Yes, you get taller in space. No, not that tall.
Astronauts are known to ‘grow’ in orbit, and NASA is trying to better predict just how much
Space station astronaut Norishige Kanai’s exclamation last month that he grew 3.5 inches in space was a miscalculation but a small amount of growth in space is not a new concept to NASA.
In fact, the space agency has been studying this phenomenon for decades, most recently from 2013 to 2017 with nine astronauts aboard the International Space Station (Kanai was not one of them).
“Spinal elongation occurs due to the effect of weightlessness while orbiting, resulting in a reduced compression on the spinal column,” said Sudhakar Rajulu, Ph.D., with Johnson Space Center’s Human Health and Performance Directorate, who conducted the most recent study. “This allows for the straightening of the natural spinal curve.”
This happens with all genders and ages (the amount varies and can be up to 3 inches), Rajulu added, but it could cause problems for future, deep space travel.
Rajulu said its possible that astronauts may not be able to fit in their space suits if their height changes significantly, for example, or in their seat during re-entry on the Soyuz (a Russian spacecraft that transports astronauts to and from the space station) or, eventually, Orion (the spacecraft being built to transport astronauts to deep space).
This is exactly what Kanai was worried about when he tweeted last month about a growth of 9 centimeters, or 3.5 inches.
“In only three weeks I’ve really shot up, something I haven’t seen since high school,” he tweeted Jan. 8. “This makes me a little worried that I might not be able to fit in the Soyuz seats for our return.”
The next day, he corrected himself, saying that he measured again and found that he’d only stretched two centimeters, or .7 inches, from his original height. He did not explain how he made the miscalculation.
“It appears I can fit on the Soyuz, so I’m relieved,” he tweeted Jan. 9.
NASA scientists studied height changes for astronauts both on Skylab in the 1970s and the Space Shuttle from 2009 to 2011 before its most recent experiment. After the Skylab study, NASA recommended that a 3 percent change in height be anticipated. They got even more specific after the Space Shuttle study, concluding that crewmembers would experience roughly a 6 percent increase in their seated height, with a corresponding 3 percent increase in stature.
But those studies only examined a body’s stature and seated height changes. Rajulu’s study examined overall body shape and size changes, including stature, circumference, chest width and arm and leg length.
Data from Rajulu’s study still is being analyzed, which likely will take three months, he added.
He hopes the study’s findings help NASA develop a model that can predict changes in height and body shape.
It’s important, he said, so NASA can make plans for these changes as deep space travel becomes more of a reality.
“The projections of seated height will provide data on the proper positioning of the seats within the vehicle, adequate clearance for seat stroke in high acceleration impacts, fit in seats, correct placements of seats with respect to each other and the vehicle and the proper orientation to displays and controls,” a June post on NASA’s website stated.
“Additionally,” the space agency said, “data concerning the effects of spinal elongation on seated height would aid in the design of suit components, habitation requirements and tool specifications of future long-duration space expeditions.”