Top Ten US EVA Missions of All Time: No. 6—'We Can Fix Anything'

The salvation of Skylab, perhaps more so than any previous endeavor, validated the importance of Extravehicular Activity (EVA). Photo Credit: NASA

The salvation of Skylab, perhaps more so than any previous endeavor, validated the importance of Extravehicular Activity (EVA). Photo Credit: NASA

Construction and maintenance of an Earth-circling laboratory is nothing new in the 21st century, for dozens of humans from a multitude of nations have toiled in low-Earth orbit to assemble the International Space Station (ISS) since 1998. Yet more than four decades ago, a pair of critical EVAs were performed outside the United States’ first space station, Skylab, and their purpose was not to assemble it, or even to maintain it, but to save it from abject failure. On 14 May 1973, Skylab rose into orbit aboard the final Saturn V booster, but at some stage during ascent the station’s micrometeoroid shield was torn away in the supersonic airstream. So too was one of its two electricity-generating solar arrays, whilst the other became so clogged with debris that it refused to unfurl. For 10 days, NASA engineers on the ground battled to come up with a workable plan for Skylab’s first crew—Commander Charles “Pete” Conrad, Science Pilot Joe Kerwin, and Pilot Paul Weitz—to effect a successful repair and keep the infant station alive.

With their launch scheduled for the stroke of 9:00 a.m. EDT, the morning of 25 May was particularly peaceful for the three astronauts. “This was the least well-attended Apollo launch in history,” Joe Kerwin recalled, “because everybody had to go home and put the kids back in school. We arrived at the command module and looked inside and it was a sea of brown rope under the seats and under the brown ropes were all these different umbrellas and parasols and sails and also the equipment that we had selected to try and free up the solar panel, which was a pretty eclectic collection of aluminum poles that could be connected together, and a Southwestern Bell Telephone Company tree-lopper with brown ropes to open and close the jaws. Some of it we’d seen, some of it we hadn’t!”

The astronauts were unperturbed. Indeed, as their Saturn IB booster cleared the tower of Pad 39B and roared into the clear morning sky, Conrad declared that his crew could fix anything. Launch came precisely on time and kicked off an eight-hour orbital ballet to rendezvous with the crippled Skylab later that same afternoon. Their initial orbit was gradually refined by four maneuvers to a near-circular path to intercept the space station on their fifth orbit. “Up until this time,” recalled trajectory and rendezvous specialist Cathy Osgood in a NASA oral history, “our rendezvous [procedure] had been to rendezvous the first day, after about five orbits. If you didn’t rendezvous by about the fifth orbit, the astronauts’ work day had been so long that they’d have to be facing a docking situation when they were just absolutely exhausted; so, all up until this time, the astronauts themselves wanted to get it all done the first day.”

Little did anyone know that the first day in space for Pete Conrad and his crew would run to no less than 22 hours. …

Launched atop the final Saturn V, the mission of Skylab almost ended before it had even begun. Photo Credit: NASA

Launched atop the final Saturn V, the mission of Skylab almost ended before it had even begun. Photo Credit: NASA

Conrad’s call of “Tally-ho the Skylab!” as a steadily brightening star on the horizon drew closer masked, at first, the seriousness of what the astronauts were about to face. The micrometeoroid shield was gone, as was one of the two solar arrays, whilst the second was so jammed with debris that it could not deploy properly. “When Pete finally got a good look at Skylab,” his widow Nancy Conrad wrote in her 2005 book, Rocketman, “he got the same feeling as you would when seeing a classic car you’d invested four years of your life in restoring now mangled in a heap in the town junk yard.” As Weitz took pictures, Conrad performed a flyaround inspection of the station, quickly ascertaining that Skylab’s scientific airlock was not cluttered with debris, thereby making the deployment of a special “parasol,” built by the Johnson Space Center (JSC) in Houston, Texas, a realistic option, and asserting his conviction that a Stand-Up EVA (SEVA) with the cable cutter should be enough to free the jammed solar array.

The first order of business was a “soft docking” at Skylab’s forward port at 5:56 p.m., engaging capture latches but not retracting their Apollo command module’s docking probe to ensure a firm metallic embrace. For a few minutes, the astronauts ate a quick dinner and prepared for the stand-up EVA. “A full hard dock wasn’t desirable at this point,” wrote David Hitt, Owen Garriott, and Joe Kerwin in their book Homesteading Space, “because of the likelihood that they’d undock again shortly. The docking system needed to be dismantled and reset after a hard dock.” With all three men fully suited, Conrad undocked from Skylab at 6:45 p.m., depressurized the cabin, and opened the side hatch. With Kerwin hanging onto his ankles to provide stability, Weitz reached out and used the modified tree loppers and a kind of “shepherd’s crook” to free the jammed array. It should have been an occasion of euphoria for Weitz, who had not been scheduled to perform an EVA at all on this mission. Unfortunately, despite his sterling efforts, it did not go well.

At first, he positioned himself with his upper body poking through the hatch. Kerwin passed him three sections to assemble a 15-foot (4.5-meter) pole with the loppers at the end, whilst Conrad kept the spacecraft steady. “We had seen … that there was a piece of bolted L-section from the thermal shield that had been wrapped up around the top of the solar wing,” Weitz recalled in his NASA oral history, “and apparently the bolt heads were driven into the aluminum skin. We thought maybe we’d just break it loose, so we got down near the end of the solar array and I got a hold of it with the shepherd’s crook.” However, as Weitz heaved on it, he was actually pulling the command module toward Skylab. In the meantime, Conrad had the unenviable task of keeping the spacecraft a mere 2 feet (60 cm) from the station and preventing the unwanted oscillations from causing a collision. The work was harder because a third of his field of view was blocked by the command module’s open hatch.

Prolonged solar exposure had already caused Skylab's outer skin to blister, as evidenced by this image from Pete Conrad's mission. The scientific airlock aperture through which the parasol was extended is clearly visible. Photo Credit: NASA

Prolonged solar exposure had already caused Skylab’s outer skin to blister, as evidenced by this image from Pete Conrad’s mission. The scientific airlock aperture through which the parasol was extended is clearly visible. Photo Credit: NASA

“It made for some dicey times,” Weitz later recalled. As the two vehicles entered orbital darkness, he paused in his work, then resumed as they flew within range of the tracking station. The shepherd’s crook was getting him nowhere and the torrent of four-letter words from all three astronauts even prompted the capcom in Mission Control to ask them to modify their language—for they were on an “open mike.”

The main problem, Conrad explained, was that a strip of metal had become wrapped across the solar array during the separation of the micrometeoroid shield. Its bolts had tangled themselves in the array and none of Weitz’s actions to cut the strap, even with the loppers, were having any effect. “Rather than cutting it across the short way, we were trying to cut along the long way,” Weitz said, “and didn’t have enough muscle with that thing, because it was 6-8 feet (1.8-2.4 meters) out ahead of me and I was pulling on a line to try to do it.” The metal strap, ironically, was fairly narrow, but it was riveted fast, and Conrad knew they did not have a hope of breaking it using the tools in the command module.

The attempt was scrapped, and, after 40 minutes, the astronauts were instructed to close the hatch and re-dock with Skylab. Even this proved easier said than done: getting the pole, loppers, and shepherd’s crook back inside in a safe and speedy manner led to an inadvertent thump to Conrad’s helmet and an accidental kick to Kerwin. The capcom’s advice to modify their language again fell on deaf ears, as a few more “unscientific” words were uttered.

Docking, wrote Nancy Conrad (probably selecting a few of her late husband’s words), “was a bitch.” On their first attempt, the probe did not engage with the drogue and no fewer than three further tries were also fruitless. “Pete gave Weitz the controls,” Nancy continued, “depressurized the command module and opened the tunnel hatch. He and Joe dove head-first into the bank of circuits and gizmos, Pete cussing a blue streak as he sorted through wires, cutting and splicing like a pissed-off Maytag repairman trying to get a dryer to work again.” Weitz then set about rewiring in the right-hand equipment bay, removing the electrical inter-lock which prevented the main latches from actuating until the capture latches were secure. After an hour or so of re-routing and connecting wires, bypassing electrical relays for the capture latches on the tip of the probe, and skinning knuckles—and another bout of undesirable vocabulary—Conrad used the service module’s thrusters to bring the two collars into direct contact, triggering a dozen capture latches in a cacophony like machine gunfire.

They were at Skylab to stay.

The sheer audacity of the EVAs performed by Skylab's first crew should not be underestimated. In spite of the extravehicular experience gained on Apollo and Gemini, very little "repair" work had ever been done, and none as intricate and mission-critical as that which Skylab demanded. Here, Joe Kerwin works to free the jammed solar array. Photo Credit: NASA

The sheer audacity of the EVAs performed by Skylab’s first crew should not be underestimated. In spite of the extravehicular experience gained on Apollo and Gemini, very little “repair” work had ever been done, and none as intricate and mission-critical as that which Skylab demanded. Here, Joe Kerwin works to free the jammed solar array. Photo Credit: NASA

In their NASA oral histories, both Kerwin and Weitz paid tribute to a conversation with their rendezvous instructor, Jake Smith, in February 1973, in which the minutiae of how to accomplish this kind of “backup docking procedure”—which wires to cut and which to splice together—had been explored. Had it failed, there was a very real possibility that the mission would have ended. Now, though, with Apollo safely docked, an ecstatic Mission Control were able to advise the crew to grab a bite to eat and some sleep before entering Skylab the following morning. It was 11:50 p.m. EST. Their first day in space had been a long one—more than 22 hours, prompting Paul Weitz to quip that “union rules wouldn’t allow us to work that long anymore!”

Over the following days, they deployed the makeshift parasol through the scientific airlock, which helped to reduce temperatures inside the station, but another EVA was acutely necessary to fix Skylab’s clogged solar array. Under the direction of backup commander Rusty Schweickart, a repair scenario was devised. It required Conrad and Kerwin to move to the antenna boom at the forward end of Skylab and attach a cable cutter to the debris; this would serve as a makeshift “hand-rail” to enable them to reach the jammed solar array and cut the metal strap. Once there, they would have to break a frozen hydraulic “damper” on the array. The damper’s purpose had been to prevent the array from deploying too fast, but when it partially unlatched after launch, the hydraulic fluid quickly froze solid.

Conrad and Kerwin would connect a Beam Erection Tether (BET) between the array and the airlock. When the debris had been removed, it was hoped that pulling on the tether would break the damper. During a series of underwater suited simulations on 2 June, Schweickart and fellow astronaut Ed Gibson practiced the procedure and found that, aside from a lack of foot restraints, it was workable. The lack of foot restraints, and lights, hand-holds, and visual aids, was not an oversight; it reflected the fact that there had never been any intention to perform maintenance on Skylab. There were several planned EVAs, for example, to replace film cassettes, but actual repairs were considered too dangerous. “I had been working a lot of the spacewalk procedures for the film retrieval,” Gibson told the NASA oral historian, “so it was natural to then start developing procedures for the repair of the station.”

However, some managers remained jittery about the idea of attaching a cable cutter to debris, but there was little alternative. On the evening of 4 June, Schweickart talked Conrad through the task and, as the astronauts slept, a list of tools and assembly instructions were transmitted to Skylab’s teleprinter. The crew reviewed these procedures and rehearsed the steps inside the station on 6 June, with a suited Kerwin, minus his helmet, practicing the movement of the poles and grabbing a mock target with the cutters, before finally venturing outside in the early hours of the following morning.

Artist's concept of Pete Conrad working with the Beam Erection Tether (BET) to free the clogged solar array. Image Credit: NASA

Artist’s concept of Pete Conrad working with the Beam Erection Tether (BET) to free the clogged solar array. Image Credit: NASA

Since the airlock was in the middle of the Skylab “cluster,” the fully-suited Weitz had to ensure that Conrad and Kerwin had all of their tools and tethers before he depressurized them. Weitz then retreated into the multiple docking adaptor. The hatch was opened at 10:23 a.m. EDT on 7 June, just before the station entered the dark portion of its orbit. Conrad assembled the tools—six rods, each measuring five feet (1.5 meters) in length, screwed together, the cable cutter fitted, and rope from the backup SEVA sail tied to the cutter’s pull rope—and then he and Kerwin moved into position alongside the antenna boom. The unlikely contraption thus enabled them to operate the cutter from several metres away … just enough to reach the jammed array.

As Kerwin tried to close the cutters against the debris, it became apparent that he was “slipping,” because he could not establish a secure position for himself. For a half-hour, with one hand steadying himself and the other trying to close the cutters, he struggled fruitlessly to complete the work. As his pulse rate began to climb, he decided on an alternative course of action and shortened his own tether, in an effort to steady himself against the edge of the station. It worked, and after 10 minutes he was able to tell ground controllers that the cutters were securely fastened to the debris. Next, he pulled on the lanyard to operate them, but nothing happened. Conrad inched his way, hand-over-hand, along the length of the beam to see what was amiss, and precisely as he reached the cutter “end,” the jaws snapped shut, freeing some of the metal strap at 2:01 p.m. EDT and hurling him “ass over teakettles” into space. Fortunately, Conrad’s tether restrained him from moving far from Skylab and the jammed array now stood at 20-degrees-open.

The frozen damper, however, still resisted normal deployment and the holes on the solar array were smaller than on the ground model, so he could only attach one of the two hooks on the BET. The two men heaved on the tether, but without success, until Conrad placed his feet on the frozen hinge, stooped to fit the tether over his shoulder, and “stood up.” Kerwin pulled on the tether, and, this time, the solar array suddenly released and sprang into its full, 90-degrees-open position. Both astronauts were flung outward by the catapult-like effect and arrested by their tethers. After three hours and 25 minutes, the two laughing astronauts re-entered Skylab and the needles of the electricity meters dramatically jumped, signaling success. By the next day, 8 June, solar heating had fully extended the array and it was generating 7 kilowatts of much-needed power. From just 40 percent power, the station’s output suddenly increased to around 70 percent.

With Conrad and Kerwin’s success, the confidence of NASA in the abilities of spacewalkers increased substantially. “Before that, there was still the legacy of problems with EVA during Gemini,” recalled Rusty Schweickart. “Apollo, of course, made a big difference, but that was sort of running around on the [lunar] surface in gravity again; so here was EVA of a massive scale in weightlessness that we never anticipated; [we] did it with flying colors, everything worked just fine, never had a problem and saved the mission.”

For Kerwin, his first spacewalk was electrifying—there was nothing, he said later, which could possibly compare to looking at the Earth through the visor of a space suit—but also demonstrated that the underwater training on the ground was harder than the real thing in orbit. “No matter how well they weight you out” in the water tank, he said, “you’re not really weightless. If your body is turned upside down, yes, the suit is neutrally buoyant, but you’re jammed up against the shoulders and the blood is rushing to your head. If you can do it under those circumstances, you’re going to find that it’s a piece of cake in zero-G.”

 

 

This is part of a series of articles to commemorate 50 years of U.S. Extravehicular Activity. Tomorrow’s article will focus on the spacewalks of STS-88 in December 1998, which embarked on the monumental “Wall of EVA” to build the International Space Station (ISS).

 

 

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