by Jay Chladek
Astronauts found that they could locomote their bodies to a wall as needed and that air currents from the station’s ventilation system would eventually move a crewmember to a wall if one tried to remain stationary in the middle of this cavernous area. So a firehouse pole provided by Skylab’s designers in the core of the station was usually stowed after a few days, once the crew got the hang of moving around in zero gravity.
The Science of Skylab
Since Skylab was the first dedicated mission of long-term manned spaceflight where the crew didn’t have to spend most of its time actively flying the vehicle, science gathering was the priority. But the astronauts would not just be making observations and collecting data with their instruments; they would be experimental subjects as well. Skylab had an arsenal of biomedical equipment at its disposal.
Exercise would be a big key to fighting the effects of weightlessness; for that, astronauts had a few devices at their disposal. An isokinetic dynamometer weight table was provided. It was designed to provide simulated weight using electrical resistance. For cardiovascular exercise, a bicycle ergometer was used; scientists could monitor how well an astronaut performed by the amount of electrical current he generated from pedaling.
After the first two crews came home, it was determined that a treadmill might be more effective than the bicycle ergometer due to balance issues that cropped up during recovery. So a low-tech treadmill, designed by astronaut Bob Thornton and nicknamed Thornton’s Revenge, was flown with the third crew. It was simply a sheet of slick Teflon material that the crewmember was strapped to in a standing position with a pair of elastic cords that gave a simulated weight force. Wearing socks, the astronaut could run in place on the sheet. It provided body loads similar to a regular treadmill, without moving parts.
The spinning chair tested vestibular function by spinning a person in one place while he moved his head. This was done to see if the activity could bring about an onset of space adaptation syndrome, a condition that tends to incapacitate astronauts with dizziness and nausea as their inner ear and eyes have a hard time adapting to the new environment. There is no way to predict with 100 percent certainty whether somebody will be prone to such a condition, and a lot of effort was expended during the Skylab program to try to understand it better.
Food was an important part of the Skylab mission since the astronauts’ caloric and nutritional intakes would be monitored closely. The food preparations for Skylab were and still are the most elaborate of any space mission to date. Space missions flown to this point made do with camping-style food and dehydrated pouches that had to be reconstituted with water. But while the astronauts considered this form of cuisine tolerable for short-duration trips, there were concerns of low morale if a crew had to eat the same things on longer missions.
On Skylab the meal choices were expanded with canned foods that didn’t require rehydration. Even cold-stored foods, such as ice cream and canned fruits, were available thanks to Skylab’s freezer. The only items that needed rehydrating were the drinks. Each astronaut had a food tray with slots for warming some of the food cans, and these were attached to the galley table during mealtimes. Each astronaut had a set of magnetic eating utensils that could be anchored to the food tray when not in use. Astronauts would regularly rotate who performed the kitchen duty to prepare the food at mealtimes.
Except for the small identification labels, most of the cans looked almost identical to one another. This caused a slight problem on the third manned Skylab mission, as astronaut Bill Pogue accidentally heated up a can of ice cream intended for crewmate Ed Gibson. But rather than getting mad, Gibson simply put the can back into the freezer for a bit. When he pulled it back out, the ice cream had refrozen into a hollow ball. Ed then stuck some strawberries in the middle and enjoyed the first ice-cream sundae in space.
The meals selected for Skylab were a balancing act between nutrition, scientific data requirements, and the enjoyment of the crew. Each nutrient in the food had to be accounted for to determine what substances were being excreted in an individual crewmember’s urine and feces. To establish a baseline of data both before and after the flight, astronauts began their special diets a week or two before launch and continued a week after returning.
Blood and tissue samples would be taken on orbit by each of the crewmembers, so even the astronauts without a medical background had to be trained in drawing blood from one another. Some blood studies could take place on orbit, but for the most part, the samples were preserved for the trip home. The astronauts weren’t the only subjects of life science studies; pocket mice and fruit flies were also flown to the station for the crew to monitor their development. Two spiders were also flown and monitored to determine if development of spiderwebs would be different in a zero-g environment than on the ground.
The spiders were flown as one of the first experiments suggested by school students. Other student experiments were more sophisticated, and some were in areas that professional scientists hadn’t even thought of before. Skylab was the beginning of many fruitful years of student-suggested scientific experiments flying in space. That relationship continued through the shuttle era, and student experiments also take place on the International Space Station (ISS) today.
One of the most important elements of Skylab’s science gathering was the ATM. What started as little more than a retrofitted LM had become a sophisticated solar observatory that mounted eight different telescopes in a single housing. This arrangement would permit the collection of data from the visible-light to the ultraviolet spectrum and on X-ray wavelengths. Some instruments on the ATM were designed to study the sun as a whole, while others were designed to focus on specific regions or targets of opportunity. From the ATM control panel in the airlock module, an astronaut could see activity on the sun with up to four television monitors and focus on specific regions to collect data, depending on what feature was being studied. The entire workstation for the ATM looked about as complicated as a flight engineer panel on an old commercial jet airliner. In addition to the equipment used to monitor the cameras, it also contained controls for steering the station.
Instrumentation mounted in the ATM included two hydrogen-alpha telescopes designed to record light wavelengths emitted by hydrogen atoms in various forms. These telescopes could see things that were not observable in other light wavelengths. Although the sun is essentially a big ball of gas, it still has surface features; hydrogen-alpha filters produce the distinct deep-yellow images of the sun where these features are visible.
A white-light coronagraph was also provided. The corona is a cloud of gases around the sun that normally can’t be observed unless light from the sun itself is blocked. A solar eclipse can also occlude the sun’s disk to allow a corona to be seen, but only for short periods. While solar telescopes can use an occlusion disk to block the sun, the atmosphere can distort the effectiveness of the disk. Today, many ground-based telescopes can counteract atmospheric distortion with computers and special lenses to view the sun’s corona, but in the early 1970s such technology was not yet available. Skylab would allow for the first long-term studies of the sun’s corona.
Other ATM instruments included an extreme ultraviolet spectrograph and spectroheliograph in addition to other equipment that could detect ultraviolet wavelengths. An X-ray spectrograph and camera were also carried. Ultraviolet light and X-rays, which can be harmful to living organisms, are mostly filtered out by the atmosphere. Spectrographs are used in astronomy to help determine the chemical composition of stars and other heavenly bodies. Different atomic and molecular compounds produce different colors when their visible-light wavelengths are separated and analyzed. Since the sun is so hot and bright, it obscures almost everything in the visible-light wavelength. But ultraviolet light and X-rays can be analyzed to collect the same data. The spectrograph was designed to analyze parts of the sun’s surface, while the spectroheliograph was designed to do the same thing to features found in the sun’s chromosphere, a thin atmos
pheric region of the sun near its surface.
For Earth-observation studies, additional spectrographs, radiometers, scanners, and photography equipment were mounted in the bottom of the Skylab docking module near the second docking port. Scientific data collection was the key here as opposed to photographing specific points on the ground like MOL and Almaz. But astronauts also had access to handheld photographic, television, and movie cameras.
Getting Hardware Ready for Flight
It was decided that a ground-based dress rehearsal of sorts should be carried out to help shake out any problems, since much of the equipment would be flying in space for the first time. So engineers devised a test called the Skylab Medical Experiments Altitude Test, or SMEAT. The test essentially involved locking three people up in a sealed environment for fifty-six days to conduct a simulated mission. Like an actual Skylab mission, the atmosphere in the SMEAT environment would be pressurized to 5 psi. The astronauts would evaluate the equipment, the mission plan, the food, and the test procedures to uncover any unforeseen problems. Additionally, the medical data collected would be used as a baseline comparison with the Skylab missions themselves.
Three Skylab support astronauts were selected to take part in SMEAT. The first two were MOL veterans Bob Crippen and Karol “Bo” Bobko. Dr. William Thornton, an XS-11 class member with experience in engineering and as a U.S. Air Force flight surgeon, was the third member. As per Skylab protocol, they would begin their preflight food diets a couple of weeks before “launch” and conduct a battery of medical tests on one another. The SMEAT experiment was conducted in the late summer of 1972.
The crewmembers did their jobs very well and uncovered issues in most everything tested. William Thornton became somewhat legendary during SMEAT. His physical build and extremely good shape made him perfect for uncovering problems with the bicycle ergometer, as he practically tested it to destruction, according to some accounts. Thornton’s medical background also helped him to lobby the medical specialists that their one-size-fits-all approach to astronaut diets wasn’t exactly a good idea, as people with different metabolisms can require a different caloric intake from one another. Thornton also proved that the one-size-fits-all urine bags didn’t do the job either, as his urine output typically would exceed the bag’s capacity. As far as dress rehearsals go, SMEAT was a valuable experience for almost all involved, and many credit its results as the reason why no major issues cropped up with Skylab’s biomedical equipment during its operational use.
At the Kennedy Space Center (KSC), rocket stages and hardware for Skylab began to come together in the vehicle assembly building alongside those for Apollo 17, as the NASA facility was the busiest it had been since 1968–69. Accommodations for Skylab’s Saturn IB boosters would mean that changes were in store for one of the launchpads.
During Apollo, Saturn IBs had flown from launchpads 34 and 37 of the Cape Canaveral Air Force Station. After Apollo 7’s successful launch, both pads were decommissioned, and useable equipment was repurposed for use at KSC’s Launch Complex 39. Since the Saturn V was a much taller booster than the Saturn IB, the launch umbilical towers designed for it could not be used with the smaller rocket without modifications. The solution came in the form of a stilt pad structure built on the base of the launch tower so that the Apollo CSM and the S-IVB rocket stage of a Saturn IB would sit at the same height as a Saturn V. This stilt pad unofficially became known as the “milk stool.”
The Saturn V pad used for Skylab was modified to accommodate testing and checkout of the lab prior to launch. Some supplies could only be loaded relatively late in the countdown, so a side door in the lab itself allowed for access at the pad. And modifications were made to the support structures to allow technicians to carry out the needed work inside. The side door was only used for launch preparations.
The Skylab crews were selected in 1971. The first crew was commanded by Charles “Pete” Conrad, a Gemini and Apollo veteran. Joining him were two rookies: scientist-astronaut Joe Kerwin, MD, and pilot Paul Weitz. The second Skylab crew consisted of veteran Alan Bean, rookie scientist-astronaut Owen Garriott, and rookie pilot Jack Lousma. The third crew was made up entirely of space rookies. Commanding the mission would be Gerald P. Carr. Joining him were scientist-astronaut Edward Gibson and pilot-astronaut William Pogue.
The crews were selected a little differently from crews of previous programs. During Apollo, chief astronaut Deke Slayton usually had the final say in crew selections, and he tended to favor test pilots instead of scientists. For Skylab, appeals were made to have two scientists fly on each mission, but in the end, it came down to a crew selection of only one scientist per crew. This meant that several qualified scientist-astronauts would not get to fly until the space shuttle began operations a decade later.
Launch Day
The first stacked Skylab Saturn IB arrived at launchpad 39A in late February. On 16 April 1973, the Skylab workshop’s Saturn V booster on its mobile launch platform began its long trek along the crawler way to pad 39B. Seeing two rockets stacked on both pads made for quite a sight at KSC. Two firing rooms at KSC’s Launch Control Center would control the counts for both rockets simultaneously. The Skylab workshop would enter orbit first. If all went well with deployment of the workshop, the first Skylab crew would launch the next day to dock with the laboratory and set up operations. Pete Conrad’s crew began their pre-mission diets and spent a couple of weeks in medical quarantine in anticipation of their mission. Everything seemed ready.
As with the Apollo flights, a crowd of spectators gathered at KSC to watch Skylab get off the ground. The usual VIPs were invited to the launch, but Pete Conrad and his all-navy crew also extended invitations to the 591 U.S. military POWs from the Vietnam War who had recently been freed from North Vietnam’s Hanoi Hilton (some as recently as April 1973). Most were combat pilots, and some of these men had been held in captivity since the Vietnam War had begun. The POWs who were captured before July 1969 were not made aware that the United States landed a man on the moon until five months after it had happened.
Most of the astronauts had friends who flew combat over Vietnam. Conrad and his crew did not want to let the sacrifice of the POWs go forgotten or unrewarded. Among the former POWs who took up the invitation was air force colonel James Lamar, who was captured in May 1966 after bailing out of his heavily damaged F-105 Thunderchief. He watched the launch from ABC television’s press facility at the cape.
On 14 May 1973 at 13:30 Houston time, the last operational Saturn V lifted off from the pad and rose into the cloudy Florida sky. Overcast conditions meant that spectators and cameras lost sight of the vehicle about one minute into the flight as it passed through a layer of clouds. Nobody was able to view what happened next, but the characteristic Saturn V rumble could once again be heard many miles away. After seeing the launch, Colonel Lamar was asked what he thought of the experience, and he replied, “That has got to be the most awe-inspiring sight I have seen in my life. That is something. Tremendous!”
All indications showed that the Saturn was performing brilliantly, and most of the data coming back from Skylab indicated the same. But in mission control at the recently renamed Johnson Space Center (JSC) in Houston, there was an indicator light showing that Skylab’s micrometeoroid shield had deployed a little over a minute into the flight. Flight controllers dismissed it as an erroneous reading, because otherwise the booster and the lab were following their preprogrammed course and performing well. Ten minutes after liftoff, Skylab was in orbit.
Where EGILs Dare
The Skylab controllers sent a series of commands to activate the station and deploy its arrays, as the vehicle passed within range of the tracking stations and communications aircraft on the first orbit. Data coming back indicated that one solar array was not giving power at all, as if it were missing; the second one was only giving a trickle of power, as though it were jammed partially shut. Even worse, the temperature inside the lab was slowly climbing past its nominal levels.
Analysis quickly determined that Skylab had indeed lost its micrometeoroid shield and that one solar array was likely gone as well. The shield also doubled as a thermal cover for the workshop. When the station reached orbit, the shield was designed to spring open like a larger tube held away from the surface of the OWS with a series of standoffs to keep it constantly shaded. But without the shield, the sun’s rays would bake the workshop’s structure and cook the insides. Even if the interior wasn’t made totally uninhabitable, increased temperatures could degrade battery life, cause interior padding to off-gas toxic fumes, and potentially cause food to spoil. Without help soon, the Skylab mission was in danger of ending before a crew could occupy the station. The launch of the first crew, planned for the next day, was postponed indefinitely while engineers discussed both short- and long-term solutions.
For Skylab, the Apollo EECOM (Electrical, Environmental, and Consumables Manager) designation had been replaced with EGIL (Electrical, General, Instrumentation, and Life Support). Essentially, both jobs performed the same function, as the EECOM and EGIL were responsible for monitoring the items that keep equipment running and astronauts alive. But the EECOM would perform that job for the CSM, while EGIL would do it for the lab itself. Many of the Skylab EGILs were former Apollo EECOMs.
The quick fix for the temperature problem came from EGIL flight controller John Aaron. Aaron was already a legend at mission control for his quick thinking at critical times on several Apollo missions. To cool the lab’s internal temperature, Aaron instructed the guidance flight controller to pitch Skylab down a bit, rotating the workshop’s exposed surface partially out of the path of sunlight. Aaron would then monitor the power output of the ATM solar arrays to see if the lab had enough electrical power for its batteries. It was a highly unorthodox procedure and went against Mission Control protocol. But the flight director allowed it, and finally Skylab stabilized in an attitude that would keep the internal temperature from climbing too high. It would buy time for engineers to come up with more-permanent solutions.
