Astro-sisters install new batteries on ISS in last all-female spacewalk this mission
This will be their last walk together as Koch will return to Earth next week after more than 10 months onboard.

A pair of spacewalking astronauts successfully wrapped up battery improvements outside the International Space Station on Monday, completing a job begun last fall.
NASA’s Jessica Meir and Christina Koch installed the last new battery in a set of six launched to the orbiting lab in September. They also removed two old batteries in their second spacewalk in under a week to upgrade the station’s solar power grid.

astronauts Christina Koch, left, moves away as Jessica Meir, right, exits a hatch as they prepare to install batteries for the International Space Station's solar power grid during the spacewalk on Monday. Image credit: AP[/caption]During last Wednesday’s spacewalk, Koch’s helmet lights and the camera came loose. She later found a faulty latch in the helmet assembly and replaced it before floating out Monday.
Another batch of six new batteries will be launched to the orbiting lab this spring to complete the power upgrade. The old batteries, meanwhile, will be discarded in a supply ship.
These oversized, boxy batteries keep all the space station’s systems running when the outpost is on the night side of Earth, drawing power from the sprawling solar wings. They’re not easy to handle: Each is about a yard, or a meter, tall and wide, with a mass of about 400 pounds (180 kilograms.)
“That’s why it’s so meaningful for us today to be out here, on the day we honour Martin Luther King Jr., who paved the way not only for us, but so many that have a dream,” Koch said.
It was their last spacewalk together, at least during this mission.
Morgan and Italian astronaut Luca Parmitano will venture outside Saturday to complete repairs to a cosmic ray detector on the space station. The science instrument’s cooling system had to be replaced, an intricate job requiring four spacewalks.

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