NASA’s first all-female spacewalk is scheduled for Friday morning.

Astronauts Christina Koch and Jessica Meir had been scheduled to make the excursion from the International Space Station on Oct. 21, but NASA changed the date so that they could make an urgent repair to the station’s power system. 

"@Space_Station update: our first all-female spacewalk with @Astro_Christina and @Astro_Jessica will be Thursday or Friday to replace a faulty battery charge-discharge unit," NASA chief Jim Bridenstine said Tuesday on Twitter

 The spacewalk is now scheduled to begin at 7:50 a.m. ET on Friday. NASA will live-stream the outing beginning at 6:30 a.m. ET.

The astronauts will replace a “battery charge/discharge unit” that failed Oct. 11, after new lithium-ion batteries were installed during a previous spacewalk. The malfunction hasn’t jeopardized the safety of the crew, the space station or any of the onboard experiments, according to NASA.

The all-female spacewalk will be the second of what NASA has called a “spacewalk bonanza,” with 10 outings scheduled through December. Three other spacewalks that had been planned for this week and next week have been postponed, according to the agency.

Originally, NASA had planned an all-female spacewalk in March. But that outing — which was to have involved Koch and NASA astronaut Anne McClain — was scrapped because there weren’t enough spacesuits of the right size available on the station.

NASA caught flak for the circumstances surrounding that cancellation. "Gotta love the irony that because women have never spacewalked together before there aren't enough suits so the spacewalk can't happen," one Twitter user said at the time. "What a joke."

This will be Meir’s first spacewalk and Koch’s fourth.