Two NASA astronauts switched their spacesuits to battery power this morning at 6:35 a.m. EST Expedition 61 Flight Engineers Christina Koch and Jessica Meir are venturing out into the vacuum of space for about six-and-a-half hours to finish replacing nickel-hydrogen batteries with new lithium-ion batteries that store and distribute power generated by the station’s solar arrays on the station’s port truss. The lithium-ion batteries provide an improved power capacity for operations with a lighter mass and a smaller volume than the nickel-hydrogen batteries.

Watch the spacewalk on NASA TV and on the agency’s website.

Meir is designated extravehicular crew member 1 (EV 1), wearing the suit with red stripes, and with helmet camera #11. Koch is designated extravehicular crew member 2 (EV 2), wearing the suit with no stripes, and her helmet camera is labeled #18.

Commander Luca Parmitano of the European Space Agency (ESA) and NASA Flight Engineer Andrew Morgan will assist the spacewalkers. Morgan will control the Canadarm2 robotics arm and Parmitano will provide airlock and spacesuit support.

Learn more about station activities by following the space station blog, @space_station and @ISS_Research on Twitter as well as the ISS Facebook and ISS Instagram accounts.