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How to Save a ‘Great Observatory’ - Step Three: Enter the Saviours

Its solar arrays and high-gain antenna properly deployed, the GRO drifts in the inky blackness to begin its nine-year mission of exploration. Photo Credit: NASA

Twenty-one years ago, this week, five astronauts exchanged anxious glances aboard Space Shuttle Atlantis. In the pilots’ seats at the front of the flight deck were veterans Steve Nagel and Jerry Ross, with crewmates Ken Cameron, Jay Apt and robot arm operator Linda Godwin glued to the aft windows behind them. Outside, at the far end of the payload bay, the enormous Gamma Ray Observatory (GRO) – all 17,000 kg of it – hung at the end of the arm, awaiting deployment into space. This was not just any satellite. As one of NASA’s four ‘Great Observatories’, it was part of an effort to examine the Universe across the entire electromagnetic spectrum, revealing the mysteries of the cosmos in a clarity never before seen. A year earlier, the first Observatory, the Hubble Space Telescope, had gotten off to a rocky start when a problem was found with its optics. Now, in April 1991, the second Observatory, GRO, was midway through its pre-deployment checkout when it suffered a major glitch of its own. The high-gain antenna – critical in enabling GRO to transmit data back to Earth – had failed to unfold.

Attempt after attempt – six in total – was made to open the antenna and Nagel and Cameron even tried shaking it loose with a burst from Atlantis’ manoeuvring thrusters. All were fruitless. Privately, Nagel never had much confidence in the latter procedure, “because the [robot arm] is so ‘spongy’ with the satellite on the end that you fire a jet and it doesn’t do anything…all the motion is damped out by the time it gets to the satellite”. Godwin tried moving it sharply, and stopping abruptly, but sharpness and abruptness were misnomers with the Canadian-built arm, which moved relatively slowly, and these efforts had no effect. Ross was by now stationed in the pilot’s seat, monitoring data, and glanced over at Nagel in the commander’s seat. Both men knew that an EVA was the only realistic option. Ross removed his wedding ring and handed it to Nagel.

“Steve,” he said, “I’m going downstairs to get ready.”

Nagel nodded. No more than a minute later, a call came up from Mission Control, asking them to do just that. Assisting the two spacewalkers was Cameron, who now found himself scurrying around Atlantis’ middeck to prepare a pair of two-part space suits for Ross and Apt. Before actually clambering into the two-piece space suits, electrical harnesses were attached to their ‘hard’ upper torsos to provide biomedical and communications links through the backpack. A wrist mirror and spiral-bound, 27-page checklist were placed on each suit’s left arm, followed by the insertion of a small fruit and nut food bar and water-filled drink bag. The next step was the connection of a black-and-white communications hat – famously nicknamed the ‘Snoopy cap’ since Apollo days – to the top of the torso.

When Jerry Ross closed the airlock for the final time on Mission 61B in late 1985, he could hardly have imagined that he would be the next astronaut to venture outside on the United States' next EVA. A spacewalk on STS-37 had long been planned...but the need to repair GRO could hardly have been anticipated. Photo Credit: NASA

Physically, the suits were nothing less than $2.5 million miniature spacecraft in their own right, consisting of ‘upper’ (above-waist) and ‘lower’ (below-waist) segments, together with helmet, gloves and backpack. The suits had been developed under a series of contracts with Hamilton Standard of Connecticut. Ross and Apt firstly pulled themselves into the lower torso, which featured joints at its hips, knees and ankles and a metal body seal closure for connecting to a ring on the upper torso. It also included a large bearing at its waist for greater mobility and allowed the astronauts to twist whilst their feet were held firmly in restraints.

After donning the trousers of the suit, their next step was to plug the airlock’s service and cooling umbilical into a display and control panel on the front of the upper torso. This would provide cooling water, oxygen and electrical power from the Shuttle until shortly before they were scheduled to go outside, thereby conserving the limited consumables available in their backpacks. The two men finally entered the airlock, where the upper torsos ‘hung’ on opposing walls and, through a half-diving, half-squirming motion, manoeuvred themselves into the top halves of their suits. With arms outstretched, and Cameron nearby to assist, they slipped themselves into the upper torsos and their waist rings were brought together, connecting the cooling water tubing and ventilation ducting of the long underwear and the biomedical sensors to their backpacks. Cameron helped them to lock the body seal closure rings at their waists. The hard upper torso was essentially a fibreglass shell under several fabric layers of a thermal and micrometeoroid garment. On its back, it held the life-support system and on its chest the display and control unit by which the spacewalker would manage oxygen, coolant and other consumables; in fact, due to the difficulties in seeing ‘down’ to read labels on the unit, the mirrors on the suits’ left wrists would help immeasurably. For additional ease, the labels were written backwards!

Next step: the gloves. Snapped into place on the wrist rings of the upper torso, these had silicone rubber fingertips to provide a measure of tactile sensitivity when handling tools in Atlantis’ cavernous payload bay. Finally, the enormous polycarbonate bubble helmets were lifted over the astronauts’ heads and clicked into place on the neck rings of their upper torsos. Over the top of each helmet was an assembly containing manually adjustable visors to shield their eyes from solar glare, together with two EVA lamps to illuminate work areas out of range of the Sun or the Shuttle’s own payload bay floodlights. Mobility in the neck rings was unnecessary, because the helmets were easily big enough to allow the astronauts to move their heads around. Unlike previous Apollo space suits, the modularised Shuttle ensemble, with its waist closure ring, eliminated the need for pressure-sealing zips and therefore had a much longer shelf life. Additionally, the use of newer, stronger and more durable fabrics enabled space suit engineers to design joints with better mobility, resulting in lower weight and a reduction in overall cost.

This training view of STS-37 astronauts Steve Nagel (left) and Jerry Ross in the forward flight deck brings to life the drama of the heart-stopping moments when GRO's high-gain antenna failed to open. Ross handed his wedding ring to Nagel, floated from his seat and went down to the middeck to get ready. Photo Credit: NASA

Jerry Ross and Jay Apt, by now floating motionless in Atlantis’ tiny airlock, were, in effect, small spacecraft in their own right. However, they were not yet ‘self-contained’, as their oxygen, electricity and cooling water were still being provided by the Shuttle’s systems; not until shortly before the two men ventured outside would they transfer to their suits’ life-support consumables. At length, a go-ahead came from Mission Control and Ross commenced the final depressurisation of the airlock and pushed open the outer hatch into the payload bay. Sunlight flooded into both of their faces and, beyond, the enormous bulk of the GRO hovered on the end of the robot arm.

It was a nervous time. In fact, on his previous EVAs, Ross had never gotten as excited or anxious as he did on the spacewalk to save GRO. “I didn’t know if we could fix it or not,” he told the NASA oral historian, “and here we are, on the spot to try to go out and fix this thing…and if we can’t, then we’ve got this great big lead weight. What are we going to do with it? We may not be able to bring it home, because the solar array’s already been deployed and the antenna’s partly released. Oh, man!” Nagel agreed. Without a functional high-gain antenna, GRO could have completed its mission, but it would have been very cumbersome to relay scientific data to the ground. Coming on the heels of the embarrassing start to the first Great Observatory mission – the Hubble Space Telescope – it was imperative that GRO be deployed in full working order.

Quickly, the two spacewalkers split up: Apt moved to the port side of the payload bay to set up tools, whilst Ross, on the starboard side, attended to the task at hand. Godwin moved the robot arm slightly to tilt the GRO towards him. “The antenna,” Ross said later, “was on the back side, facing the aft bulkhead of the orbiter, and the guys in the cockpit couldn’t see it from the aft windows.” By the time he reached the location of the antenna, Atlantis was passing out of direct communication with Mission Control – a Loss of Signal period – and Ross used the quiet time to position himself in such a way that he could shake it open. He knew that the antenna was relatively close to GRO’s hydrazine tanks, and he definitely did not want to ding those and risk having a highly-toxic leakage on his hands. By now, Nagel, Cameron and Godwin were getting views from the aft payload bay cameras on their monitors and were able to offer Ross some additional guidance. He gave the antenna a couple of lateral shakes. It still felt solid; immovable. A few more tries achieved a measure of success, as it started to loosen up a little.

 

In his career as an astronaut, Jerry Ross would practice the assembly of space station structures on his first flight, rehearse moving around a space station on his third, fly aboard a space station on his fifth and actually build the real thing on his sixth and seventh. With such vast EVA expertise, there could have been no one better placed to save GRO from the jaws of defeat. Photo Credit: NASA

“I was probably putting in 45-50 lb of force, is my recollection,” Ross said later, “and I could tell it was starting to walk out. Finally, it came free and swung out about 30-40 degrees from the stowed position.” It turned out that a thermal blanket had become ‘hung up’ on a bolt and Ross’ repair had taken just 17 minutes. He let out “a war whoop” and returned to the port side of the bay to join Jay Apt. The two men gathered their tools and Ross returned to GRO to begin the process of manually locking the antenna’s boom into its deployed position. “And that was a pretty good feeling,” he said. “I felt that I’d probably earned my keep for that day!” At one stage, Ross took a breather, moving close to Atlantis’ aft flight deck windows to grin at his crewmates inside the cockpit. Nagel snapped his photograph. It was a photograph which would return to haunt him – literally – a couple of years later…

At 5:36 pm EST on 7 April, some three orbits and more than 4.5 hours later than planned, Linda Godwin finally released a perfectly functional GRO from the grasp of the arm. The Great Observatory, with all the grace of a space-age diesel locomotive, drifted serenely away into the inky blackness to commence its mission. Ross and Apt had a ringside seat for much of this activity, for they were able to remain outside whilst the final checks on the observatory were performed. “During that period of time,” Ross told the oral historian, “Jay and I were allowed to stay outside on the spacewalk and to do a series of force measurements.” The intention was to understand the kind of loads an astronaut might experience whilst in and out of a foot restraint and Ross performed “a whole series of manoeuvres of turning wrenches, turning handles, manoeuvring myself…a whole series of things that we were recording the data so that we could get more information”. Years later, even the powerfully-built Ross remembered working up a vigorous sweat, which streamed into his eyes at one stage, such was the level of exertion and exhaustion.

The spacewalkers were supposed to be back inside Atlantis’ airlock in time for the actual GRO release. It did not entirely work out that way. “I think the only thing that was still in the airlock when we released the satellite,” said Ross, “were our toenails! Jay and I were pretty well outside of the hatch…and then they fired the jets to move the orbiter away. That was really cool. We were over North Africa at the time that we released it and we were above the satellite, looking down. That was a pretty awesome sight.”

The 'aces' of STS-37 celebrate on Atlantis' middeck. Spacewalkers Jerry Ross (front left) and Jay Apt (front right) hold the cards, flanking Linda Godwin, whilst pilots Steve Nagel and Ken Cameron float in the background. Photo Credit: NASA

Ross and Apt prepared dinner for their crewmates that night to celebrate a quite remarkable day. Yet STS-37 had barely reached its halfway point. On 8 April, the spacewalkers returned outside for their originally planned six-hour EVA to perform a series of Space Station Freedom locomotion tests. A 24-hour delay to their landing, caused by bad weather at Edwards Air Force Base, meant that they finally returned home to California on the 11th, after six days in space.

During his final approach, Nagel fell victim to an incorrect call on high-altitude winds and brought the orbiter down onto the runway a couple of hundred metres ‘short’. It was the first such ‘low-energy’ landing of the Shuttle programme and was not immediately noticeable to most spectators, since it was on a vast dry lakebed, but gained a lot of attention from Nagel’s fellow astronauts. Years later, Nagel would blame himself for not being aggressive enough when he rolled out onto final approach, but it made little difference to his career. His first Shuttle command had triumphed in the face of adversity, placed a brand-new Great Observatory, fully functional, into orbit, and had gone a long way towards demonstrating not only that NASA needed a permanent space station, but that it needed the capabilities of men and women in space.

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