Two women astronauts were set to make history at the very end of Women’s History Month: They were going to conduct NASA’s first-ever all-female spacewalk Friday.

But that monumental moment will not happen as scheduled, the agency said, because there are not enough spacesuits to fit the female astronauts.

Astronauts Anne McClain and Christina Koch had planned to install batteries outside the International Space Station.

NASA spokeswoman Stephanie Schierholz said in an email Tuesday to The Washington Post that both women now need a medium-sized hard upper torso — the shirt of the spacesuit — and there is only one medium-sized suit on the space station that is ready for use. NASA said astronauts Nick Hague and McClain completed the first spacewalk in the series earlier this month, so Hague and Koch plan to set out on the next one later this week.

Still, Schierholz said, “We believe an all-female spacewalk is inevitable.”

Both McClain and Koch were members of NASA’s 2013 astronaut class, 50 percent of which was made up of women, NASA said.

The women who were set to make history

McClain, a U.S. Army officer and a pilot, “wanted to be an astronaut from the time I was 3 or 4 years old,” she said in a 2015 NASA video interview. “I remember telling my mom at that time, and I never deviated from what I wanted to be. Something about exploration has fascinated me from a young age.”

McClain is currently aboard the ISS, where she is accompanied by an adorable Earth plush toy.

Koch, an electrical engineer, is taking her first space flight, according to NASA. Space is just the latest exciting frontier Koch has conquered: Her work has taken her on expeditions to the South Pole and the Arctic.

When asked in a February interview about the importance of conducting her mission during Women’s History Month, she said:

“It is a unique opportunity, and I hope that I’m be able to inspire folks that might be watching.”

Noting she did not have many engineers to look up to growing up in Jacksonville, N.C., she added, “I hope that I can be an example to people that might not have someone to look at as a mentor … that it doesn’t matter where you come from or what examples there might be around you, you can actually achieve whatever you’re passionate about.”

“If that’s a role that I can serve,” she said, “it would be my honor to do that.”

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