For the fourth time this year, a pair of astronauts ventured outside the Quest airlock of the International Space Station (ISS) earlier today (Wednesday, 28 October) and completed a number of activities in readiness for the future expansion of the orbital outpost to receive its first Commercial Crew visitors from 2017 onward. Expedition 45 astronauts Scott Kelly and Kjell Lindgren, both embarking on their first career EVAs, spent seven hours and 16 minutes successfully installing thermal covers on the Alpha Magnetic Spectrometer (AMS), tying down Multi-Layer Insulation (MLI) on one of four Main Bus Switching Units (MBSUs), laying cables in readiness for Commercial Crew operations, and lubricating the second Latching End Effector (LEE) on the space station’s 57.7-foot-long (17.6-meter) Canadarm2 robotic arm. However, the astronauts’ work took slightly longer than anticipated and another task—to install a Non-Propulsive Vent (NPV) back onto the Tranquility node—was deferred to a later date. Known as an “ISS Upgrades EVA,” today’s work comes on the heels of three months of detailed planning and was made possible when a “window” opened in the October-November timeframe, ahead of what ISS Operations Integration Manager Kenny Todd expects to be an “extremely busy” winter of Visiting Vehicle traffic.
As is customary in the ISS era, much of the training for today’s EVA-32—the 32nd U.S. “Stage” EVA, executed out of the Quest airlock, in U.S.-built Extravehicular Mobility Unit (EMU) suits and without a space shuttle being present—has been completed with the astronauts already in orbit. Kelly, who is now at the 60-percent-complete stage of his one-year mission with Russia’s Mikhail Kornienko, was launched in late March, whilst Lindgren rocketed into orbit on 22 July, requiring them to utilize their pre-flight EVA Skills training, manuals, checklists, and presentations and in-suit exercises in Quest. Earlier this month, Lindgren described his EMU as a “marvelous miniature spaceship” to his 44,500 Twitter followers and thanked the engineers, instructors, and divers who had trained him to use the suit. For his own part, Kelly posted a suited self-portrait in the airlock and told his 587,000-strong Twitter audience that he was “Getting my game face on for a spacewalk.”
Early this morning, assisted by fellow Expedition 45 crewmates Kimiya Yui of Japan—who served in the Intravehicular (IV) role, choreographing EVA-32 from inside the station—and Russia’s Sergei Volkov, the two spacewalkers undertook 60 minutes of “pre-breathing” on masks, during which time the inner “equipment lock” of Quest was depressed from its ambient 14.7 psi to 10.2 psi. Upon completion of this well-trodden pre-EVA protocol, Kelly and Lindgren donned and purged their EMUs and the airlock’s atmosphere was repressurized back up to 14.7 psi.
This allowed the men to enter a nominal pre-breathing regime, lasting 50 minutes, followed by a further 50 minutes of In-Suit Light Exercise (ISLE). The latter was first trialed during the third EVA of the STS-134 shuttle mission in May 2011—which, coincidentally, was commanded by Kelly’s identical twin brother, Mark—and serves to rapidly remove nitrogen from the spacewalkers’ bloodstreams, thereby avoiding a potentially fatal attack of the “bends” and skirting the need for the EVA crew to “camp out” overnight in Quest. At length, Yui and Volkov transferred the fully-suited astronauts and their equipment, including the Simplified Aid for EVA Rescue (SAFER) units, affixed to the lower segment of their life-sustaining backpacks, from the equipment lock into the outer “crew lock.” Hatches between the locks were closed at shortly before 7:20 a.m. EDT and depressurization began.
When it reached 5 psi, it briefly halted for pressure and leak checks, then resumed until the crew lock achieved a condition of near-vacuum. EVA-32 officially commenced at 8:03 a.m. EDT, when Kelly and Lindgren transferred their suits’ life-support utilities from ISS power over to internal batteries. Venturing outside first, Kelly—designated “EV1,” bearing red stripes on the legs of his suit for identification—became the 212th human being since Alexei Leonov and the 120th American citizen since Ed White to perform a spacewalk. Meanwhile, in order to negate the need to return to the airlock during the remainder of the EVA, Lindgren (“EV2,” clad in a pure white suit) passed out bags of equipment and then joined Kelly to become the world’s 213th and America’s 121st spacewalker.
“After being cooped up in the @Space_Station for the past 215 days,” tweeted Kelly’s identical twin brother, Mark, “@StationCDRKelly got to go outside for a walk.” The twins were selected together as space shuttle pilots with the 16th class of NASA astronauts, way back in May 1996. Both have now flown four space missions: Mark has served twice apiece as a shuttle pilot and commander, whilst Scott has piloted one shuttle mission, commanded another and went on twice helm the ISS as its long-duration skipper.
Following standard “buddy checks” of each other’s suits and tools, the pair set about their initial tasks by 8:40 a.m., with Kelly taking the MLI bag along the airlock “spur” and translating along the starboard side of the Integrated Truss Structure (ITS) to reach the MBSU location on ExPRESS Logistics Carrier (ELC)-2, at the junction of the S-1 and S-3 segments. Working quickly, he began tying down the MLI at the MBSU, in order to provide a clear movement path for the station’s Mobile Base System (MBS), which offers a foundation for Canadarm2 to translate along the truss. Kelly was finished on this task shortly after 10 a.m. EST, and, just a few minutes behind the timeline, he pressed ahead into the next of his scheduled tasks.
Meanwhile, Lindgren moved the Ballscrew Lubricating Tool (BLT)—previously used by Expedition 42’s Terry Virts to grease one of Canadarm2’s Latching End Effectors (LEE), during EVA-30 in February—and moved it over to External Stowage Platform (ESP)-2, to be employed by Kelly later in the spacewalk. ESP-2 resides on the port side of Quest and would be the location from which Kelly would conduct his intricate lubrication work. Next, Lindgren collected an Articulating Portable Foot Restraint (APFR) from ESP-2 and translated out to the 14,800-pound (6,700-kg) AMS, which is positioned on the Upper Inboard Payload Attach Site on the S-3 truss segment. He had reached the particle physics instrument by about 9:20 a.m., some 80 minutes into the EVA. Working quickly, Lindgren secured the APFR in place within minutes and set to work wire-tying a small “wedge” of MLI material between two of AMS’ radiators, which then expanded, tent-like, to provide thermal protection. He then installed small and large MLI blankets over the AMS pumps, which have experienced some degradation in recent months, and was finished by 10:30 a.m., about 2.5 hours after leaving the Quest airlock.
Following his MBSU work, Kelly moved into perhaps the most complex stage of EVA-32: lubricating the Canadarm2 LEE. Since the 57.7-foot-long (17.6-meter) arm consists of two LEEs—allowing it to effectively “inchworm” its way along the football-field-sized truss structure—it was necessary for both “ends” to be thoroughly lubed, in order to resolve issues of “stickiness” and sluggish motion, which have created higher than expected electrical currents. To be fair, the Canadian-built arm has been aboard the ISS since April 2001. One LEE was successfully lubed by Terry Virts in February, with Kelly slated to tend to the LEE on the other end of the arm.
His work got underway shortly after 11 a.m. EST, about three hours into EVA-32, when he set up the APFR and was presented with the looming face of the LEE, whose extended latches and central ballscrew bore an uncanny similarity to the fearsome tripods in War of the Worlds. Since lubrication of the LEE was never intended to be done by spacewalkers, the BLT—which comprises a probe, wire ties, and lots of tape—was employed by Virts in February and, today, by Kelly, to apply lubricant from a Grease Gun.
After several “dry runs,” he set to work applying lubricant shortly before 12:30 p.m., some 4.5 hours after departing the Quest airlock. Working “in the blind” at several stages, Kelly first attacked the LEE’s central ballscrew, before moving onto the equalization brackets and latch deployments rollers for its four extended latches. His task was slow, methodical and incredibly fiddly and NASA later reported that “greasing numerous parts of the robotic arm took somewhat longer than anticipated,” leading to the decision to forego the lubrication of one component, and Kelly’s work was done by 1:30 p.m. EST.
Elsewhere, Lindgren had wrapped up his AMS activity and moved into retrieving a cable bag, containing power (“Purple-White”) and data (“Orange”) cables for future operations with Pressurized Mating Adapter (PMA)-3—soon to be transferred from its current perch on the Tranquility node to the space-facing (or “zenith”) side of the Harmony node—and one of two International Docking Adapters (IDAs). He initially “temp-stowed” the forward part of the cable onto a handrail on the Destiny laboratory, then routed the aft section toward the Unity node, with the orange cable first, then the purple-white cable. Lindgren’s cable work was completed by 1:20 p.m. EDT.
By this point, almost 5.5 hours into EVA-32, it was evident that the spacewalk would run for longer than its planned 6.5 hours, and the astronauts were told to defer the NPV installation task until a later date. All primary activities had been successfully concluded and Kelly and Lindgren cleaned up their respective worksites and made their way back to the airlock. Repressurization was finalized at 3:19 p.m. EDT, with EVA-32 wrapped up after seven hours and 16 minutes. When placed into context, this EVA—the 189th spacewalk of the ISS era, since the initial excursion by STS-88 astronauts Jerry Ross and Jim Newman, way back in December 1998—has pushed the cumulative time spent by humans working outside this multi-national habitat in the heavens to 1,184 hours, which represents 49.3 days, or more than seven weeks working in near-total vacuum.
Next up for Kelly and Lindgren is EVA-33, currently planned for Friday, 6 November, which will see the spacewalkers also spend around 6.5 hours working outside the space station. As outlined in a previous AmericaSpace article, this second EVA will see the men exchange roles, with Lindgren as EV1 and Kelly as EV2. Its principal objective can trace its heritage back to November 2012, when Expedition 33 spacewalkers Suni Williams and Aki Hoshide attempted to isolate an ammonia leak in the cooling system of the P-6 element of the ITS. It was speculated at the time that the leak possibly arose following an Micrometeoroid Orbital Debris (MMOD) strike to its Photovoltaic Radiator (PVR) or perhaps age-induced cracking, but by mid-2012 the leak had increased to 5.2 pounds (2.4 kg) per year, which represented about 10 percent of P-6’s original ammonia load. This, in turn, raised the alarming risk that the critical 2B power channel—which carries major electrical loads across the whole ISS—could have been forced to shut down before the end of 2012.
Williams and Hoshide’s EVA isolated the 2B coolant loop and used the Trailing Thermal Control Radiator (TTCR) for subsequent cooling, allowing engineers to pinpoint the exact location of the ammonia leak. However, six months later, in May 2013, ammonia “snow” was seen emanating from the 2B power channel, which necessitated a contingency EVA by Expedition 35 spacewalkers Chris Cassidy and Tom Marshburn. The pair were unable to locate the source of the leakage but removed, replaced, and tested a suspect Pump Flow Control Subassembly (PFCS), which was expected to yield additional clues for investigators in their search for a solution. More than two years later, Kelly and Lindgren’s task on U.S. EVA-33 will be to restore the P-6 truss cooling system to the original state it was in prior to the Williams/Hoshide EVA.
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