Two NASA astronauts on the first of two spacewalks outside the International Space Station (ISS) made swift work to help with the replacement of old batteries with new lithium-ion units. They even had enough time left over to perform several get-ahead tasks. Extravehicular Activity (EVA) 38 began at 7:23 a.m. EST (12:23 GMT) on Jan. 6, 2017. It was performed by NASA astronauts Shane Kimbrough and Peggy Whitson. The goal was to install three adapter plates next to three lithium-ion batteries that were installed robotically late last week.
On New Year’s Eve, the ground-based robotics team used the Canadam2 and the smaller Dextre ‘hand’ to swap out four aging nickel-hydrogen batteries for three of six lithium-ion batteries. They were brought up last month by the Japanese Kounotori 6 cargo ship.
The new batteries were stored in the Exposed Pallet (EP) located in the unpressurized section of the Kounotori spacecraft. It was removed by the robotic arm last month and placed on the Mobile Base United on the ISS truss to allow for the installation work to begin.
The lithium-ion batteries are lighter and more efficient than the old nickel-hydrogen ones. As such, only six lithium-ion units are needed to replace 12 nickel-hydrogen batteries.
The space station’s truss assembly has eight large Solar Array Wings, each attached to a power channel with three strings of batteries. Each string of batteries contained two nickel-hydrogen units in series.
One lithium-ion battery, as well as an adapter plate, will replace two nickel-hydrogen units. A data link cable will connect the plate and lithium battery. Additionally, the top of the adapter plate can be used to store an old and depleted nickel-hydrogen battery.
The work area for the EVA and robotic operations was the Starboard 4 (S4) truss segment, which is where the 3A and 1A power channels are located. Today’s spacewalk primarily focused on the former, while next week’s spacewalk (Jan. 13) will focus on the latter.
Once outside the Quest airlock, Kimbrough translated to an equipment cart on truss near the work area to grab a foot restraint. He installed that on the S4 truss before moving to the EP to help Whitson grab two adapter plates.
They both then made their way to the work area to begin installation of the adapter plates. The first one was installed in a vacant slot. Kimbrough drove two bolts to attach it and then connected a data cable from the battery to the plate.
Next Kimbrough moved a nickel-hydrogen battery to the adapter plate for storage. In its place, he installed a second adapter plate the same way as the first.
Both Kimbrough and Whitson then moved back to the EP to grab the third and final adapter for this EVA. It was installed in a similar process as the other two.
Kimbrough then moved to the 1A channel on the opposite side of the truss. He finished loosening a bolt that had trouble during the robotics portion of this battery upgrade process. Meanwhile, the Electrical Systems Officer on the ground reported that the three newly installed batteries with their adapter plates were operating within specifications.
With all of that work done in some four hours, about an hour ahead of the EVA timeline, there was plenty of time for several get-ahead tasks. One was for Kimbrough to image the radiator panels on the Alpha Magnetic Spectrometer, located on the S3 truss segment next to the primary work area. This will be used to plan a future spacewalk for maintenance on the experiment.
Whitson, meanwhile, worked to remove a failed crew light atop a work cart. That proved to be one of the more difficult tasks of the spacewalk as the light refused to loosen. At one point, Kimbrough jokingly suggested using WD-40.
Eventually, the light was popped off and then stored for later repair.
A final get-ahead task was performed by Whitson. She worked on running an Ethernet cable into the S0 truss segment in advance of future spacewalks to prepare for the arrival of a second new docking adapter later next year.
With all of those items completed, it was time to come back in. The spacewalk officially ended at 1:55 p.m. EST (18:55 GMT) when the repressurization of the airlock began.
The total spacewalk time for EVA-38, the 196th in assistance of space station assembly and maintenance for the U.S. orbital segment over the last 18 years, was 6 hours, 32 minutes. The time for all 196 spacewalks is now 51 days and 6 minutes.
This spacewalk was Kimbrough’s 3rd EVA, bringing his total to 19 hours and 24 minutes, and Whitson’s 7th, bringing her total to 46 hours and 18 minutes, putting her at number 14 on the list for most spacewalk time.
On Sunday, the robotics team will begin swapping batteries on the 1A channel (five nickel-hydrogen batteries will be replaced with three lithium-ion) in advance of another spacewalk on Jan. 13, 2017. It will see Kimbrough go out with European Space Agency astronaut Thomas Pasquet. This will essentially be a duplicate EVA on the 1A side.
Written by: Derek Richardson
Original source: spaceflightinsider.com