Now that they have spacesuits that fit, two female astronauts will make history by going on an all-female spacewalk. NASA astronauts Christina Koch and Jessica Meir are scheduled to take a walk outside the International Space Station on Oct. 21, NASA announced.

Koch was originally scheduled to conduct a spacewalk with her then-crewmate, Anne McClain, on March 29, following another spacewalk featuring McClain and NASA astronaut Nick Hague on March 22. However, mission managers decided to change assignments, NASA explained, "due in part to spacesuit availability on the station."

McClain realized her best fit was a medium-sized hard upper torso — "essentially the shirt of the spacesuit," according to NASA. But there was only one available in time for the spacewalk, so Koch wore it and Hague filled in for McClain.

"It is more efficient to swap spacewalkers than to reconfigure the elements of the spacesuit," NASA spokeswoman Stephanie Schierholz told NBC News, noting the fit of a spacesuit can affect an astronaut's ability to maneuver and perform tasks.

But now the suits and the astronauts are ready. Another medium size suit was launched to the ISS earlier this year, according to Kirk Shireman, NASA’s program manager for the ISS, the Verge reports.

“We don’t do it for a specific crew member,” Shireman said during a press conference in early October. “Actually, what we do is we look over the next two years, and look at all the crew members who are [spacewalk] certified, and say, ‘OK, what’s the sweet spot?’” Shireman pointed out that over the next couple of years, a lot of “medium suit people” will be heading to the ISS.

Koch talked about how their accomplishments are viewed in terms of being female astronauts.

In July 1984, cosmonaut Svetlana Savitskaya became the first woman to walk in space. Thirty-five years after that historic occasion, two women will conduct the first all-female spacewalk.

Spacewalks are conducted for a range of reasons, from performing experiments outside of the International Space Station to testing and repairing equipment.

Editor's note: This story has been updated with new information since it was originally published in March 2019.

NASA's all-female spacewalk is back on
NASA astronauts will make history on an all-female spacewalk now that the spacesuit problem is resolved.