NASA has pulled its first ever all-female space walk because of issues with the spacesuit sizes.
Anne McClain and Christina Koch were scheduled to install powerful lithium-ion batteries at the International Space Station (ISS) on Friday, but these plans will no longer go ahead.
It would have been a first-of-its-kind mission, as in the past astronaut pairings were all male or male-female.
But the US space agency says a shortage of correctly-fitting outerwear at ISS means the mission had to be changed.
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According to a press release issued on Monday, McClain had realised "during her first spacewalk that a medium-size hard upper torso - essentially the shirt of the spacesuit - fits her best".
The astronaut has trained in both medium and large spacesuits in the past. But only one medium-sized torso will be ready for use on Friday, and it will go to Koch instead.
"Because only one medium-size torso can be made ready by Friday, 29 March, Koch will wear it," NASA explained further.
NASA says Koch will now complete the spacewalk with her male colleague, Nick Hague.
The space agency later noted that it has two medium-size hard upper torsos at the ISS, but one of these needs to be properly configured for a spacewalk.
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This would apparently have taken too long to fix before Friday's spacewalk, so NASA instead made the decision to switch the astronauts instead.
It is difficult to fit astronauts with spacesuits because microgravity in space causes them to change size.
Agency officials were keen to stress that Koch and McClain were not deliberately teamed up Koch and McClain for the mission when it was first announced, but it was said that it would be a "proud" moment for NASA.
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"Anne and Christina will have the opportunity to be the first all-female EVA, which I think will be a proud moment for NASA, if the assignments stay as they planned,"said Mary Lawrence, a NASA spacewalk flight director at a press conference earlier this month.
"If they inspire that next generation of space explorers, they're certainly worthy of that inspiration, and I'm just really proud to be a part of it."
Women make up just 11 per cent of people in space. In the last 60 years of space flight, only four missions included two female members who were trained for spacewalks.
Topics: Life News, News, Nasa, space