours. Skylab missions included both rookies and veteran astronauts, including some who had walked on the Moon.ˆà The crews did nearly 300 scientific and technical experiments, including medical experiments on humans’ adaptability to zero gravity, solar experiments and detailed Earth resources experiments. The final crew set an endurance record of 84 days living in orbit. Confusingly the three missions were designated Skylab 2, 3 and 4 (Skylab 1 was the original launch).

What was life on Skylab like?

For those of us used to earthly comforts life on Skylab would have seemed Spartan but to the experienced astronauts who stayed there it was luxurious compared to earlier vehicles like Gemini and Apollo. There was space to move around, in fact space to lose things in. There was exercise equipment and sort of real food to eat, the space station even had a shower and toilet. Rather than wearing white overalls, crews sported ensembles of jackets, t-shirts and slacks of mustard-coloured fabric (it was the 1970s after all). There was no washing machine, so dirty clothes were simply discarded. For their leisure times, astronauts brought music on cassettesˆà (if you donòÀÙt know what these were ask your grandparents) and paperback books (permitted only after overcoming opposition from NASAòÀÙs safety gurus who feared books would be a fire hazard).

The final Skylab Apollo CSM. These Apollo spacecraft had white-painted Command Modules, unlike the foil-covered ones used on lunar flights and the Apollo Soyuz Test Program. (Image credit: NASA)

Was there a downside to living on Skylab?

Putting people in orbit is expensive so the mission planners tried to get as much work out of the crews as feasible, planning long and busy schedules of work. These seemed fine as planned on Earth. In practice, the astronauts discovered micro-gravity made everything slow and difficult. Work on Skylab often fell behind schedule.ˆà The final Skylab crew (Gerald P. Carr, Edward G. Gibson and William R. Pogue), all rookie astronauts, kept failing to complete tasks on time. They found mission control unsympathetic, and were told to work through their meal and rest times to catch up.ˆà Carr tried to negotiate a reduction in working hours, saying

On the ground, I donòÀÙt think we would be expected to work a 16-hour day for 85 days, and so I really donòÀÙt see why we should even try to do it up here.

The crew had been under a cloud from the start of the mission since they decided to conceal the fact that two of them had been violently spacesick. Unfortunately they had not realised Skylab was bugged and an open mike relayed their whispered plotting to Mission Control. Things never recovered from this frosty start, and the crew’s complaints about their workload fell on deaf ears. About six weeks into the 84 day flight, the Skylab 4 crew rebelled, turned off the radio and took an unofficial day off to relax and sightsee. These were all disciplined career military men, so things must have been bad for them to stage this protest. Obviously this orbital strike was career suicide and none of the trio ever flew in space again.

1978: Space Shuttle Columbia boosts Skylab into a higher orbit, saving the giant space station. Alas this never happened. (Image credit: NASA)

What happened to Skylab?

After the last crew went it continued to orbit Earth, but it was not intended to remain derelict, NASA maintained contact with the empty outpost in the hope it would soon be brought back to life.ˆà It was still stocked with air and water. Regular Space Shuttle flights were expected to begin in 1977 and there was a general belief that visiting Shuttle missions could easily refurbish and expand Skylab. Perhaps Skylab would have a second life as the core of a vast and elaborate orbiting base for future exploration. Unfortunately as we all know, the Space Shuttle development project was severely delayed. Worse still, mother nature conspired to doom Skylab. Solar activity caused our atmosphere to expand, so the space station met increasing drag as it circled Earth. Its orbit was clearly decaying and plans were made to redirect one of the Space Shuttle test flights to rendezvous with Skylab to fit a rocket motor to boost it into a higher orbit. Unfortunately Skylab was predicted to fall back to Earth before 1980 and it was clear that the Shuttle would not be ready in time.ˆà Its impending fate prompted rather more interest than its successful career as a research centre, but not the panic we would probably see today. The empty Skylab spacecraft fell to Earth on 11 July 1979, scattering debris over the Indian Ocean and Western Australia. Today recovered fragments of Skylab are in museums. A complete back up Skylab is on public display in the National Air and Space Museum in Washington DC.

Further reading

Living and working in space: a history of Skylab by W. David Compton and Charles D. Benson, National Aeronautics and Space Administration, Washington, D.C., 1983 (Link)

(Article by Colin Johnston, Science Education Director)