Something bizarre happens to your feet when you spend months in space
They usually wear socks, with thick Polartec socks layered on top if they get cold.
But Astronaut Scott Kelly, who's spent almost a year in space, said in a Reddit AMA that this made something rather odd happen to his feet.
"The calluses on your feet in space will eventually fall off," he wrote. "So, the bottoms of your feet become very soft like newborn baby feet. But the top of my feet develop rough alligator skin because I use the top of my feet to get around here on space station when using foot rails."
Kelly also said in a Q&A on Tumblr that this foot phenomenon was the "weirdest thing" that had happened to him on the ISS.
Astronauts on the International Space Station (ISS) use foot rails and loops to help hold them steady when they have to do an experiment, or just get a haircut.
Astronauts typically only change their socks and underwear every other day, and their shirts and pants every 10 days, according to NASA, since they don't get as dirty in space as we do here on earth.
Astronaut Don Pettit, who's logged over 300 days in space, said the same thing happened to his feet in a 2012 blog post.
"After about two months in orbit your feet molt, and like some reptilian creature the callused skin on the bottom of your foot sheds, leaving soft pink flesh in its place," he wrote. "In the weightless environment, calluses apparently have no use, at least on the bottoms of your feet. However, the tops of your feet become red-rubbed raw and gnarly. And the bottom calluses shed faster than the top calluses can grow. Perpetually raw and hypersensitive, your foot tops can use a bit of padding to ease the pain."
He accidentally grabbed a pair of small women's socks one day that only covered the top half of his foot, but they perfectly protected the part that needed it.
"They are the zero-gravity equivalent to flip-flops," he wrote.