Here's why astronauts' bodies struggle to re-adapt to Earth's gravity
NASA astronauts Sunita Williams and Butch Wilmore have finally returned to Earth after being stranded in space for nine months.
The pair was originally set for an eight-day International Space Station mission for the launch of Boeing’s new Starliner crew capsule in June but got stuck for months due to technical issues with their spacecraft.
Williams and Wilmore splashed off the Florida coast on Tuesday, March 18. They were later disembarked from the spacecraft and loaded onto stretchers.
You may wonder: why were they carried on stretchers? Experts told educational outlet Live Science that this procedure is a protocol all astronauts must follow. Astronauts who spent significant time in space—where there is no gravity—have experienced body changes, which makes them unable to immediately walk upon return to Earth, among other effects.
"A lot of them don't want to be brought out on a stretcher, but they're told they have to be," John DeWitt, director of applied sports science at Rice University in Texas and a former senior scientist at NASA's Johnson Space Center, told the outlet.
In January, Williams shared with students what it’s like living without gravity.
"I've been up here long enough right now I've been trying to remember what it's like to walk. I haven't walked. I haven't sat down. I haven't laid down. You don't have to. You can just close your eyes and float where you are right here," Williams said.
According to NASA, when in space, transitioning from one gravity field to another is “tricky” as it affects “spatial orientation, head-eye and hand-eye coordination, balance, and locomotion,” which leaves some crew members experiencing space motion sickness.
The body may experience post-flight orthostatic intolerance or the inability to maintain its blood pressure, which may cause lightheadedness and fainting.
“NASA has learned that without Earth’s gravity affecting the human body, weight-bearing bones lose on average 1% to 1.5% of mineral density per month during spaceflight,” it said. Upon return to Earth, bone loss might not be completely corrected by rehabilitation.
Alan Duffy, an astrophysicist at Swinburne University, told The Guardian that fluids shifting in the body upwards make them “feel like they have a constant cold” in microgravity. The built-up fluid may also put pressure and change the shape of the eyeballs.
Upon return to Earth, Duffy said that they will struggle to walk, become dizzy, and have vision problems—which may be permanent.
Duffy also noted that astronauts may feel “almost baby-like sensitivity” on the skin after spending significant time with clothing floating off the skin. He added that some astronauts “feel like their clothing is sandpaper” once they return to Earth.
Meanwhile, NASA detailed other body complications caused by these changes.
“If preventive or countermeasures are not implemented, crews may experience an increased risk of developing kidney stones due to dehydration and increased excretion of calcium from their bones,” the agency said.
Wilmore and Williams are part of the Crew-9 mission alongside NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbu. The duo’s 286-day stay ranked them sixth in US records for single-mission duration. The current record holder is Frank Rubio who spent 371 days in space.
