A new U.S. astronaut has slipped into the Top Ten list of the world’s most experienced spacewalkers, following Friday’s successful Extravehicular Activity (EVA) to complete the activation of new power-producing solar arrays on the International Space Station (ISS). Expedition 65 astronaut Shane Kimbrough, making the ninth spacewalk of his career, was paired for the third time in nine days with France’s Thomas Pesquet of the European Space Agency (ESA).
They wrapped up a complex week of spacewalking which has now installed a pair of Boeing-built ISS Roll-Out Solar Arrays (iROSAs) on Power Channels 2B and 4B of the station’s aging P-6 truss. And with the conclusion of today’s six-hour and 45-minute EVA, Kimbrough now sits jointly in sixth place next to Russia’s Fyodor Yurchikhin on the list of “Spacewalking Supremos”. He reshapes an impressive Top Ten team, eight of whose members—including EVA heavyweights and former NASA Chief Astronauts Chris Cassidy, Bob Behnken and Peggy Whitson—are from the United States. It also closes out a remarkable month of four EVAs outside the sprawling orbital outpost.
In addition to a heavy plate of science tasks, June has been an exceptionally busy month for spacewalking, with no less than four EVAs performed from the U.S. Operational Segment (USOS) and the Russian Operational Segment (ROS).
On 2 June, first-time spacewalkers Oleg Novitsky and Pyotr Dubrov, wearing Russian space suits, spent seven hours and 19 minutes installing external experimental hardware and readying the long-serving Pirs module for removal from its Earth-facing (or “nadir”) berth on the station’s Zvezda module.
Specifically, the cosmonauts disconnected external mechanical links between Pirs and Zvezda, relocated spacewalking hardware—including the Strela (“Arrow”) crane—and reconfigured antennas. After almost two decades as part of the ISS, the departure of Pirs and the freeing-up of its docking port will allow Russia’s long-delayed Nauka (“Science”) lab to take up residence on the outpost later this summer.
Only days later, following the arrival of SpaceX’s CRS-22 Dragon cargo ship, Kimbrough and Pesquet dived directly into EVA preparations for what were originally anticipated to be a pair of spacewalks on 16 and 20 June to install the first set of Boeing-provided iROSA arrays on Power Channels 2B and 4B on the aging P-6 truss at the far-port-side tip of the station’s Integrated Truss Structure (ITS).
As reported by AmericaSpace in January, three pairs of iROSA arrays will be installed to cover (and partially “shadow”) six of the eight “legacy” Solar Array Wings (SAWs), affording a power hike of 20-30 percent in anticipation of future ISS expansion and customers’ burgeoning payload needs.
Overnight on 10/11 June, the Robotics Officer (ROBO) in Mission Control remotely commanded the station’s 57.7-foot-long (17.6-meter) Canadarm2 to detach the first pair of iROSA arrays from Dragon’s trunk on their Integrated Payload Assembly (IPA) and “temp-stow” them on a Payload and Orbital Replacement Unit Accommodation (POA) on the station’s truss.
Elsewhere, Kimbrough and Pesquet worked to check out their space suit helmet cameras and lights, configured tools, printed checklists and participated in computerized EVA procedures reviews with ground controllers.
Their first spacewalk on 16 June ran for seven hours and 15 minutes and quickly ran behind the timeline when Kimbrough experienced difficulties with the Display and Control Module (DCM) on his suit, as well as a pressure spike in the sublimator responsible for maintaining adequate cooling.
He was obliged to return briefly to the Quest airlock to work through a DCM restart and sublimator recycle procedure, before he and Pesquet resumed work. By the end of the EVA, the duo successfully installed the iROSA onto the mast canister on Power Channel 2B, but time constraints and an interference issue meant they were unable to install the electrical cables and drive the final bolts to unfurl the array.
As such, their second EVA last Sunday—originally dedicated to the second iROSA installation on Power Channel 4B—was partially consumed by these leftover tasks. Yet even this second spacewalk did not fully escape the gremlins, for Pesquet had to assist when Kimbrough’s helmet camera and light assembly came loose.
The men spent six hours and 28 minutes completing the electrical connections and successfully deploying the Power Channel 2B array to its full 60-foot (18.2-meter) length. They then adjusted a pair of tensioner bolts to secure the array in its final configuration, before pressing into the Power Channel 4B work and releasing the upper iROSA support beams.
By this stage, however, NASA had announced plans for a third EVA on 25 June to wrap up the installation task. Kimbrough and Pesquet—making their fifth spacewalk together, following two others in January and March of 2017 during their Expedition 50 increment—departed the Quest airlock at 7:52 a.m. EDT.
But even with so much experience between them, Pesquet has been quick to stress that spacewalking is far from routine. “No matter how many EVAs you do, it’s never just casual when you venture outside of the @Space_Station,” he tweeted Thursday. “After all, it’s the most extreme environment human beings have ever been exposed to.”
Assisting Kimbrough and Pesquet were their Expedition 65 crewmates Mark Vande Hei, who led the Suit-Up procedure, and Megan McArthur, who was responsible for Canadarm2 operations. And at the Johnson Space Center (JSC) in Houston, Texas, a Mission Control team led by Flight Director Pooja Jesrani also featured veteran spacewalker Drew Feustel and Canadian Space Agency (CSA) astronaut Jenni Sidey at the CapCom console.
Working rapidly, Kimbrough and Pesquet secured the second iROSA onto its mounting bracket and unfurled its two halves, before pressing on with the electrical connections. Soon after 1 p.m. EDT, Kimbrough completed the final electrical connections and within the hour the deployment process was complete. Both power channels on the P-6 truss have now received fully functional iROSA upgrades and the Station Power, Articulation and Thermal Control (SPARTAN) officer in Mission Control declared fully functionality and good power generation.
With the completion of today’s EVA at 2:37 p.m. EDT after six hours and 45 minutes, Kimbrough now resides jointly in sixth place with Russia’s Fyodor Yurchikhin on the list of the world’s most experienced spacewalkers. His career total of 59 hours and 28 minutes exactly matches that of Yurchikhin, who like Kimbrough has logged nine EVAs. And on Pesquet’s first EVA with Kimbrough last week, he soundly eclipsed the 19 hours and 30 minutes of STS-111’s Philippe Perrin to seize the title of the most experienced French spacewalker. Pesquet has since pushed his lead further and his EVA total now stands at 33 hours exactly, just nine minutes shy of Italian astronaut Luca Parmitano, who remains the most seasoned non-U.S. and non-Russian spacewalker.