Expedition 50 Commander Shane Kimbrough and Flight Engineer Thomas Pesquet spent almost six hours working outside the International Space Station (ISS), earlier today (Friday). During U.S. EVA-39—the 39th spacewalk performed from the station’s Quest airlock, in U.S.-built Extravehicular Mobility Units (EMUs) and performed without a Space Shuttle being present—the two astronauts hooked up three new adapter plates and associated electrical connectors for new lithium-ion batteries. As outlined previously by AmericaSpace, over the next few years, a total of 24 lithium-ion batteries will replace 48 aging nickel-hydrogen batteries aboard the Integrated Equipment Assemblies (IEAs) of the station’s four main power-producing truss segments.
In conjunction with last week’s U.S. EVA-38, the first six lithium-ion units have now been installed and activated on the starboard-side S-4 truss segment. The 12 old batteries from S-4 have been removed, with nine of them destined for disposal aboard Japan’s current H-II Transfer Vehicle (HTV-6), later in January, and the other three kept in a dormant configuration as potential on-orbit spares. The remaining 18 lithium-ion batteries will arrive, six at a time, aboard the next three HTVs, which are currently targeted to launch at yearly intervals in early 2018, early 2019 and early 2020. These batteries will be installed into the IEAs aboard the starboard-side S-6 truss and the port-side P-4 and P-6 trusses of the station’s expansive Integrated Truss Structure (ITS).
Although today’s U.S. EVA-39 was Kimbrough’s fourth career spacewalk—following his stellar performance last week, as well as during a pair of shuttle-based EVAs in November 2008—it marked the first outing for Pesquet, who becomes only the fourth French astronaut to venture outside his spacecraft in Earth orbit in a pressurized suit. Just a few weeks shy of his 39th birthday, Pesquet is also the youngest-ever French spacewalker, following in the footsteps of Jean-Loup Chrétien, Jean-Pierre Haigneré and Philippe Perrin.
Following EVA-38, which installed three new adapter plates and electrical connectors for the three lithium-ion batteries on the Power Channel 3A “side” of the S-4 truss, robotics officers in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, worked from Sunday through Thursday on the complex procedure to duplicate these efforts on the opposing Power Channel 1A. Three new lithium-ion batteries were successfully installed, via the Dextre robotic manipulator, setting all the pieces in place for Kimbrough and Pesquet’s EVA.
With Kimbrough designated as “EV1”, with red stripes on the legs of his EMU for identification, and Pesquet wearing a pure white suit, the spacewalkers rose early Friday. Assisted by Expedition 50 crewmates Peggy Whitson and Oleg Novitsky, they undertook the standard pre-EVA protocols of pre-breathing on masks and In-Suit Light Exercise (ISLE). At length, Whitson and Novitsky maneuvered the pair and their tools through the hatch from Quest’s inner equipment lock to its outer crew lock and sealed them off. At 5:45 a.m. EST, depressurization of the crew lock got underway, reaching a condition of near-vacuum. At 6:22 a.m., Kimbrough and Pesquet transferred their suits’ critical life-support utilities from station power to internal battery. This action officially kicked off U.S. EVA-39.
Kimbrough and Pesquet first performed “buddy checks” of the status of each other’s suits, before heading along the airlock spur and along the starboard side of the ITS, towards the S-4 truss. The pair worked with impressive speed: by 7 a.m., Pesquet was already in the process of breaking torque on the bolts holding down one of the three remaining adapter plates on the HTV External Pallet. Within the next hour, the pair had not only removed two of the plates and successfully installed them into the 1A IEA, but Kimbrough had also managed to complete a couple of “get-ahead” tasks, namely a reconfiguration of Solar Array Blanket Box (SABB) clamps and the stowage of a Pump Flow Control Subassembly (PFCS) cable.
Moving well ahead of the timeline, the astronauts had completed all three adapter plate installations and associated data-link cables within three hours and the Electrical Systems Officer in Mission Control reported good electrical power and data-flow paths to the new batteries. They had also relocated one of the old nickel-hydrogen batteries to its new role as a dormant spare, ready to be used again, if needed. Kimbrough and Pesquet were now able to press ahead into a range of get-ahead tasks, starting with photography of the “Rat’s Nest”—an area of the station’s Z-1 truss, so named because of the jumble of cables and umbilicals snaking through its vicinity—and moving into the replacement of a camera pan and tilt assembly on the Mobile Transporter (MT) reel assembly. This task was satisfactorily concluded shortly after 10:30 a.m. EST, some four hours into the EVA.
An hour later, yet another pair of get-aheads had been ticked off the “jobs jar” list: the retrieval of a pair of handrails and the swapping-out of a worksite interface adapter on the 57.7-foot-long (17.6-meter) Canadarm2. By now well past the five-hour mark, Kimbrough and Pesquet set about cleaning up their respective worksites and headed back to the airlock. U.S. EVA-39 formally ended at 12:20 p.m. EST, after five hours and 58 minutes. This duration now leaves Kimbrough with a career total of 25 hours and 22 minutes of spacewalking time, across four EVAs. Meanwhile, Pesquet becomes the fourth Frenchman and only the tenth European citizen to perform a spacewalk.
With today’s work, the Expedition 50 crew has left the S-4 truss with six fully functioning lithium-ion batteries, together with three old nickel-hydrogen units as dormant spares, for potential future use. Of the 12 total nickel-hydrogen batteries, the current tally has six already loaded aboard the HTV External Pallet for disposal, three others temporarily stowed on Dextre and the other three in place on S-4 as spares. Over the weekend, the three temp-stowed batteries will be transferred from Dextre over to the HTV-6 External Pallet. Next Tuesday (17 January), the Pallet will be robotically removed from its current perch on a Payloads Orbital Replacement Unit (ORU) Accommodation (POA) worksite and replaced aboard the HTV-6 spacecraft itself.
This will leave HTV-6 fully loaded with nine old batteries for disposal during a destructive dive into Earth’s atmosphere on 27 January. Looking ahead, the next set of lithium-ion batteries are targeted to fly aboard HTV-7, which is tentatively scheduled for a spring 2018 launch. The remainder of the new batteries will then arrive at the space station, via HTV-8 and HTV-9, in early 2019 and early 2020, respectively. Each of the new batteries is capable of supporting a lifespan of more than a decade.