9:53 AM PT -- NASA has just responded to the backlash, stating, "To clarify, we have more than 1 medium size spacesuit torso aboard, but to stay on schedule with @Space_Station upgrades, it's safer & faster to change spacewalker assignments than reconfigure spacesuits."

9:25 AM PT -- Hillary Clinton just weighed in on the situation, and her solution is pretty clear ... "Make another suit."

NASA's no better than your average department store -- lack of the right sizes in its women's department just screwed 2 astronauts out of making history with the first all-female spacewalk mission.

Turns out the space geniuses don't have enough spacesuits to fit female astronauts Christina Koch and Anne McClain ... who were scheduled to make a repair to the International Space Station's solar panels on Friday. NASA says it only has one medium-sized space shirt, and it's going to Koch ... although it's kind of a hand-me-down.

McClain used it last week during a spacewalk, which is when she discovered the bad fit. She originally planned to wear a large, but found the medium more to her liking. Since McClain wore it last, Koch is getting the nod this week.

NASA and all the astronauts agree the proper fit is critical to mission success ... still sucks to miss out on history. Perhaps worst of all, a man's taking McClain's place Friday.

Yes, even at around 220 miles above Earth ... there's a glass ceiling.

Note to President Trump: More fitting rooms for Space Force, please.