(CNN) – After more than nine months in space, Commander Suni Williams and Captain Butch Wilmore are home safe and sound.
Now their bodies must readjust to life on Earth after going 286 days without feeling its gravitational pull.
“Gravity is really, really tough,” Wilmore said.
It’s tough learning to live with gravity when you’ve learned to live without it.
“Our bodies were really built to work in gravity,” biochemist John DeWitt said.
At NASA’s countermeasures lab, exercise routines and equipment are designed to help prevent astronauts from losing bone and muscle mass while they’re in space.
“Force is what helps our muscles get stronger. Force is what helps our bones to stay strong. Force is what helps our heart to stay strong by having to pump the blood against gravity,” DeWitt said. “So, when you take that force away, you all of a sudden lose a really important stimulus that’s important for health.
It would be the same thing as if someone was confined to a bed because they had an injury for a long time. People lose their muscle strength. They lose their bone strength.”
That’s why astronauts spend hours each day exercising while on the space station.
Williams even showed CNN’s Dr. Sanjay Gupta in 2012 how she was preparing to do a triathlon from space so that she could compete with him while he was doing a triathlon on Earth.
“I’ll be done like that. What am I saying? I’ll be, I’ll be done way before you,” she said.
But again, space is an unnatural environment for humans.
As much as two liters of body fluid shift from the legs to the head and upper body when someone is in space. NASA says a natural reaction to this is a decrease in the total amount of blood in blood vessels, which can result in low blood pressure or hypotension.
It is also shown that the brain shifts up ever so slightly in the skull and the fluid surrounding and protecting it expands.
“To have, you know, me being there for such a long time they can see how that, you know, environmental effects affect us on a genetic level and what that means to our health,” astronaut Scott Kelly said.
Kelly knows this better than most people.
He spent 340 days aboard the International Space Station for NASA’s twin study, where they compared his physical state in space to his twin brother Mark Kelly back on Earth.
They found that space impacted a host of things like his eyes, his balance, his gut microbes, his cognitive abilities, and even his gene expression.
Then, when the body is thrust back to Earth, it has to adapt again.
“When you get back, gravity starts pulling everything to your lower extremities, the fluid that is shifting, you know, I got a little puffy face,” Wilmore said. “It’s always that way when I’m in space … it’s really going to be different. Even to lift a pencil, you don’t even feel a pencil when you lift it. When we get back, even to lift a pencil, we will feel the weight.”
And it will take time to adjust.
In fact, when Kelly landed back on Earth in 2016, he was actually two inches taller, but then, as gravity took hold, his height, along with most of the other physical changes, did eventually go back to baseline.
It took about six months, with the study concluding that human health can be mostly sustained for a year in space.
Kelly did, however, find some benefits.
“When I got back on my previous flight, and, I was getting a massage at one of these Massage Envy places. The lady goes, she goes, you have the softest feet I’ve ever felt in my life, and she did not know I was in space,” Kelly said. “And I was like, ‘Thank you. I’m very proud of them.’”
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