Two astronauts completed a six hour and 39 minute spacewalk to swap out some old batteries on the International Space Station. 

NASA astronauts Anne McClain and Nick Hague on Friday were able to replace nickel-hydrogen batteries with newer, more powerful lithium-ion batteries on one pair of the space station's solar arrays, according to NASA. The space agency said the new batteries will provide improved capacity with a lighter mass and a smaller volume than the nickel-based batteries.

NASA livestreamed the spacewalk and also took questions during the mission.

NASA said this was the first spacewalk of 2019. The astronauts started at 8:01 a.m. ET and finished at 2:40 p.m. ET. 

The next spacewalk, which will also involve battery replacement work, is set for March 29 with NASA astronauts McClain and Christina Koch. If it goes according to schedule, it'll be the first all-female spacewalk in history.

Originally published March 22, 8:50 a.m. PT.
Updates, 11:02 a.m.: Includes additional information about the spacewalk; 1:52 p.m.: Reworked to reflect that the spacewalk has been concluded.