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Skylab

11th July 1979 – the sky was falling. Well, not the actual sky, but something was coming down from space that would crash land somewhere on Earth. Nobody knew quite where, or how destructive it would be – the world held its breath.

This was not a meteor, or even a small satellite – but an entire space station. Long before the International Space Station, even before the Russian Mir Station, came Skylab – which sounds like it should be the setting of a futuristic James Bond movie. Skylab was a solely U.S initiative that orbited the Earth between 1973 and 1979. In terms of what a space station should do, it was regarded as a success, but a combination of factors left it abandoned for five years, before plummeting back down to Earth much earlier than had been anticipated.  

On the 11th July 1979 eyes strained skyward. NASA had done its best to direct Skylab to an area in the South Atlantic Ocean where it could crash safely, far away from populated areas – but a miscalculation meant that it was actually coming down thousands of miles away. 

Origins 

As the 1950s drew to a close, American attentions began to focus on a moon landing – but they knew they were still a long way off. Many believed that a space station would be a logical first step to further space exploration. Wernher von Braun, whose brilliant work with rockets benefited both Nazi Germany and later the United States, had been pushing for this for years. Between 1952 and 1954 he had published a series of articles under the title – “Man Will Conquer Space Soon!” – in which he mused on the topic of a circular station 75 meters (250 feet) in diameter that could accommodate 80 people. Skylab never even remotely reached this size, but we’ve got to aim big right? Von Braun envisioned that future missions to both the Moon and Mars would depart from the station, but could also be used to carry out surveillance and help to predict the weather. 

The early 1960s saw plenty of ideas thrown around by NASA, with plans ranging from a collaboration of various spacecraft held together that could support two or three people, to a large station that could accommodate 24 people and would have a service life of five years. 

This being the time of the Cold War, you won’t be surprised to hear that the Department of Defence (DOD) also threw their hat into the ring and at first the idea of a joint venture seemed in the offering. However, when the DOD made it clear it was only looking for its own crewed facility ( I wonder why?), NASA and the DOD went their separate ways. In December 1963, the DOD announced their Manned Orbital Laboratory (MOL), which was designed to be a small space station used for photo-reconnaissance. NASA’s plans for a space station continued separately, but the two would compete for funds over the next five years, with MOL finally being scrapped in 1969. 

Wet or Dry

In 1964 Wernher von Braun proposed a station that would be built from the S-II second stage of a Saturn V rocket. This rocket was composed of four separate stages which would fire in succession to one another and had been designed to carry the Apollo program to the moon. His first design came to be known as a wet workshop and involved venting the S-II of its remaining fuel once it had reached orbit then inserting an equipment section inside the fuel tank. Essentially the station would be almost entirely inside the spent fuel tank of the S-II. 

This design was later adapted to use the S-IVB stage of the Saturn rocket with an airlock attached to the hydrogen tanks. A later launch would then bring other sections of the station including solar panels, the equipment section and docking adapter, and various experiments to be undertaken in space. 

It’s important to remember that this was certainly not the only NASA program that was gathering pace at the time. The Apollo moon landing program competed with the station program, now known as the Apollo Applications Program (APP), for funding. APP also included other planned initiatives such as moon mapping and base construction missions, but these were slowly stripped away. The lavish days of spending were coming to an end and there was a tightening of the budget. In 1967 APP received just $42 million ($325 million today) of the $450 million ($3.5 billion today) it had requested. 

The cancellation of Apollo missions 18 to 20 eventually freed up three Saturn rockets to be used for by APP, and while Von Braun’s initial concept would now have been possible, NASA settled on a design where stages 1 and 2 of a Saturn rocket would launch along with an already prepared mini station – known as a dry workshop. 

A Livable Space

What eventually become Skylab needed to provide astronauts with a livable environment for several months. An industrial design firm, Raymond Loewy/William Snaith, began making recommendations of how to best do this, including windows to view Earth from and a wardroom for meals and relaxation. Astronauts were consulted on what was and wasn’t important to them and stated they weren’t interested in TVs or video games but did want books and individual choices for music. 

Skylab (небесная лаборатория)
Photo by Niksoon, is licensed under CC-BY-SA

The food was also a major issue. Early Apollo missions had complained about the taste, blandness and composition of the food choices on the shuttles. Skylab made great strides in this area by prioritizing edibility over simple nutritional value. The station’s increased size in comparison to space missions meant that a greater variety could be provided. The menu aboard Skylab included 72 items, around 15% of which came frozen. Shrimp cocktail and butter cookies were popular on Skylab, while Lobster Newberg, fresh bread, processed meat products, and ice cream also featured regularly. 

Each astronaut had their own sleeping quarters, about the size of a small walk-in closet, with a shower and toilet separate to be used by all. And while we’re talking toilets, stool and urine samples to be studied back on Earth were incredibly important – so much so they received priority in the event of an accident and subsequent rescue mission. I mean, I’m sure they would take the astronauts first, but the crap would certainly be coming with them too. 

Skylab

Skylab used a customized version of the TC-1 computer, a version of the IBM System/4 Pi, which weighed around 45.4 kg (100 pounds) and used about 10% of the station’s electrical power. One of its most vital jobs was to control the pointing of the station to aid solar collection and during experiments. 

the Skylab Space Station Cluster
Photo by NASA Johnson is licensed under CC-BY-NC

The space station used a control moment gyroscope (CMG) as an attitude control device. This consisted of a spinning rotor and motorized gimbals (pivoted supports) that tilt the rotor’s angular momentum – which is the equivalent of linear momentum. Skylab was the first to use such a device in space. The CMG also acted to resist various forces either inside or outside the station which could affect it. These included gravity gradient, aerodynamic disturbance and internal movements of the crew. The CMG rotor was 21 inches in diameter, weighed 70.3 kg (155 pounds) and rotated at approximately 8950 revolutions per minute. 

Skylab weighed 77 tons in total – which is about the same as 13 adult elephants – had a length of 25.1 metres (82.4 feet) and a width of 17.0 m (55.8 feet ). Inside, it had a pressurised volume of 351.6 m3 (12,417 cu ft) – around one-tenth the size of an Olympic size swimming pool. Now imagine living in that space for months on end! 

Launch

In 1969 the McDonnell Douglas Corporation was awarded a contract to convert two existing S-IVB Saturn V stages and in 1970, the name was changed to Skylab. On 14th May 1973 a Saturn V rocket blasted off with the unmanned Skylab 1 onboard. It was a fairly bumpy ride with the micrometeoroid shield/sunshade and one of its main solar panels both destroyed shortly after take-off. Nevertheless, Skylab 1 made it. Shaken, a little damaged – but now in orbit. 

Skylab 2, this time along with a crew of three, launched on 25th May 1973 and reached Skylab 1 without incident. Much of their time on the station was spent repairing the battered shell of Skylab 1. A new parasol-like sunshade was installed that not only kept temperatures down but prevented the plastic insulation from melting inside the station, which would have released poisonous gases. 

The crew of Skylab 2 remained in orbit for 28 days. Skylab 3 followed on 28th July 1973 and remained there for 59 days, while Skylab 4 stayed 84 days after launching on 16th November 1973. Each Skylab mission extended the record amount of time spent in space by humans, beating the Soviet Salyut 1 which had remained in space for 23 days. The last Skylab crew returned to Earth on February 8, 1974. 

Operations Onboard

The astronauts aboard Skylab were kept busy. A normal day began at 6 am – those on Skylab 2 took one shower a week but quickly found that drying oneself in weightlessness, and collecting the excess water that had a habit of spaying everywhere was more hassle than it was worth. Subsequent missions chose to simply clean themselves daily using a wet washcloth. 

Breakfast was at 7 am and was typically done standing as they found sitting in microgravity had a habit of straining their stomach muscles – as did tying shoelaces and putting on socks. Before lunch, they would carry out repairs, experiments or tests, while also trying to fit in the recommended 90 minutes of physical exercise on the stationary bike or other equipment that had been included. Humans lose around 1% of bone mass every month while in space, so exercise was seen as a vital part of life on Skylab. Things continued much the same way after lunch, with dinner at 6 pm. After this, crews would carry out household chores, and often spent up to 90 minutes cleaning a day, while also preparing equipment for the following day’s experiments. 

Skylab came with a selection of books and music, a dart set and playing cards, but most agreed that the favoured spot to relax was the window that stared down at the Earth. 

Ten spacewalks took place on Skylab, totalling 42 hours and 16 minutes. Skylab logs recorded a total of 2,000 hours of scientific and medical experiments, 127,000 frames of film of the Sun and 46,000 of Earth. Experiments included photographing solar flares, and the existence of the Sun’s coronal holes (the darker patches on the sun with lower gas and energy levels) was confirmed by the photos brought from Skylab. While many of the experiments onboard looked into the astronauts’ adaptation to extended periods of microgravity, other experiments could be divided into the following:

  • Life science which included human physiology, biomedical research and circadian rhythms involving mice and gnats. 
  • Solar physics and astronomy focused mainly on sun observations, stellar observations and space physics while Skylab 4 followed the progress of Comet Kohoutek through space. 
  • Earth resources involved experiments with mineral resources and geology while the crew observed hurricanes and land and vegetation patterns back down on planet Earth
  • Material science saw some welding, brazing, metal melting, crystal growth but also focused on water / fluid dynamics in microgravity.

Change of Plans

As I mentioned earlier, the final Skylab crew left the station on 8th February 1974 – but they did not believe they would be the last. So sure were they that another mission would soon be docking at the station, the crew of Skylab 4 even left a welcome bag for the newcomers. The three crewed missions had used only 16.8 of the 24-man-months of oxygen, food, water on the station, which itself was believed to be space worthy until 1982 – nine years after its launch. And this wasn’t due to old or faulty equipment, the natural pull of Earth’s gravity meant that over a period of time an object orbiting would eventually be pulled closer to it and eventually enter the atmosphere.  

Skylab 5 was originally scheduled but was later scrapped, however, NASA still believed it had plenty of time before Skylab lost enough altitude that it would be sucked into Earth’s gravity. As you would expect of NASA, they even did plenty of calculations on it – but unforeseen changes meant that Skylabs life expectancy would be much shorter than previously thought – and a British mathematician Desmond King-Hele of the Royal Aircraft Establishment had already predicted it. 

In 1973, he had reasoned that because of an increase in solar activity, Skylab would de-orbit and crash in 1979, rather than the early 1980s that NASA had predicted. The problem was the sun’s solar activity had increased dramatically, to the second-highest seen in a century. The result meant that it was heating the outer layers of Earth’s atmosphere and increasing drag on Skylab. By 1977, North American Aerospace Defence Command made the same prediction, it was quickly becoming apparent that NASA had got its numbers wrong. The Battelle Memorial Institute in Ohio predicted that up to 25 tons of metal debris could land in 500 pieces over an area 4,000 miles long and 1,000 miles wide – it was an ominous forecast. 

NASA was now in a race against time. The new space shuttle was nearing completion, and it was hoped it would be ready in time to launch a mission to Skylab to fire its rockets and prolong its life by pushing it further out to space. But by December 1978, it became clear the Columbia Space Shuttle would not be ready in time.   

RE-ENTRY

The doomed Skylab quickly became a media sensation. A newspaper, the San Francisco Examiner offered a $10,000 prize for the first piece of Skylab brought to its downtown offices. NASA commissioned a report that stated the chances of it hitting a human was 1 in 152 and the chances of it landing on a city with 100,000 people or more was 1 in 7. Panic spread in many parts of the world, with the President of the Philippines going on live television to reassure a fearful nation. 

NASA announced re-entry would occur between 10th and 14th of July 1979, with the 12th being the most likely – nothing like a bit of mystery when tons of metal is about to appear from the sky. Shortly before re-entry, NASA adjusted Skylab’s orientation to minimize the risk of it landing on a populated area. Their chosen spot was 810 miles (1,300 km) south-southeast of Cape Town.

But once again things didn’t go according to plan. Due to a 4% calculation error, Skylab did not burn up as quickly as expected and came crashing down in Western Australia instead. But to be honest, if it was going to hit dry land, the emptiness of Western Australia might well be the very best place for it. Not only were there no injuries, as a result, but no property damage was recorded either. NASA had been incredibly fortunate, but they were cheekily fined $400 by the Shire of Esperance – for littering.

A CHAOTIC END

It’s easy to remember Skylab as the uncontrolled falling space station that could have flattened buildings and killed many – when the world watched the skies anxiously. But Skylab had also been a tremendous success. 

While not the first space station – that goes to the Soviet Salyut – Skylab undoubtedly extended our space adventure and laid the foundation of what was to come. As I mentioned earlier, it set three consecutive records for time spent by humans in space and was occupied for a total of 171 days. Experiments were done onboard, in particular, its solar observations pushed our knowledge of space further than ever. 

In total, Skylab spent 2,249 days orbiting the Earth and travelled around our planet 34,981 times. The distance the station had covered was also staggering, measuring 1,400,000,000 km (890,000,000 miles) – just a little more than the distance from Earth to Saturn.   

Skylab was a brilliant achievement at a time when the financial splurging of the 1950s was over. It may be remembered most for its chaotic, fear-inducing ending, but that makes the story all the more exciting. Those days in July 1979 when the world held its breath may have been the stuff of our worst nightmare, but it was the climax to a colossal project that had brought us closer to life outside of our planet than we had ever known. 

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