Astronauts Christina Koch (left) and Jessica Meir are scheduled to spacewalk together on Oct. 17 or Oct. 18, 2019.

We won't have to wait quite as long as we'd thought for the first all-female spacewalk, if all goes according to plan.

NASA astronauts Christina Koch and Jessica Meir had been scheduled to venture outside the International Space Station (ISS) together next Monday (Oct. 21), as part of a series of excursions to install new batteries. But they've been retasked and fast-tracked, thanks to the failure of one of the orbiting lab's power controllers over the weekend, NASA officials announced today (Oct. 15).

"@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 via Twitter . More details will be relayed during a press conference later today, he added.

Related: The Most Memorable Spacewalks in History

.@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. We’ll have a telecon later today. More details: https://t.co/0T6OOfuQQc pic.twitter.com/zQ7cH4fIBgOctober 15, 2019

The power glitch is a repeat of an issue that occurred in April after a battery-pack swap, NASA officials said during a press conference today. The failed battery charge/discharge unit (BCDU) will come back to Earth a few months from now aboard a SpaceX Dragon cargo capsule, and engineers will inspect the hardware to try to figure out what happened, they added. (The BCDU that failed in April is already on Earth, and researchers will compare the two units to see if the same issue afflicted both of them.)

Just 15 women have ever conducted a spacewalk , and all of them did so with a male companion. So Koch and Meir will make some long-overdue history.

And speaking of overdue: The all-female milestone was originally scheduled for March, and was to involve Koch and NASA astronaut Anne McClain. But that spacewalk was scuttled because properly fitted spacesuits could not be readied in time for both astronauts.

McClain, who came back to Earth in June, had kind words for Koch, Meir and their colleagues aboard the orbiting lab.

"Third spacewalk in a busy season of spacewalks this week. Date is unknown bc the task was unforeseen: replacing a unit that failed during power-ups of new batteries. Very good that we have 4 expert spacewalkers on board to shoulder this tough task. They are the A-team!" McClain said via Twitter today .

Six people are serving on the space station's current Expedition 61: Koch, Meir, and fellow NASA astronaut Andrew Morgan; Russian cosmonauts Aleksandr Skvortsov and Oleg Skripochka; and the European Space Agency's Luca Parmitano, who commands the mission.

Third spacewalk in a busy season of spacewalks this week. Date is unknown bc the task was unforeseen: replacing a unit that failed during power-ups of new batteries. Very good that we have 4 expert spacewalkers on board to shoulder this tough task. They are the A-team! https://t.co/pJKrOGbBbeOctober 15, 2019

Editor's note: This story was updated at 5:15 p.m. EDT to incorporate information from a NASA press conference.

Space.com associate editor Hanneke Weitering contributed to this story.