STORY WRITTEN FORÂ CBS NEWSÂ & USED WITH PERMISSION
Picking up where they left off last week, two space station astronauts ventured back outside the outpost Wednesday to continue the replacement of aging batteries in the labâ€™s solar power system. Two more spacewalks later this month should complete the multi-year project.
Station commander Chris Cassidy and Crew Dragon astronaut Robert Behnken, floating in the Quest airlock, switched their spacesuits to battery power at 7:13 a.m. EDT to kick off their second spacewalk in five days, the 229th in station history and the eighth overall for both astronauts.
After checking safety tethers and collecting their tools, the astronauts floated outside and headed to the far right end of the space stationâ€™s power truss for another round of battery replacement work.
The space station is equipped with four huge solar array wings, each one feeding electricity into two circuits, or power channels. Each of the eight power channels originally included six nickel-hydrogen batteries â€” 48 in all â€” to provide electricity when the station is in orbital darkness.
But the original batteries are wearing out, and NASA is in the process of replacing all 48 with 24 more powerful lithium-ion power packs and circuit-completing adapter plates to take the place of batteries that were removed but not replaced.
During spacewalks in 2017, 2019 and in January this year, 36 old batteries in three of the four sets of solar arrays were replaced. Cassidy and Behnken are working to replace a final set in the stationâ€™s right-side outboard arrays.
Last Friday, they removed five of the six nickel-hydrogen batteries in one of the outboard power channels and installed two of three lithium-ion batteries and two of three adapter plates in their place.
During Wednesdayâ€™s work, they planned to finish power channel 1B and to loosen bolts securing batteries in power channel 3B. Before calling it a day, the astronauts planned to route cables for a new wireless communications system and to remove a no-longer-needed fixture on the power truss.
If all goes well, Cassidy and Behnken will venture back outside later this month to continue the battery swap outs for the final power channel, 3B. A fourth spacewalk is expected after that to finally finish the job.