Skylab in deep trouble

The Skylab project grew out of a number of proposals dating back to the idea of an orbiting solar observatory which had been suggested in 1962, and von Braun’s ideas of the 1940s. George Mueller suggested the concept of using the casing of one of the lower stages as a space lab. Such a project would extend the life of the manned space flight network.

Skylab was made up of the Saturn Workshop (SWS), 15 metres long with a diameter of 6.7 metres. The SWS connected with an Airlock Module (AM) connected, in turn, to a Multiple Docking Adapter (MDA), 5.2 metres long by 3.2 metres in diameter. The MDA had two ports: one to to dock the visiting command module and one for rescue. The docking port allowed the astronauts access and also contained the control and display panels for the Apollo Telescope Mount (ATM). The four diagonal solar wings provided the power for the telescope and part of the power for the SWS, most of which would come from the solar panels mounted on beams which would extend at 90° from the SWS itself.

The Skylab 1 mission was launched on 14 May 1973. Lindsay:

Skylab 1 was the last Saturn V launched in the twentieth century. With the regular stunning successes of the Apollo launches, it was expected to be another copybook mission. It was – until just after launch. On a nice warm spring day, right on time, the SIC first stage thundered into life on Pad 39A at the Kennedy Space Center and lifted smoothly into the air. It looked another perfect launch, then 63 seconds later the flight engineers were startled to see their telemetry giving strange indications from the micrometeoroid shield and part of the solar array – it looked as though they had initiated deployment early. Atmospheric drag had torn the shield loose and a portion had jammed one of the workshop solar wings, and severely damaged the other solar wing. The staging rocket’s blast then tore the wing from its hinges and flung it into space to be lost.

Just over ten minutes after launch Skylab entered a nearly circular orbit above the Earth, and manoeuvred around until its centreline pointed to the centre of the Earth. Unlike Apollo, which rolled around on its way to the Moon to keep the temperatures evenly spread around, Skylab remained in one attitude throughout the orbit, the heat and cold being controlled by a micrometeorid shield using black, white and aluminium paints painted in a carefully tailored pattern to control heat losses and gains. This shield was lost, so the surface of the workshop was left exposed to the Sun, and the temperatures rose 93°C above the designed limits.

It is interesting that Skylab became overheated out in space – because Apollo 13 became unbearably cold when in trouble. Why the difference? First it should be understood that a passive body in space absorbs and radiates heat. If these are not equal the body will heat up or cool down to a stable temperature where the heat being received equals the heat loss, providing the conditions remain constant. Although there are other factors, the simplistic explanation is Skylab lost its temperature controlling thermal heat shield which was carefully designed to balance the heat absorption and losses in its planned environment. The Laboratory was also orbiting very close to Earth. As the Earth radiates roughly the same amount of heat it receives, particularly in the infrared band, Skylab was receiving heat energy from both the Sun and Earth while in daylight, so its temperature went up.

Apart from being away out in space beyond the Earth’s reflected heating influence, Apollo 13’s electrical equipment was shut down to an absolute bare minimum, so again the carefully planned temperature control for its environment was out of balance. With the lack of internal heat being generated by the spacecraft’s electronics, Apollo 13’s temperature went down.

After nearly 26 minutes into the flight the solar panels for the telescope mount were successfully set up, but when they tried to extend the two big wing‑like solar panels to provide the electrical power for the workshop just before Carnarvon, nothing seemed to happen. When Skylab came up over the horizon, Carnarvon found that instead of 12,400 watts of power there was a paltry 25 watts! As these panels supplied 60% of the power to run the laboratory, added to temperatures going up by the hour, and there was also a gyro malfunction, Skylab was in deep trouble – and the mission had just begun!

EGIL, the flight controller in Houston for the spacecraft electrical and environmental systems at the launch, was John Aaron:

“Right after the spacecraft got into orbit the rules called for me to start powering it up and turn on the heaters to warm up the inside. I told Flight I didn’t want to do that because I realised something was really wrong. The power system wasn’t activating right and the temperatures were going up instead of down in the workshop.”

For ten days engineers worked to save the project before the Skylab 2 mission was launched on 25 May to fix the problems by means of EVA. Lindsay:

“Tally Ho! The Skylab. We got her in daylight at 1.5 miles, 29 feet per second.” It was 8 hours after another perfect Saturn 1B launch at 9 am EST, and Conrad could see the crippled laboratory above the bright Earth below. They did a fly‑around Skylab and sent video pictures of the damage back to Houston, confirming that the micrometeorite shield was gone and the single remaining solar panel was stuck down by what looked like a strap of aluminium.

They parked the Command Module by soft docking it to the laboratory, and while the ground crews studied their television pictures of the damage, the astronauts tucked into their first meal.

“Dinner’s going pretty good,” reported Conrad, “except that Paul found another one of those tree trunks in the asparagus. I had stewed tomatoes for lunch. It turned out even as goopy as they are, they were real simple to handle, and the same way with the turkey and gravy.”

After discussions with the ground they decided to do an EVA to try and prise the solar panel loose. Working from the Command Module hatch they tried to free the solar panel beam from the aluminium strap holding it down by cutting it.

Kerwin recalls, “Weitz was hanging out the side door with a shepherd’s crook in his hand – a ten foot pole with a hook in the end – trying to stick it under the opening in the solar panel to pry it up, while I had my arms around his legs to hold him in the Command Module. Pete was flying the spacecraft and every time Weitz would pull on the shepherd’s crook the two spacecraft would move towards each other and the jets would fire on the Skylab workshop and the jets would fire on the Command and Service Module and Pete would have to haul back on the stick to keep them from colliding – it was pretty spectacular.”

Weitz explains, “I tried to pry the beam up but it didn’t work because the aluminium strap was too firmly fixed. We had another fitting on the end of the pole which was a branch cutter. This thing is wrapped around your leg and comes up over your ankle to your knee on the inside and you have these scissors held parallel to your leg. These cutters didn’t work – they just weren’t beefy enough and I couldn’t get enough purchase on it to cut through the strap, so we had to give up.”

When they entered the night side they closed the hatch and tried to dock with Skylab again, but this time the soft dock latches refused to lock. Kerwin says, “The three soft dock latches which had worked perfectly the first time simply wouldn’t capture. Pete tried and he tried and he tried and he tried again – we went through the back‑up procedure and it looked like we had a spectacular failure here where we would have to come home because we couldn’t dock.

“We finally backed off a little bit and decided to try the last ditch third back‑up procedure that was in the checklist, which fortunately one of our trainers had shown us a few weeks before launch. ‘We have never looked at this back‑up procedure – why don’t we just go through it and show you where the wires are,’ he had said to us.

“This involved an IVA (Intravehicular Activity) so we had to get back into our suits, depressurise the spacecraft again, but this time we opened the tunnel hatch where the docking system was. We went up in there and cut a wire to bypass the soft dock system. We put the hatch back on but this time the deal was we were just going to force it in to where the main hard dock latches might work. In came Pete one more time, hosed on the fuel, pushed the switch to activate the twelve main latches and we counted one, two, three; we got to about seven and we heard this rat‑a‑tat sound which was all the twelve latches locking on one after the other – that was a very sweet sound – and we had a good hard dock. We had been up for about eighteen hours by then – we were kinda tired – so we had a snack and went right to bed.”

When Conrad, Weitz, and Kerwin awoke, the first task was to check the atmosphere in the laboratory for any deadly gases. Weitz says, “We had a sniffer – a glass cylinder with a rubber bulb on one end like a hygrometer they used to test batteries in the old days – with an adapter to go in the MDA hatch. We sniffed that and it didn’t show anything so we opened the hatch. In the MDA it was relatively cool, in the fifties (10°C) as I remember, but when we got in the airlock it was very hot. Pete and I said if it’s hot in there we’ll go in our skivvies, but then we soon found out why the people in central Africa wear a lot of clothes when they are in very hot conditions – we bundled up rather than took clothes off because of the heat. We made forays into the workshop for about ten or fifteen minutes until we felt we needed a break then we went back to the MDA to cool off for a while. Except for the temperature, everything looked as it should be.”

Kerwin remembers, “In the lab it was quite warm and it had a somewhat chemical smell – not bad – a sort of gasoline smell.” The temperature was 54°C, but the humidity was so low they were able keep working for up to five hours at a time.

The next item was the thermal shield. Conrad and Weitz carefully eased the $75,000 parasol developed by Kinzler and his gang through the scientific airlock and extended the struts until the sunshield was in place. Weitz says, “On day two we went to work putting up the parasol. It took most of the day. As I remember everything went according to plan but as it turned out all the four extendible booms didn’t extend, one of them did not, so the thing was not quite a rectangle, but we didn’t know that at the time.”

Conrad set the scene at the time. “The rod extension has gone easily enough. It’s pretty warm down here, so we are taking little heat breaks.” Almost immediately the temperature in the laboratory began to drop, eventually taking a week to stabilise at 21°C.

Weitz adds, “The next day things had cooled down a little so we started the activation procedures which meant moving a lot of stuff. A lot of items were bolted to the triangle floor.”

Now came the most difficult job – extending the remaining solar array. The solar panel beam was extended by a hydraulic piston. This beam was jammed by a strap from the micrometeorite shield lodged there during the launch phase. On the ground at the Marshall Space Flight Center astronauts Rusty Schweickart and Story Musgrave had developed and practiced the procedures to clear the beam on a mockup of the laboratory, complete with the strap, as seen on the television pictures sent by Conrad.

Fourteen days after the first docking, Conrad and Kerwin tackled the procedures developed by Rusty Schweickart. Working on the smooth tank‑like laboratory with no gravity, toe or handholds to steady them, the two astronauts set up the long‑handled cutter, like pruning shears, used in the first attempt. They had to wait and fly through an orbital night before they could try it out.

Kerwin recounts, “I had on my suit an extra six foot tether, just a rope, with hooks on both ends. Where we were there was an eyebolt so we hooked one end of the tether to a ring on the front of the suit, snaked it through the eyebolt and back up to the suit, hooked it again, adjusted it to the right length and I could stand up with my two feet planted one either side of that eyebolt and suddenly I was standing there as steady as you could get with a three‑point suspension. Once we had accomplished that, it was only a couple of minutes work to get the jaws in place. Pete had to help me a little with depth perception to get it exactly right – he said: ‘No… you passed it… come back, dammit… no… nowback…’

“So it went on and I pulled the rope just hard enough to tighten the jaws against the strap but not hard enough to cut it. That was very important, because Pete was now going to use that twenty five foot pole as a handrail. He went hand over hand down to the solar panel, trying to take care not to cut himself, and attached another rope to the cover of the solar panel.”

Conrad hooked one end of the rope to a vent module relief hole on the beam, and the other end was secured to an antenna support truss on the solar observatory.

Kerwin continued:

“First we tightened the jaws the rest of the way and cut the strap of aluminium. When we did that the panel came out another few inches and stopped.”

Conrad, inspecting the jaws, suddenly found himself tumbling out into space to be brought up with a jerk by his umbilical cord. “That shot me out into the boonies!” he chuckled. He looked back to see the solar panel was only extended about 20°.

Kerwin adds, “We knew that would happen – that’s what they told us at Houston – that the joint is very cold, it’s frozen, you’re going to have to break the friction. That was what the second rope was for, so now we disposed of the twenty five foot pole then the two of us worked our way under the remaining rope and stood up between the rope and the lab. That exerted just enough tension on the solar panel cover to break the friction. Suddenly – I want to say there was a cracking sound but of course there wasn’t because we couldn’t hear it – but there was this sudden release of tension in the rope and we both went flying ass over tea kettle into space. We hand over handed our way down to some structure, turned around to look, and there was the solar panel fully deployed, sticking out ninety degrees, and the panels were already starting to come out.”

At the other end of the radio link the flight controllers heard Conrad say, “Whoops, there she goes!” and within six hours the solar panel was functioning and sending 7,000 watts of power to the workshop, enough to ensure the missions could go ahead as planned.

The Skylab mission, the whole $2.6 billion project, was saved!

The crew agreed that the best form of relaxation, 237 mi. Tles above the earth, was just looking out of the windowheir favourite music to accompany weightless exercise was from the film 2001.

They found sleeping difficult, as astronaut Paul Weitz explained:

‘I tried for a day or two but I was not comfortable sleeping with what I perceived as hanging on a wall, even though it was zero G. I wanted to get a good night’s sleep. I didn’t wander that far. Each night I would take my bunk up into the upper part of the workshop and lay it out so it was towards the Command Module. Also those sleep compartments were small, and I preferred to have more space.”

It wasn’t always easy to get to sleep. As the laboratory swung around the world from day to night each 93 minutes the skin creaked and popped with the change in temperature. If the thrusters fired during the night to keep the laboratory’s attitude, they sounded like bursts of gunfire. If anyone got up he would wake the others.

The Skylab toilet was a hinged, contoured seat mounted on the wall – it was uncomfortable and awkward to use, but did work. The astronaut sat on the seat, fastened a belt across his lap, and used forced air drawn into a plastic bag to collect the faecal matter. The shower was a cylindrical cloth enclosure fed with water from a preheated pressurised portable bottle. With only 2,722 kilograms of water on board, bathing showers were rationed to 2.8 litres of water per shower per week. The liquid soap and water were carefully measured before the mission and rationed out – no luxurious long hot showers if you were feeling a bit seedy! Weitz was first to try the shower. “It took a fair amount longer to use than you might expect – 15 minutes of shower and 45 minutes of cleaning up – but you came out smelling good!” so it wasn’t really a success. They found it was easier to rub down with wash cloths.

Weitz added: “Zero‑G is both good and bad. It’s a great environment for moving around, to play in, and to work in, but it’s not so good when it comes to things like going to the bathroom or brushing your teeth and you like to spit the toothpaste out into the sink and watch it go down the tube, instead of having to spit it out into a used towel, or something like that. The bathroom became the barber shop every few weeks, the barbers sucking the cropped hair away with little vacuum cleaners.”

The Skylab 3 mission was from 28 July until 25 September 1973, a duration of 59 days. The crew of Al Bean, Owen Garriott and Jack Lousma had some problems with the thrusters on their Service Module. Houston considered sending a rescue mission with a module modified to fit five astronauts, but the readings improved and the problem was not as serious as it had seemed.

The crew enjoyed sun watching. Their watches at the solar console were the only form of privacy they had, but they could watch the sun any time they wanted. There was constant solar activity – filaments streaking up, flares, enormous bubbles forming and bursting.

When the Skylab 4 mission arrived they found the station was already occupied – the previous mission had left three stuffed flightsuits behind! William Pogue, Edward Gibson and Gerald Carr would stay for 84 days. Gibson:

“It was a shame to read with all that was going on outside. I would read a little when Skylab was over water, but when we reached the shore I would put the book down, and look at the continent below.

“Carr would sneak off to the Command Module, the most private place, turn the speaker off, and get some reading done that way.”

On 21 January 1974 they made the first observation of a solar flare. The crew protested at their heavy workload and refused to work as hard as the crew of Skylab 2. Lindsay:

On February 9, after some experiments such as erasing a computer memory and reloading it, Skylab was put in a vertical attitude with the docking hatch looking away from Earth in the hope this would prolong its life, and at 2 pm the last command was sent to switch the telemetry off. By this time the laboratory was showing signs of wear and tear. The gleaming gold, white, and silver paint on the outside was becoming tarnished, the white paint had browned and the gold had baked and blackened. Despite the initial setbacks, Skylab had met, or exceeded, every requirement placed upon it.

Originally planned for 140 days, Skylab was manned for 171 days, 13 hours, and 14 minutes, taking the crews around the Earth 2,476times, a distance of 113,455,650 kilometres. This was a lot more than all the previous American manned spaceflights put together, which totalled 146 days, 21 hours, 36 minutes, and 8 seconds. 565 hours of Sun observations were planned, 755 were actually spent; 701 hours of medical experiments grew to 822 hours; and instead of only 60 Earth observation passes, they eventually completed 90.