Outposts on the Frontier: A Fifty-Year History of Space Stations (Outward Odyssey: A People's History of Spaceflight)

by Jay Chladek

  Going Dry

  By late 1968 the OWS looked very much like the station that would eventually become known as Skylab. It was an S-IVB rocket stage designed to power itself into Earth orbit with a single J-2 engine. Strapped to the sides of the stage were a pair of large solar arrays. Once the OWS reached orbit, the arrays would unfurl to generate the electricity needed. Mounted at the front of the S-IVB was a large airlock with multiple docking ports. An Apollo CSM would dock at the front port, and a lunar module reconfigured as an ATM would dock at one of the radial ports. The ATM’s heavily modified LM descent stage had four solar arrays arranged like a Dutch windmill. These arrays would generate power for the OWS when docked and for the LM when the ATM flew free (albeit in a tethered state). It all looked good on paper, but how would things shake out in testing?

  16. A 1968 drawing of the S-IVB wet workshop with lunar module–based Apollo Telescope Mount (the Skylab that almost was). Courtesy NASA.

  In 1968 von Braun began work on a secret project at Marshall in support of the OWS. This was a neutral buoyancy tank (NBT). In this deep fresh-water pool, astronauts would be weighed down so that they would neither float nor sink, and the experience would be similar to weightlessness. Unlike the ocean-based facility used by the MOL, the space suits worn would be pressurized with air. Although water is more resistant to movement than space, the laws of physics in the tank still apply. Every action has an equal and opposite reaction. So if an astronaut is not anchored properly and uses a wrench to turn a bolt, the wrench will turn him the other direction.

  Building this facility was a violation of proper expenditure procedures within NASA, but von Braun did it anyway since he knew that if the wet lab proposal were going to work, his engineers had to test the concepts in a practical matter. George Mueller was made aware of the tank on a visit to Huntsville in early 1969, and he didn’t think it was a bad idea at all. Thanks to the NBT, engineers found that refitting the S-IVB from a rocket stage into a workshop in space was turning out to be a lot harder than originally anticipated. Von Braun and his managers felt that a can-do attitude would make the wet lab work. But when they began their first NBT runs, they ran into several difficulties.

  After going into the NBT himself with von Braun, to investigate and experience the problems firsthand, George Mueller was no longer a champion of the wet lab concept. He didn’t abandon the idea entirely, and neither did von Braun, as both men still believed that it could be made to work. But specialized procedures, tools, and techniques take time and money to develop, and AAP didn’t have very much of either resource.

  So Mueller began calling for a dry lab approach. Technically, the dry lab would be very much the same as the wet lab. But it would be fully outfitted as a space laboratory on the ground and furnished with all the provisions it needed before it flew. When a dry lab was launched, it would be ready to begin scientific work once the first crew arrived. There was just one problem with this approach. Part of the reason why so much effort was put into the wet lab was because the only rocket booster available to launch it was the Saturn IB. The wet lab needed to act as a rocket stage since the Saturn IB’s first stage alone was not powerful enough to get a fully furnished lab into orbit.

  Logically, the best rocket for lofting a dry lab would be the Saturn V, but all the Saturn Vs were spoken for. Since it was not in the budget, another Saturn V could not be built either. But even with this setback, efforts were stated to alter the OWS design into a dry lab at both the NASA center and contractor levels, just in case a Saturn V were made available. The development of a dry workshop would also alter the ATM. If a Saturn V were available to launch a dry lab, the ATM could be integrated into the OWS completely, as one spacecraft, since the Saturn V had plenty of excess lifting capacity to handle both assemblies.

  In July 1969 the Apollo 11 mission successfully landed on the moon. Since the first lunar landing was a top priority, NASA had been holding many of its resources in reserve until that goal was achieved. With the lunar-landing goal met, some of those resources could be used for other things. After Apollo 11’s successful flight, NASA transferred one Saturn V rocket over to AAP to fly the OWS.

  The decision had been a few months in the making already when it was publicly announced. James Webb retired from NASA at the end of 1968. Webb’s deputy, Thomas Paine, took his place in the head office. Paine was much more receptive to the AAP project, and he also recognized that NASA needed a post-lunar-mission goal. So work secretly began behind the scenes to put a Saturn V at AAP’s disposal. As a result of the Saturn V transfer, the weight constraints and necessity for a wet lab were no longer obstacles. The OWS would fly dry.

  AAP Becomes Skylab

  The official name change from AAP to Skylab occurred in early 1970. There had been dissatisfaction among many in NASA with the AAP acronym, as it had become the butt of jokes with terms like “Almost a Program” and “Apples, Apricots, and Pears.” NASA administrator Thomas Paine formed a committee for name suggestions, as he felt a good name could score some public relations points and spark general interest in the program. Many names were considered, but eventually NASA selected the name Skylab, submitted by Lt. Col. Donald Steelman, a U.S. Air Force officer on duty with NASA.

  Some changes were afoot on the management side, as George Mueller left NASA in late 1969 to take a job with General Dynamics. Dale D. Myers from North American Aviation (soon to become North American Rockwell) joined NASA and took over management of AAP when Mueller left. Wernher von Braun was also transferred away from MSFC to Washington DC to become NASA deputy associate administrator for planning. Von Braun’s time in Washington was short, retiring from NASA in 1972 before dying of cancer in 1977 at age sixty-five.

  In the astronaut office, Apollo 7 veteran Walter Cunningham became chief of the Skylab branch Flight Crew Operations Directorate. A lot of people credit Cunningham’s input with helping to turn Skylab from an amalgamation of experiment proposals and ideas into a cohesive set of hardware that could do the job once it arrived on orbit. Other astronauts had held this particular post during the early days of AAP, but the prevailing attitude among the astronaut corps at the time was that the OWS was so far down the line that not a lot of work should be focused on it, when the lunar program was the big show.

  In his autobiography, The All-American Boys, Walt Cunningham considers his work on Skylab for the two years he was part of the program to be his real contribution to manned spaceflight. Cunningham had already been known as a good manager, and he had worked closely with scientists while working at the RAND Corporation in the early 1960s. Because of this experience, Cunningham seemed to provide the correct skill set that Skylab needed when it transitioned from a drawing board program to hardware.

  Cunningham was aided in his tasks by Story Musgrave, who was selected in 1967 as part of a second class of scientist-astronauts. The group of eleven astronauts again had broad scientific backgrounds with only one or two having any skills that might directly contribute to the Apollo lunar program. NASA had plenty of astronauts already. So the second group called themselves, in a humorously ironic fashion, the XS-11, or “excess eleven” as it became more commonly known. The glut of scientists didn’t last long, though. By the end of 1969, five members from each scientist-astronaut class had either been asked to leave or resigned while deciding that the astronaut program was not their cup of tea. That left only twelve, and Cunningham had a few of them at his disposal in addition to Musgrave. Other scientist-astronauts such as Owen Garriott and Joe Kerwin were also involved heavily in Skylab development, and both men would get flight assignments as Skylab crewmembers.

  Cunningham also got some additional manpower when the air force’s MOL project was canceled. He inherited the seven MOL astronauts who were hired by NASA and put them to work where their skills and knowledge of similar systems were invaluable. The scientist-astronauts became the direct interface with the scientists hoping to fly their experiments on the workshop, while the MOL astronauts wo
uld help with configuration and hardware design. These efforts helped to get the work of two NASA centers and five major hardware contractors coordinated properly.

  Skylab was initially assigned a launch date in December 1972, and efforts ultimately began moving toward that goal as the hardware began to come together. But the date would slip due to further budget cuts and a lack of enthusiasm by the Nixon administration. Administrator Paine would eventually resign from NASA in mid-1970 as his own goals for the agency didn’t match the White House’s. When further budget cuts came down, acting administrator George Low took up the job in Paine’s place until James Fletcher was appointed NASA administrator later that same year.

  The latest budget casualties were Apollo 20 and the Saturn V production line. There also wasn’t enough money to fly Apollo 18 and 19 along with Skylab either. Low figured that of the programs under the budget ax, Skylab at that time had the potential of returning more useful science than a couple of more missions to the moon. So the hard decision was made to cut the lunar missions after Apollo 17 and keep Skylab on track. Having two unused Saturn Vs from the canceled lunar missions might have allowed for a second OWS to fly, but funding to fly a second Skylab was never made available. A second Skylab workshop was built, but it was kept as an engineering backup only and never flown. It eventually became an exhibit at the Smithsonian’s National Air and Space Museum.

  Anatomy of Skylab’s Orbital Workshop

  If the twenty-ton Salyut was considered big, Skylab was truly massive, as the space station weighed nearly one hundred tons when it finally flew. The largest structure was made up of the converted S-IVB, which was slightly longer than a contemporary tractor-trailer truck. The exterior of the S-IVB was covered with a micrometeoroid shield. This shield would serve a secondary role in passively controlling the thermal temperature of the station’s interior. Primary power for the station would come from a large pair of solar arrays located on each side of the station, which would fold out once the station reached orbit.

  At the front of the S-IVB was the airlock section, which contained two Apollo docking ports and a separate airlock for space walks. Located on top of the docking adaptor and airlock section was the ATM, housing the instruments needed for observation of the sun and the section’s four dedicated solar arrays. Many of the experiments located in the ATM used film, so periodically the astronauts would be required to perform space walks to retrieve film canisters and replace them with fresh ones.

  Attitude control of Skylab would come from a set of nitrogen-powered thrusters for fast movements and control-moment gyros in the ATM for station keeping and slower orientation changes. The control-moment gyros were designed along a similar principle to the gyrodynes used in Salyut but were larger in size. For most maneuvers, only the control-moment gyros would be used, in order to help save thruster fuel.

  17. Illustration of Skylab. Courtesy NASA.

  Like the Apollo spacecraft, Skylab would be pressurized to 5 psi in orbit. But there were medical concerns about breathing pure oxygen over a long duration, so a change was made to a two-gas system of 72 percent oxygen and 28 percent nitrogen. The internal pressure was kept low, since the Apollo spacecraft itself couldn’t handle internal pressures higher than 8 psi and since a higher pressure would require astronauts to prebreathe pure oxygen to flush nitrogen from their blood prior to EVAs in order to help prevent the bends. Since the internal atmosphere in the lab was still only one-third of the pressure at sea level on Earth, sound didn’t carry very well over long distances. So thirteen intercom system panels installed in various areas of the lab became an excellent investment once the station became operational.

  Astronauts would launch into orbit on a modified Apollo CSM setup for long-duration missions. To do this, engineers removed some of the craft’s fuel cells and associated cryogenic tanks, replacing them with storage batteries. Once docked, the remaining fuel-cell stacks would deliver their power to the workshop until their consumables were used up. A storage tank was installed in the service module to collect the waste water from the fuel cells. This was done so that water vapor from venting would not contaminate the delicate instruments of the workshop. Before coming home, the CSM would get its batteries topped off by Skylab’s power supply.

  The supply of fuel to the service module’s main engine was reduced since it was only intended for use in the deorbit burn, while the fuel supply for the spacecraft’s reaction control system was almost doubled for rendezvous and docking maneuvers. One side of the command module was painted white to help with thermal control, since that side of the spacecraft would be constantly pointed toward the sun while docked with Skylab.

  The CSM would dock with the workshop on a docking port in line with the station’s longitudinal axis. A second docking port was provided on the bottom of the airlock module. This port would be used in an emergency and could accommodate a second CSM if needed. If a problem kept a docked CSM from returning home safely, NASA had a dedicated rescue CSM at its disposal. Two astronauts would fly the ship into orbit to retrieve the three-man crew on the station. The five astronauts would then ride home with three seated normally while the other two sat in couches in the spacecraft’s lower equipment bay.

  Skylab’s docking port and airlock section also housed the control system for the ATM. Seated at a workstation, an astronaut could steer Skylab to aim its telescopes as needed at either the sun or other targets of opportunity. The airlock located in the “floor” of the docking compartment meant that the entire station didn’t have to be depressurized during EVAs, but usually the third crewmember would stand watch inside the docked CSM in case an emergency arose.

  For EVAs, Skylab astronauts wore slightly modified versions of the lunar suits designed for the Apollo program. But rather than using a self-contained, portable life-support system backpack, the Skylab suits would get their oxygen supply from a tether to the lab via the airlock. A safety lifeline tether was also provided. Breathing oxygen would be supplied through a control unit located on the astronaut’s waist, and a secondary oxygen supply tank would be located on the astronaut’s right hip.

  The primary habitable volume of the station was in the S-IVB stage. The “floor” of the workshop was oriented vertically, while the airlock compartment’s “floor” was oriented relative to the longitudinal axis of the station. The OWS was divided into two main levels. The bottom-most level, known as the crew quarters deck, contained the living quarters for the astronauts. Each private room contained a sleeping bunk and blankets strapped to one wall and storage lockers for each crewmember’s personal belongings along with a tape player. Music from each tape player could be routed to other parts of the station via the intercom system. Since Skylab had no washing machine, the supplied clothing and towels for each crewmember were thrown away once they got too dirty.

  A ward room with galley table was provided next to a window with a view of Earth. The ward room housed the food freezer along with other supplies. The central galley table had both hot and cold water hoses for rehydration of drinks. To save valuable space on the Apollo CSMs, nearly all of Skylab’s food supply was launched into orbit with the workshop itself.

  A fully enclosed bathroom with a wall-mounted vacuum toilet was also housed on this level. Solid and liquid waste were collected in separate bags. Each bag of fecal material was dehydrated and baked in special dryer ovens to remove moisture and help maximize storage space. Only small samples of urine were collected for analysis, and these samples were frozen for storage and the return trip. The remaining urine was collected in a disposable containment bag that was changed daily and discarded with the rest of the trash. A personal hygiene station was located next to the toilet, and here astronauts could use fresh water to wash their hands as if using a sink on Earth.

  The center of the first floor housed a trash receptacle opening. Astronauts would place trash inside the container, close the inner hatch, and open the outer hatch to suck the trash into the S-IVB’s empty liquid oxygen tank. Th
e trash would remain there until the station was deorbited. The first level also included a shower in one corner. Crewmembers would enter the shower, pull the flexible curtain up to seal it with a ring on the ceiling, and spray water on themselves with a hose equipped with a spray fixture. A vacuum hose was used to remove the excess water droplets.

  Half of the first level also housed much of the biomedical equipment used during the mission, including a negative-pressure device and the spinning chair used to test vestibular function. Control panels for electrical power and internal temperature were also located on the first level.

  The second level was separated from the first by an open-structure floor webbing with a triangular pattern. This was a throwback to the wet lab design, as the webbing was designed not to impede the flow of liquid hydrogen while the S-IVB was operating as a fuel tank. Astronauts could get from the first to the second level of the lab through a central opening. As a side benefit, engineers designed a triangular foot restraint that could grip into the floor to anchor the astronauts if needed.

  The second level housed some of the exercise equipment, such as a bicycle ergometer, a table for weight exercise, and a tape player for entertainment. It was also equipped with additional storage lockers. The twenty-foot-high ceiling for the second level was the inside top of the LHX tank, and the large volume provided by this twenty-one-by-twenty-foot area was wide open enough for all three astronauts to float around freely without bumping into anything. A complete ring of storage lockers were located along the wall midway up, and these became a zero-g running track for Owen Garriott. Other astronauts used them as gymnastics mats.