Meir and Koch replaced nickel-hydrogen batteries with newer, more powerful lithium-ion batteries as they upgraded ISS power systems on the Port-6 truss structure, NASA said. Wednesday's spacewalk kicked off around 3:50 a.m. PT and was originally scheduled to last six and a half hours.
The astronauts completed all of their scheduled tasks and accomplished an extra battery-moving, "get-ahead task" as a bonus. This was Meir's second spacewalk and Koch's fifth.
Their next spacewalk is set for Jan. 20 -- a sign that all-female spacewalks are becoming more common -- when they'll replace more batteries. On Jan. 25, NASA's Andrew Morgan and ESA's Luca Parmitano will go out again to work on the Alpha Magnetic Spectrometer, an instrument that sifts through cosmic ray particles.
First published at 5:36 a.m. PT on Jan. 15. Update, 5:55 a.m. PT: Adds more detail. Update, 11:15 a.m. PT: Reflects end of spacewalk and results.