Think of a long term base in space and everyone thinks of the International Space Station which has been the longest and most successful space program so far. But the hard-learned lessons that have kept the ISS continuously manned for over 20 years came from our very first attempt to live in space longer than just a few weeks with Americas first orbiting space workshop, Skylab.
However, Skylab became known more for the things that went wrong than the things that went right, problems that started just minutes into its launch and then years later just before it burned up. This is the story of Skylab and why it’s probably one the most important space mission we’ve ever done.
Now whilst we had shown that we could get to and land a man on the moon, the total amount of time we had spent in space on each apollo mission was still very short. The longest mission, Apollo 17 spent just 3 days on the surface and just 9 days travelling in space.
The talk at the time was that this could be the springboard to visiting other planets and in particular Mars.
This is the equivalent of someone making their first voyage in a sailing a dingy across the 34 km of the English channel and then deciding that the next one would be across the 5000km of the Atlantic ocean.
Whilst the moon is 384,000km away and about 3 days travelling time, to get to Mars takes about 7 months one way and then the same back again. We had no idea of what living in the weightless conditions of space for well over a year would do to the human body or if it could be done at all.
Well before we ever got into space, the use of a space station as a staging post for a trip to Mars had been discussed by Werner Von Braun in his 1952 book “Project Mars” and up until the 1960s it was thought that a space station of some sort would an important early step in space exploration.
However, the politics of the cold war dictated that the US should beat the Soviets to the Moon by the end of the decade and the idea of a dedicated space station was put to one side.
Although the US may have won the race to the moon the Soviets were the first to put a space station into orbit with the ill fated Salyut 1 in 1971. However, it had to be abandoned by its Soyuz 11 crew after 23 days due to problems including a fire in and the crew were killed by asphyxia whilst returning to earth when a valve in their Soyuz capsule failed and they remain the only people so far to have died in space.
Back in the US, Von Braun who had started out in the 1950s with the idea of a large rotating space station like that we see in the film 2001, had already worked out plans which would become part of the Apollo Applications Program to convert the second stage fuel tank of a Saturn rocket into an orbital workshop and with the cancellation of the later Apollo missions 18, 19 and 20, it freed up the now spare Saturn’s to create Skylab and also use the Apollo command & service modules to transport the crew to and from it.
Skylab would fill in the gap between Apollo and the space shuttle which was due in 1979. It would not only be a laboratory to find out how living in space would affect the human body, it would also carry the Apollo Telescope Mount and solar observatory to study the sun in both the Ultraviolet and X-Ray spectrum outside of the earth’s atmosphere, something that would become prescient of Skylab’s ultimate fate in 1979.
Skylab was launched on May 14th 1973 to be followed by the crew on another launch the next day but almost immediately it ran into problems when the micrometeoroid shield / sun shade accidentally deployed during the launch which was immediately ripped off by the slipstream as it travelled at several thousand km per hour.
Once in orbit and within an hour of the launch more problems became apparent, with no heat shield the temperature of the workshop was rising dramatically and the pair of solar arrays were not functioning correctly which later turned out that one had been pulled off by the departing sunshade.
NASA was now into a repair mission and had to delay the next day crew launch whilst they figured if and how it was possible to fix the problems and save Skylab.
Over the next 10 day’s teams around the US worked day and night to come up with a solution to fix the missing solar shield. The idea was to make a parasol that would be attached to the side of the workshop and then open it up to provide the shade required. As this was being done the backup crew practised the operations in the Skylab underwater simulator to both fit the parasol and fix the solar array.
10 days later the crew mission of Skylab 2 lifted off to try and rescue the $2.5 billion program, if they couldn’t fix the problems that could spell the end of Skylab.
Nothing like this had been done before, on the Apollo 13 mission the crew had managed to jerry-rig CO2 scrubbers together with what they had around the command module. On the Skylab mission, they would be working in space and although they had an idea what was wrong they wouldn’t know exactly until they got there.
Once the crew arrived and on a televised fly around they confirmed that the solar shield was gone as well as one of the solar arrays and that the other was jammed by a strap that was part of now missing solar shield.
The crew managed to fix the parasol in place and release the stuck solar array, bringing down the temperature in the workshop to acceptable levels and providing enough power for the mission to continue.
NASA learned that it was possible to work in space and fix problems that relied upon the crews initiative, something that would prove invaluable in the future for not only the assembling the ISS but for fixing the Hubble Space Telescope, another multi-billion dollar program that had to be fixed in space.
Once Skylab was functioning it could carry on work but it was hardly what you called luxurious. It was basically a giant tin can in which the crew would, eat, sleep and work, with one window, onboard excrement store, and somewhat bland food.
This large open space allowed them to do things that are not possible now on the ISS such as running around the wall and doing acrobatics. One of the things they discovered was that if someone was spun around in a chair they would not get dizzy like they would doing the same on earth, this showed that the inner ear relied on gravity to work.
Hundreds of experiments were carried out over the three missions on everything from exercise in space to earth resources looking down at the earth to material sciences like welding in space and growing crystals.
Each of the three crewed mission stretched the limit of human spaceflight endurance with skylab 2 lasting 28 days, skylab 3 56 days and skylab 4 for 84 days.
For the first time, we had a place to conduct experiments into all aspects of living in space for longer periods of time. Not only into how it affects the human body but how we could work in microgravity and how it affects materials and processing of things that would be needed like growing plants for food.
There were also student requested experiments like bringing spiders on board to see if they could build their webs in zero gravity. In fact it only took them a day or so go from making a chaotic mess of a web to making one that looked pretty much like they did on earth. One astronaut commented that they adapted to zero-gravity a lot quicker than humans and without the months of training.
Skylab had enough oxygen, food and water to last 24 man-months though in the end they only used 16 months of the supplies.
Before departing for the last time, the Skylab 4 crew left food and provisions for the next crew, which never happened, and left the hatch unlocked. They also used Apollo Command and service module to boost the orbit by 11km and leaving it in a parking orbit.
It was known that without a further booster operation skylab would eventually fall back to earth but this was not expected to occur until about 1983 and the Space shuttle was due to come into service in 1979 to boost skylabs orbit.
To do this the Teleoperator Retrieval System or TRS was ordered by NASA in 1977 for use in late 1979. This was a remotely controlled space tug that was designed to move payloads around in space and boost or de-orbit spacecraft or satellites.
The idea was that Skylab could be saved and be used as the core of a new larger space station.
But despite having the worlds best sun observatory on Skylab, NASA ignored warnings in 1973 by the British mathematician Desmond King-Hele of the Royal Aircraft Establishment (RAE) that it would return in 1979 and again by NORAD in 1977 who also revised their date to mid-1979 due to the effect of the largest increase in solar activity in a century.
Basically, with more energy coming from the sun, the more earth’s upper atmosphere heated up and this expanded outwards causing slightly more drag on Skylab. This would cause it to slow down, only very slightly but enough lower its orbit more quickly than expected and instead of deorbiting in 1983 it was now going to be some time in 1979.
Problems with the space shuttle meant that it was going to be delayed and would not be available to take the TRS to boost Skylab’s orbit so the TRS was cancelled. The TRS could have been launched on a Titan or Atlas Agena and controlled from the earth but the idea was also dropped as budgets were cut and Skylab was left to a fiery fate a few years later.
The debacle that was Skylab returning to earth also showed that NASA needed to learn lessons on how to predict and handle the return of a large piece of what was now space debris.
There was a plan to have fuel onboard Skylab to allow it to have a more controlled re-entry but that was later dropped because of the fear that it could be a danger to the crews onboard, this left NASA with less control where it would eventually end up on the earth.
This caused a media frenzy as people who were under Skylabs flight path were concerned that it could fall on them.
A few hours before the event NASA adjusted skylabs orientation to take it on a path that would fly across the US and drop into the southern Atlantic about 1300 km south-southeast of Cape town, South Africa to avoid flying over the more densely populated areas of Europe and on to China.
However, due to a 4% margin of error in the calculations and that the main parts of Skylab took much longer to burnup than expected, it carried along its flight path and over the southern Indian ocean where parts of it fell but some continued onwards to southwestern Australia where they fell over an area stretching from the town of Esperance on the coast to Rawlinna some 300km in a north-easterly direction.
Many pieces were found by local people with some saying that NASA had planned it to land there rather than in the US because it was sparsely populated but in reality, you can see that it was just at the end of its flight path and that if it had been controlled more accurately with onboard fuel it could have been dropped in the ocean much more accurately.
Although it was fraught with problems, NASA was able to make good on what could have been an expensive and humiliating failure and apply what it learned to future missions.
If Skylab had been lost just after its launch it would have set us back years and even with the Space Shuttles Extended Duration Orbiter program which was never fully utilised for month-long durations, it still wouldn’t have compared to the 510 man-days which were spent on Skylab.
The knowledge gained through NASA was open to everyone in the world and soon the Soviets would use it to help build a succession of new Salyut and Mir space stations culminating in the Zvezda which became the core of the Russian part of the ISS. #
This along with the modules from the US, Europe and Japan forms the basis of what we know about individuals continuously living in space for almost 2.5 years which will be invaluable for travelling to Mars in the not too distant future and which is why it could be said that Skylab is probably the most influential space program so far.
It was plagued with problems from the start but it turned out to be one of the most important influential space programs we have ever done. Skylab unintentionally showed us that we could fix major unexpected problems working in space and that we could survive in space for a long periods of time and paved the way for the ISS. This is the story of Skylab, the first and so far only US space station.