NASA officials didn't realize until after they had scheduled it that a Friday mission involving American astronauts Anne McClain and Christina Koch would be the first all-women spacewalk. But the milestone has now been called off because of a lack of medium-sized spacesuits, the New York Times reports. NASA said in a press release Monday that the assignment to install lithium-ion batteries for the International Space Station's energy system was adjusted because of spacesuit availability. There is only one medium-sized hard upper torso currently available, NASA said. Koch uses a medium, and while McClain thought she would work in a large size, she wore the medium during a spacewalk last week and discovered it fits her better.
Wearing an ill-fitting spacesuit is risky, NASA says, and it would take hours of work to configure the other medium-size torso for a spacewalk. "Individuals’ sizing needs may change when they are on orbit, in response to the changes living in microgravity can bring about in a body," NASA spokeswoman Brandi Dean tells Quartz. Koch will now carry out the mission with another astronaut. "When you have the option of just switching the people, the mission becomes more important than a cool milestone," NASA spokeswoman Stephanie Schierholz tells the Times. But she adds that since a growing proportion of NASA astronauts are women, "we're sort of getting to the point of inevitability" for an all-female spacewalk. (Read more spacewalk stories.)