For over 16 years, a bright star has nightly graced Earth’s skies, easily visible to the naked eye, serving to pique our curiosity and inspire our minds. Now, in 2015, the International Space Station (ISS) is fully assembled and in the fully operational phase of its lifetime, and we can look back on the immense EVA accomplishment—which currently stands at 187 U.S. and Russian spacewalks and is expected to pass 190 before the end of the year—with a sense of awe and astonishment. In fact, more Extravehicular Activities have been completed in support of ISS construction and maintenance than in any previous space program, U.S. or Russian, and the International Partners have scaled and overcome a daunting “Wall of EVA” which appeared virtually insurmountable a little over two decades ago.
That wall was first assaulted by the crew of STS-88 in December 1998, the first shuttle mission to deliver hardware to orbit—specifically Node-1, otherwise known as “Unity,” and a pair of Pressurized Mating Adapters (PMAs 1 and 2)—and connect them to Russia’s Zarya Control Module, launched two weeks earlier. The crew comprised Commander Bob Cabana, Pilot Rick Sturckow, and Mission Specialists Jerry Ross, Nancy Currie, Jim Newman, and Russian cosmonaut Sergei Krikalev and were tasked with performing a series of complex EVAs to integrate the two components and prepare the nascent station for subsequent expansion. Originally, when the STS-88 crew was announced in August 1996, they were expected to perform “two scheduled spacewalks to connect power and data cables,” but as their training wore on, this developed into three excursions.
The Wall of EVA had been observed with much trepidation by NASA since the earliest days of the development of Space Station Freedom, the predecessor of the ISS. In the fall of 1990, an External Maintenance Task Team (EMTT), led by engineer Charles Price of the Johnson Space Center (JSC) in Houston, Texas, and veteran EVA astronaut Bill Fisher, found that the assembly and maintenance of the station would likely require between 2,282 and 3,276 hours of EVA, per year … a far cry from NASA’s officially stated goal of around 500 hours per annum. Combined with other factors, Congress demanded a redesign of the station and NASA implemented several major restructuring plans over the following years, yielding a smaller number of shuttle assembly flights. Significantly, the individual elements of the enormous backbone-like truss structure—which would support a network of electricity-generating solar arrays, radiators, and other critical hardware—would be pre-fabricated on the ground, rather than assembled during shuttle flights, thus cutting down the number of EVAs by about 50 percent. By the eve of STS-88’s launch, it was anticipated that around 160 spacewalks would be required between 1998 and 2003 to build the station.
A year earlier, in the fall of 1997, the last pre-ISS shuttle-based EVAs took place, allowing final evaluations of the tools and techniques required for construction tasks. “This is our last chance to look at this, before we employ it somewhere down the line on Space Station,” explained former astronaut Greg Harbaugh, then serving as head of the EVA Project Office at JSC. “We have to recognize that EVA is very much fundamental to the success of station. It is going to be an almost everyday occurrence for the next several years, so we’d better get used to it. If we have any misgivings about EVA, it’s time to get those behind us. Starting with STS-88, we are into what we call the ‘EVA Wall’ and we better be ready to step up to it. It’s a gigantic undertaking, something like three times the amount of EVA work that we’ve ever done in the history of the American space program.”
Following the robotic mating of Zarya and the Unity/PMA “stack,” to create a structure which rose almost 70 feet (21 meters) out of Shuttle Endeavour’s payload bay, it was intended that Ross and Newman would commence the first EVA of the new era. They left the airlock hatch at 5:10 p.m. EST on 7 December 1998, three days after liftoff, and floated into the blackness of space. Since their assignment to STS-88, the two men had spent 540 hours in EVA-specific training, including more than 240 hours underwater in the Neutral Buoyancy Laboratory (NBL) at JSC.
“We have a minimum set of tasks that we have to accomplish, and then we have a large number of tasks that are get-aheads for future missions, so that they have a better chance of success on their flights,” explained Bob Cabana before launch. “Our third EVA is not packed right now; if we have problems on either of the first two EVAs, we can offload some of those tasks to the third one in order to make up. Everything is planned out such that you want to accomplish the things that you absolutely have to get done, and then, hopefully, you’ll have a little time to do some of these get-ahead tasks to help out down the road.”
“If you design spacewalks appropriately and pay attention to the details, no one task on any one of the spacewalks should be very difficult,” said Ross, before the launch. “However, when you look at the number of tasks we have, especially on our first spacewalk, and all those tasks have to go in sequence and have to go successfully, I think … the first spacewalk we have is a pretty challenging one. It’s not overly challenging from a physical standpoint, but if we did run into very many stumbling blocks or problems out there, Jim and I would really be scrambling to try to get it all done within the amount of time that’s permitted by the suit expendables.”
Assisted by Rick Sturckow, who served as the Intravehicular (IV) crew member on Endeavour’s aft flight deck, Ross and Newman worked quickly and ahead of the timeline. In the opening, Ross remarked on a beautiful orbital sunset, as the shuttle passed into darkness, high above the South Atlantic Ocean. “EVA is always a challenge and there are always surprises,” Greg Harbaugh said before the flight, “but this is certainly within the range of what I would consider a pretty doable set of tasks. This is not incredibly demanding … this is handling hardware that was designed to be handled in EVA. It’s robust; it’s strong. This is construction work we’re doing and these are two very capable engineers going out to do this work. Having said that, the complexity level is probably medium.”
With Ross riding on the end of the shuttle’s Remote Manipulator System (RMS) mechanical arm, his initial task was to install mating plugs and jumper cables to route electrical power through Unity, whilst Newman released the launch locks which had secured wiring along the exterior of PMA-2. In total, the two men mated 40 data and power cables and connectors, running the entire length of the Zarya-Unity combo, and well as EVA handrails and other tools to aid future spacewalkers. At one stage, commands were issued to activate a pair of U.S.-Russian voltage converters, which fed electrical power between the two modules for the first time and brought Unity’s systems to life at 10:49 p.m.
Neither astronaut made much small-talk during the EVA, which Ross had already described as “the most critical,” but in the latter stages the two men began to chatter more frequently.
“Hey, Jerry, what’cha doing?” asked Newman at one point.
“Oh, I’m just hangin’ around, building a space station,” came the reply.
The “perfect electrical continuity between the two modules,” as NASA described it, enabled the activation of Unity’s internal systems, including its avionics and computers. Shortly before returning to Endeavour, Ross removed thermal covers from a pair of Multiplexer-Demultiplexers (MDMs) after Unity’s own heaters had taken over temperature control. Newman was also raised by Currie on the RMS for observations of a pair of stuck TORU navigational antennas. Twenty-seven minutes before the end of the EVA, Ross—who was making his fifth career spacewalk—officially eclipsed the achievement of fellow astronaut Tom Akers as the most experienced U.S. spacewalker. By the time he and Newman returned inside Endeavour at 12:31 a.m. EST on 8 December, after seven hours and 21 minutes, Ross had accumulated a total of 30 hours and eight minutes working in a pressurized suit in the vacuum of space. This also placed him just behind Russian cosmonaut Anatoli Solovyov as the second most experienced spacewalker in the world at that time.
Late the following evening, Cabana and Sturckow used Endeavour’s thrusters in a “staccato” fashion for about 22 minutes to slightly boost the orbit of Zarya-Unity, as the rest of the crew prepared for Ross and Newman’s second EVA. This got underway at 3:33 p.m. EST on 9 December, and the spacewalkers moved to install a pair of early S-band antennas on the exterior of Unity in order for ground controllers to monitor its systems and provide basic videoconferencing capabilities for the station’s first long-duration crew. Next, the two men pressed on with removing launch restraint pins on Unity’s four radial hatches and fitted a sunshade over the two MDMs. Newman was also lifted atop the RMS to free the first of the two jammed TORU antennas. He slightly nudged the antenna with an extendable, 10-feet-long (3.3-meter) grappling hook, which finally persuaded it to pop out into its fully deployed configuration. The spacewalkers returned to Endeavour’s airlock at 10:35 p.m. EST, after a little more than seven hours.
The only event which marred EVA-2 was the loss of a thermal cover, which drifted away from Ross’ reach, despite his sterling effects to keep everything tethered. Later, he had nothing but praise for the EVA training team. “I’d just like you to pass on to a lot of friends back there that spend a lot of long hours working hard to get us ready to go fly, I just really do appreciate it,” he said. “All the training they went through to get us ready is really paying off.” However, there was a caveat, for there was simply no way of training for the sheer magnificence and grandeur of actually spacewalking, high above the Home Planet. “I think the guys do everything they can on the ground,” added Ross, “but they can’t quite replicate what God can give us up here.”
Finally, at 3:33 p.m. on 12 December, Ross and Newman floated into the vacuum of space for what turned out to be an EVA of six hours and 59 minutes, primarily focused upon preparing the ground for the second shuttle assembly crew, that of STS-96 in May 1999. The first task for Ross and Newman was the releasing of ties from a quartet of cables installed earlier in the mission, in order to relieve tension. Mission Control had noticed from television views that leaving the cables “as is” would offer insufficient “play” in them to accommodate cyclical heating and cooling during the orbital “day” and “night” periods. Next, they checked an insulation cover on PMA-2 and attached a bag of tools, including wrenches, power grippers, ratchets, and foot restraints, onto the side of PMA-1.
They disconnected cables and Ross used the grappling hook in an effort to free the second jammed TORU antenna. Although the antenna proved a little stubborn at first, he tapped and nudged it several times, until it finally rolled out from its spool into the fully deployed configuration. Finally, the spacewalkers performed a photographic survey in aid of future missions. Late in the spacewalk, Ross also tested the Simplified Aid for EVA Rescue (SAFER), which had previously been trialed on shuttle missions STS-64 and STS-86, and which would provide a self-rescue capability in the event that astronauts became physically separated from their tethers or from the ISS itself.
However, he found that the SAFER consumed nitrogen propellant far more quickly than anticipated. “I don’t know at this point … if that was a true indication of the consumption of the gas or whether it was an erratic pressure transducer,” admitted Greg Harbaugh in the aftermath of EVA-3. “We have to go do some homework and study there before we can declare this a complete victory in the sense that the SAFER worked perfectly. But, clearly, it was worth doing. It’s always important to demonstrate the parachute and that’s why I pushed so hard to have this test done.”
By the time Ross and Newman returned inside Endeavour, they completed a total of 21 hours and 22 minutes on the first three EVAs of the ISS era, which established Ross as the most experienced U.S. spacewalker, with 44 hours and nine minutes, and Newman in third place with 28 hours and 27 minutes. “We have set in place the third brick in the EVA Wall and done it with a flourish,” he told a press conference after the conclusion of EVA-3. “We have gone above and beyond the call of duty, for the third time demonstrating we knew how to plan for, train for and execute EVAs that are demanded … by the Space Station assembly program. This is a great start.”
And so it was. The STS-88 crew returned to Earth a few days later, completing the first phase of an endeavor which continues to this very day.
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 Mission 41B in February 1984, which included the first-ever untethered EVA by Bruce McCandless.
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