The first-ever all-women spacewalk originally scheduled for Friday will no longer be all women. Late Monday afternoon, NASA announced a change in its spacewalk scheduling, revealing that astronaut Anne McClain would be replaced by Nick Hague for Friday’s operation.

Originally, McClain and Christina Koch were set to follow-up on an earlier spacewalk that took place March 22. They planned to continue work behind the installation of lithium-ion batteries for a pair of the International Space Station’s solar arrays. This would have been the first time a crew of only women conducted a spacewalk.

So what happened? NASA’s statement, along with comments given to Popular Science by a NASA spokesperson, noted that there were issues involved in the availability of spacesuits on the ISS. Spacesuits are reconfigurable in different ways, being that each is comprised of a top and a bottom. McClain had trained in both the medium and large torso parts, but learned during her March 22 spacewalk that she fits better in a medium-size torso. So does Koch.

And while there are actually two medium size spacesuit segments on the station, it’s much easier and faster to simply change out who’s going than reconfigure the entire spacesuit, especially if the agency is trying to avoid schedule delays that disrupt plans down the line. So NASA elected to have Koch wear the suit for the March 29 spacewalk (and move Hague into the open slot for that operation), and have McClain wear it on the spacewalk scheduled for April 8.

“We do our best to anticipate the spacesuit sizes that each astronaut will need, based on the spacesuit size they wore in training on the ground, and in some cases (including Anne’s) astronauts train in multiple sizes,” NASA spokesperson Brandi Dean told Popular Science. “However, individuals’ sizing needs may change when they are on orbit, in response to the changes living in microgravity can bring about in a body.” For instance, McClain herself tweeted earlier this month that the microgravity environment in orbit had caused her to grow two inches taller (a common occurrence, as the disks of fluid between human vertebrae expand without the crush of gravity).

“No one training environment can fully simulate performing a spacewalk in microgravity,” said Dean, “and an individual may find that their sizing preferences change in space.”

While it is encouraging to know that McClain and her fellow crew members are empowered to make decisions on their preferences for these operations, many have speculated that NASA’s decision was a symptom of flawed, biased logistics that hadn’t taken typical female sizes into account—hence there being only one medium-sized torso at-the-ready instead of two. Even Hillary Clinton has weighed in.

Gender bias is absolutely a systemic problem in space and every STEAM discipline, but it’s also important to note that in this particular instance, there are a lot of other factors at play—including the fact that NASA basically has a spacesuit crisis on its hands. Hugo Award-winning author Mary Robinette Kowal posted a very good tweet thread Tuesday afternoon emphasizing that the spacesuits, originally designed more than 40 years ago, were meant to have only a 15-year lifespan and be refurbished periodically to mitigate and repair wear and tear. Only four of the original 18 are aboard the ISS. “When NASA says there’s not one readily available, it’s sort of like…yeah. There’s one up there, but we aren’t sure it won’t leak,” Kowal wrote.

To that end, it makes sense that the agency would just move Hague into Friday’s spacewalk and have McClain slotted for the following week—safety and comfort are of the utmost priority. It’s already hell to put on a space suit and venture out into a cold empty vacuum hundreds of miles above Earth. A suit with the snuggest possible fit gives you more control of your own movements, as well as the ability to properly interface with some of the suit controls. If we had more spacesuits, and ones in smaller sizes, it’s possible all of this could have been avoided. And if NASA had been more inclusive toward women since its inception, perhaps we would have had them. Kowal’s Twitter thread noted that when NASA nixed its small and XL suit sizes due to budget cuts, “many of the male astronauts could not fit into the L suits, so the XLs were brought back.” But the smallest suits weren’t.

Monday’s schedule change is not any one person’s fault. But the disappointing turn of events reinforces how long the effects of past decisions can last. NASA and the space community at large are making inclusivity of women a bigger priority than ever, but in many ways, we’re still trying to undo biases taken for granted decades ago.