The month of May 1973 quickly turned from one of euphoria into, potentially, one of the darkest in NASA’s history. After closing out its Apollo lunar landing programme in spectacular style, the space agency turned to the launch of the Skylab orbital station … a gigantic workshop which would support three crews of astronauts for up to three months at a time. Skylab would seize the long-duration experience crown from the Soviet Union and the station’s first crew—Pete Conrad, Joe Kerwin, and Paul Weitz—were destined to spend a record-breaking 28 days in space. On 14 May, they watched in awe as Skylab rose to orbit and looked forward to their own launch, early the following day. Those plans ground to an unfortunate halt when Skylab encountered its first difficulties: at some stage during ascent, the micrometeoroid shield and one of two power-producing solar arrays had somehow failed, causing the station to overheat and placing the entire mission in mortal danger.
The launch of Conrad and his men was rescheduled for no earlier than the 20th, as engineers dug in with the details to save Skylab. One saving grace was that not all of the station’s exterior required protection from the onslaught of the Sun and a makeshift “shade” would not necessarily need to be tied down or composed of strong or rigid material. Proposals included spray paints, inflatable balloons, and wallpapers to window curtains and extendable metal panels, but at length ten options were short-listed for inspection. All had to be compact and lightweight, sufficient to fit inside the cabin of Conrad’s Apollo command module for the ride into orbit. At length, three final options for a protective sunshade were considered: one to be extended across Skylab’s exposed hull by means of a long pole, another deployed from the command module’s hatch, whilst station-keeping, or a third which would be deployed through the station’s solar-facing scientific airlock.
Of these, the second was the least complex, although it meant that Conrad would be forced to hold the Apollo spacecraft in position, alongside Skylab, whilst Kerwin and Weitz opened the hatch to install the sunshade. As for the other choices, the first option meant extensive EVA training and the third meant building something compact enough to fit through a small aperture, then unfurling to cover an area of several square metres. Although they were happy with the second option, Conrad’s crew had done enough EVA training to feel confident about the first option, and even the third option was “doable,” because it permitted them to work from the pressurised—but very hot—safety of Skylab itself. However, no one knew if the scientific airlock was clogged with debris, so the third option was ranked last and teams from the Johnson Space Center (JSC) focused on Option 2 and teams from the Marshall Space Flight Center (MSFC) explored Option 1.
In the JSC group’s plan, Paul Weitz would perform a stand-up EVA (“SEVA”) in the command module’s open hatch and attach the sunshade in two places along Skylab’s aft section. Conrad would then manoeuvre his ship to the forward end of the station, deploying the sunshade in the process, and Weitz would finally make a third attachment at the Apollo Telescope Mount (ATM). Nicknamed the “SEVA Sail,” the development of the sunshade was complex: for several solid days, seamstresses stitched the orange material, parachute packers folded it for deployment, engineers attended to its fasteners … and a steady stream of public tours gaped at it from a mezzanine gallery. As for the MSFC group, their plan revolved around an EVA from the ATM itself. Their sunshade looked very much like an oversized window blind, and its design was finished by the evening of 15 May. Joe Kerwin and the backup commander for the mission, Rusty Schweickart, participated in extensive underwater EVA trials.
“We had to answer certain very basic questions,” Schweickart later told the NASA oral historian. “Could we get physically around to where we had to be? Could we see certain things? These were questions which you couldn’t answer just looking at drawings. We had to get into the water, get on the real vehicle, and see whether certain things could be done.” Schweickart and Kerwin also verified the usefulness of hand-holds and foot restraints and identified any sharp edges upon which their suits could snag or tear.
During their time underwater, the two men evaluated the two sunshades and were able to determine the practicalities of what a spacewalker could physically see, taking into account the restricted field of view of their helmets. A debriefing was then held with the prime crew and 75 engineers, all clad in blue face masks to uphold pre-flight quarantine rules. “One by one,” recalled Schweickart of the two-hour-plus session, “we eliminated things and by about midnight … we basically had the outlines of what we were going to do.” The MSFC sunshade needed further work, and they eventually produced a configuration of two 14 m poles, to be “cantilevered” from the ATM. The poles were assembled from a dozen small sections, allowing them to fit inside the command module, with a rope running along their length, through a series of eyelets. It would be unfurled by tugging on the rope in a similar fashion to hoisting a ship’s sail. This design came to be known as the “twin-pole” sail.
An underwater test by Schweickart and Kerwin on 18 May showed that it would work, but that its pole sections might separate under stress. A locking nut was modified, the shade’s weight was reduced, and Teflon inserts were placed into the eyelets to reduce friction. Thereafter, the remainder of the work ran without a hitch.
Meanwhile, the option to deploy a sunshade from the scientific airlock had been revived and was gaining momentum, with a concept known as “the parasol.” Tests showed that a combination of coiled springs and telescoping rods could fit inside a standard airlock canister and could be deployed smoothly. Jack Kinzler, chief of JSC’s Technical Services Division and a close friend of Pete Conrad, jury-rigged it from a parachute canopy and telescoping glass-fibre fishing rods in hub-mounted springs.
A technician bought the fishing poles in Houston and Kinzler himself requested a tube from the sheet-metal shop and a large section of parachute material. “The machine shop fastened the four fishing rods to my base,” Kinzler told the NASA oral historian. “I fastened the base to the floor of our big high-bay shop area. We fastened the cloth to the rods and long lines to the tips of each rod. I lowered the big overhead crane to floor level and swung my four lines over the crane hook. Everybody came over for a demonstration … I raised the crane back up, letting out excess line, ‘til I had enough clearance, then let the crane pull all four lines simultaneously. It looked like a magician’s act because our came these fishing rods, getting longer and longer. They’re dragging with them fabric. They get all the way to where they’re fully out and all I did was let go and it went sshum. So the springs were on each corner and they came down and laid out right on the floor just perfectly. Everybody was impressed!”
It was decided to use standard space suit material—nylon, Mylar, and aluminium—for the shade itself, although little data existed on the performance of nylon when exposed to long-term vacuum and solar ultraviolet radiation. A decision was taken to cover all three sunshade types with an ultraviolet-resistant material, known as “Kapton,” but this proved problematic, because its weight might make it more difficult to stow and deploy properly.
Senior managers were in disagreement. Skylab Program Manager Bill Schneider felt that MSFC’s twin-pole sail was most likely to succeed, although JSC Director Chris Kraft thought it was too heavy. Kraft felt the development of the SEVA sail should continue, in case the twin-pole should fail its tests. During a final review at the Kennedy Space Center on 19 May, Kinzler’s parasol was chosen as the primary method (he would later receive a Distinguished Service Medal from NASA for his work) and on the 24th, the flight readiness review endorsed it. Having an astronaut standing in the hatch on an EVA was undesirable, since it would come at the end of a long, 22-hour day for the crew and the contamination effects of the command module’s thrusters on the ATM were unknown. Equally, the twin-pole concept did not meet with the approval of flight surgeons, who were aghast at the prospect of such a complex task so early in the mission. They also felt that the work might jeopardise Skylab’s medical objectives. For his part, Pete Conrad felt that Kinzler’s design was the simplest, safest, and quickest method … and hence most likely to succeed.
It was expected to be more than sufficient for the 28-day mission of Conrad, Kerwin, and Weitz, although the twin-pole and SEVA sails would be carried as a backup and deployed at a later date if the condition of the parasol deteriorated. The review also postponed the launch by five days, until 25 May, thereby allowing JSC and MSFC engineers to apply finishing touches to their hardware.
Years later, Schweickart praised the efforts of the industrial and NASA workforces to save Skylab during those frantic days. “I probably got a little bit of sleep,” he recalled, “but most of the team who worked with me at Huntsville never slept for four days! It was totally round-the-clock and it was not just the resources of the centre; it was all of the resources of the whole aerospace industry. Anything that we wanted, you simply called somebody and they turned inside out. Three different suppliers would manufacture some thermal material or some device overnight. They would work on it 24 hours themselves. It would be there on the company’s private Learjet the next morning. It was unbelievable how hard people worked.”
“Borrowing” aircraft—and cars—got a few engineers and branch chiefs into hot water. Bob Schwinghamer, head of the materials lab at MSFC, remembered lending the keys of a centre director’s car to a colleague … and then promptly forgetting to return it and receiving a severe verbal roasting the following morning. On another occasion, Schwinghamer was working late, until after the security staff had locked the perimeter gates. “If I call these damn security guys, they’ll be here in two hours,” he recalled. He decided to climb the fence, almost twice his height and topped by an ominous overhang of barbed wire. “I cut a big gash in my butt,” he concluded, “and fell off the fence and fell to the ground. Just when I hit the ground, two headlights came on. These darned security guys drove up and slammed up the brakes and jumped out.” One of the guards, who had previously nailed Schwinghamer for speeding, recognised him, grinned, and let him go.
To sum up: “We didn’t let anything deter us. A lot of funny stuff happened on our way to the Skylab … I was getting in hot water all the time and it was day and night. We did all kinds of stuff like that at that time, but we got [the parasol] built.”
Such comic anecdotes did not detract from the physical consequences of such a punishing workload. Ed Smylie, head of the Crew Systems Division, remembered one of his branch chiefs literally collapsing with exhaustion as he left work late one evening. Yet the sense of teamwork and camaraderie was unmistakable. Joe Kerwin felt the same. “It was a great team,” he reflected. “I look on Apollo 13 as the supreme test … for the Mission Control team. The Skylab problem was the supreme test for the engineering team. Both the contractors and the civil servants joined together, as one, and they figured out what the problem was.” To illustrate his nostalgia for the good old days, Kerwin recalled the motel accommodation during their time at MSFC, which charged seven dollars per night for a room with black and white television and eight dollars for colour. …
As NASA approached resolution on the question of how to repair the workshop, a formal inquiry into the cause of the Skylab mishap was set in motion by NASA Administrator Jim Fletcher on 22 May. He asked Bruce Lundin, head of the Lewis Research Center, to lead the investigation board. Reviews of launch data had already shed light on what had transpired. Sixty-three seconds into the Saturn V’s ascent, when it was obscured from the tracking cameras by thick cloud, the micrometeoroid shield had prematurely deployed, “standing out” a few centimetres from the hull of the workshop, and had very quickly been ripped off, like the skin of a banana, in the supersonic airflow. “At this time,” noted Lundin’s report, published on 30 July 1973, “vehicle dynamic measurements, such as vibration, acceleration, attitude error, and acoustics indicated strong disturbances. Measurements which are normally relatively static at this time, such as torsion rod strain gauges, tension strap breakwires, temperatures, and [solar array] position indicators, indicated a loss of the [shield].”
As a result of this failure, others followed: the separation of the micrometeoroid shield caused part of it to wrap around the No. 2 solar array and break the latches on the No. 1 array. Ten minutes into the flight, as planned, the second stage of the Saturn separated, firing its retrorockets to withdraw from the payload … and the plumes of those retrorockets quickly impinged on the No. 1 array, breaking its hinge and totally shearing it off. This incident was noted in Lundin’s report as “the 593 Second Anomaly.” Telemetry from this point showed a sudden loss of temperature readings and inexplicable voltage dropouts, which the board took as indicators that the array had physically separated from the workshop. “The effect of retrorocket plume impingement was observed almost immediately,” the report continued, “on the [No. 2 array] temperature and on vehicle body rates.” Under normal circumstances, the two arrays would have been freed from their attachments by a small explosive charge and spring-loaded hinges would have automatically unfurled them. Unfortunately, the No. 1 array was gone and its companion was so clogged with debris as to be effectively “pinned” to the side of the workshop and could only partially open.
In its concluding remarks, Lundin’s report settled on a number of possible causes for the failure of the micrometeoroid shield. The most likely one was an internal pressurisation of its “auxiliary tunnel”—a tunnel which served as a wiring conduit and was designed to vent pressure as the Saturn V rose through the atmosphere—due to imperfect seals and fittings. Pressures may have become high enough, about a minute after launch, to slightly raise the shield into the supersonic flow, ripping it off, with the result that it broke the latches on the No. 1 array and part of it became wrapped around the No. 2 array. When the second stage’s retrorockets fired, their exhaust finally tore the No. 1 array from its hinge.
The fundamental “human” cause, Joe Kerwin told the NASA oral historian, was that the designers of the micrometeoroid shield did not communicate effectively with the aerodynamicists and properly protect it from the supersonic airstream. In fact, failure to recognise such issues during half a decade of development was blamed on a decision to treat the micrometeoroid shield as a subsystem of the Saturn V, based on a flawed presumption that it would be structurally integral to the rocket. “As a result,” noted Joe Kerwin, David Hitt, and Owen Garriott in Homesteading Space, “the shield was not assigned its own project engineer, who could have provided greater project leadership. In addition, testing focused on deployment, rather than performance during launch.” One of the recommendations made by Lundin’s board was for more effective and comprehensive project oversight.
Of course, the state of the arrays and the reason for the No. 2 array being unable to properly unfurl could only be speculated until the arrival of Conrad’s crew and the presence of human eyes to physically see what was amiss. If debris was the problem, a repair method was acutely needed and engineers from MSFC set to work on a cable cutter (which looked like a large set of tree loppers) and a universal tool with prongs to pry and pull open the jammed array. Both tools came from A.B. Chance Company, a manufacturer of equipment for power companies, and both were designed to operate on the end of a 3 meter pole.
In Homesteading Space, an interview was noted with NASA systems engineer Chuck Lewis, who made the initial contact with A.B. Chance and secured the rapid delivery of the tools aboard a light aircraft. When the A.B. Chance product manager, Cliff Bosch, arrived at MSFC, he was joined by Lewis and backup crewmen Schweickart and Story Musgrave to begin sorting out the most effective tools. “The one thing they had that was really neat,” Lewis recounted, “was this scissor-like cutter that they used to clip electrical cables. The guys at re-engineered that in about a day and a half to provide some extra mechanical advantage because … we knew what sort of load it was going to take for those jaws to get through that and whether they were going to be able to pull on it.”
On 19 May, the tools were successfully tested in MSFC’s water tank, with the Skylab mockup specially “modified” with fragments of metal wire bundles, shards of bolts, and other objects representative of a failed micrometeoroid shield. Conrad, Kerwin, and Weitz took their turns underwater, evaluating the tools, prying debris away from the array, and completing the whole procedure safely. The tools had already left for the Kennedy Space Center when a certification review ruled that the pointed tips of the cutter were hazardous. New heads with blunt tips were quickly prepared and changes were made at the launch site.
Now, however, the time for talking was over. Years later, in her book Rocketman, Nancy Conrad related that her late husband’s response to the seemingly endless testing was typically direct and to the point: “Just get me up there, goddamn it!”
This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next weekend’s article will continue the commemorative look back at the trials and tribulations of Skylab and the endeavors of its first crew.
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