NASA astronauts Chris Cassidy and Robert Behnken are scheduled to depart the International Space Station’s Quest airlock Wednesday for a spacewalk to complete battery replacement activities to upgrade one of two power channels on the station’s far starboard truss (S6 Truss). The upgrade includes removing six aging nickel-hydrogen batteries and replacing them with three new lithium-ion batteries and the adapter plates that complete the power circuit to the new batteries.
The duo will set their spacesuits to battery power about 7:35 a.m. EDT Wednesday, signifying the start of their spacewalk, which will last between six and seven hours. NASA will begin its live coverage on NASA Television and the agency’s website at 6 a.m.
In a prior spacewalk June 26, Cassidy and Behnken began the work to complete the upgrade to this initial power channel, additionally completing some of the tasks originally scheduled for today. The remaining tasks for today are to install one more lithium-ion battery and one more adapter plate and remove the sixth nickel-hydrogen battery that will no longer be used. NASA animation depicts the originally scheduled spacewalk activities. The new lithium-ion batteries arrived on a Japanese cargo ship last month.
New tasks added for tomorrow’s spacewalk include loosening the bolts on the nickel-hydrogen batteries that will be replaced during two future spacewalks to complete the power capability upgrade on the far starboard truss and complete the station’s battery replacement work that began in January 2017 with the first series of power upgrade spacewalks.
Cassidy and Behnken also will route power and ethernet cables in preparation for the installation of a new external wireless communications system with an enhanced HD camera and to increase helmet camera coverage for future spacewalks. To support future power system upgrades, they also will remove a device called an “H-Fixture” that was installed before the solar arrays were launched to the space station.
This will be the 229th spacewalk in support of space station assembly and maintenance. Cassidy again will be extravehicular crew member 1, wearing the spacesuit with red stripes, while Behnken will be extravehicular crew member 2, wearing the spacesuit with no stripes. It will be the eighth spacewalk for each astronaut.