The International Space Station crew is gearing up for the second of two spacewalks aimed at replacing aging nickel-hydrogen batteries with new lithium-ion units. Two astronauts will leave the Quest airlock at around 7 a.m. EST (12:00 GMT) Jan. 13, 2017, for an estimated six-and-a-half-hour-long excursion.
The first spacewalk, Extravehicular Activity 38, occurred last Friday, Jan. 6, and saw Expedition 50 Commander and NASA astronaut Shane Kimbrough, along with NASA’s Peggy Whitson, install adapter plates next to three robotically installed lithium-ion batteries. The primary work area for the EVA was on the 3A power channel on the starboard 4 truss segment.
The truss assembly for the ISS has eight large Solar Array Wings. Each is attached to a power channel with three strings of batteries. Originally, each of those strings included two nickel-hydrogen batteries in series.
To complete the upgrade to lithium-ion batteries, which are lighter and more efficient, only one battery per string is needed. To complete the connection, an adapter plate is placed where the second nickel-hydrogen battery was situated. A data link cable connects the battery with the plate.
EVA-39 will be the second spacewalk in a week to upgrade the outpost’s power system. This time, the work will be on the opposite side of S4 and focus on the 1A power channel and be nearly identical to the first in terms of primary tasks.
The lead spacewalker will be Kimbrough. He will be designated EV-1 and wear the suit with red stripes. With him will be European Space Agency astronaut Thomas Pesquet. He will be designated EV-2 and wear the suit with no stripes.
Just like the previous spacewalk, this EVA comes after the ground-based robotics team finished swapping out batteries that were brought up by the Japanese Kounotori 6 cargo ship.
The batteries were located on the Exposed Pallet in the unpressurized section of the craft. In December, the robotic Canadarm2 moved the pallet to the Mobile Base System on the starboard side of the station’s Integrated Truss Assembly.
Over the last couple days, using Canadarm2 with the Dextre Special Purpose Dexterous Manipulator attached, the final three lithium-ion batteries were moved from the EP and placed in their appropriate locations on the 1A power channel.
A total of six nickel-hydrogen batteries have been stowed on either the EP or temporarily on Dextre. During the spacewalk, one old battery will be moved on top of one of the adapter plates for permanent storage.
The 3A power channel has been checked out and is fully operational. The 1A channel will be activated during the EVA after the adapter plates are put into place.
Over the weekend, some post-EVA robotics will work to move the last four nickel-hydrogen batteries from Dextre to the EP. A total of nine of the 12 replaced units will be placed on the pallet for disposal when the Kounotori 6 spacecraft leaves later this month.
This spacewalk will be Kimbrough’s fourth and Pesquet’s first. It will also be the 197th in assistance of space station assembly and maintenance for the U.S. orbital segment over the last 18 years.
Video courtesy of NASA
NOTE: While this article was written by Derek Richardson, it was originally published at SpaceFlight Insider. Feel free to head over there to read all the stuff they write about!