Space changes you, even during short trips away from Earth.
The four people who spent three days away from Earth in September 2021 experienced physical and mental changes, including slight declines in cognitive tests, stressed immune systems and genetic changes in their cells, scientists reported in a series of papers published Tuesday in Nature and other related journals.
Most of the changes in the astronauts went back to normal after they splashed down on Earth, and none of the changes seem to pose any major warning signs for future astronauts. But the results highlight just how little medical researchers know.
Christopher Mason, a professor of genomics, physiology and biophysics at Weill Cornell Medical College in New York City and one of the study's leaders, called the paper and data collection “the most thorough investigation of the crew we've ever conducted,” during a press conference on Monday.
The four astronauts traveled on a mission called Inspiration 4, the first trip to orbit where none of the crew were professional astronauts. The mission was led by billionaire entrepreneur Jared Isaacman. Instead of taking a friend, he recruited three travelers who represented a broader social class: Hayley Arceneaux, a medical assistant who survived childhood cancer, Sian Proctor, a community college professor of geology, and Christopher Sembroski, an engineer.
The Inspiration 4 crew agreed to take part in medical experiments that would take blood, urine, feces, and saliva samples during the flight, and that the data would be catalogued in an online archive called the Space Omics and Medical Atlas (SOMA) and made available to the public.
The data is anonymous, but there isn't much privacy to be had with Inspiration 4's four-person crew. “We might actually be able to tell who's who,” Dr. Proctor said in an interview.
But, she added, “I feel like by me sharing information, and the science advancing and learning, it's doing more good than harm.”
SOMA also includes data from other people who have taken part in private space missions, as well as a Japanese astronaut who flew to the International Space Station, and a study comparing the health of NASA astronaut Scott Kelly, who spent 340 days aboard the International Space Station in 2015 and 2016, and his twin brother Mark, a retired astronaut who is now a senator from Arizona.
As more private citizens buy space travel, the hope is that SOMA will soon have information on a broader population than just the old white guys who were selected for astronaut duty in the early decades of the space age. That could allow for the development of tailored treatments to counter the effects of spaceflight.
The wealth of information also allows scientists to compare short-term effects with what would happen during a longer-term mission.
During Kelly's year in space, age markers in his DNA, called telomeres, lengthened — a surprising move that suggested he'd become biologically younger. But after he returned to Earth, most of his telomeres returned to their previous size, although some were shorter than they were before he left space. Scientists interpreted this as a sign of accelerated aging.
The telomeres of all four Inspiration 4 astronauts also lengthened and then shortened, indicating that the changes occurred in all of them, and that they occurred rapidly.
“This is a remarkable finding on many levels,” said Susan Bailey, a professor of radiation cancer biology and oncology at Colorado State University, who led the telomere study.
Cells use RNA, a single-stranded nucleic acid, to translate the blueprints coded in DNA into making proteins. Dr Bailey said the RNA equivalent to telomeres was also altered in astronauts, and similar changes had been observed in Everest climbers.
“It's a strange connection,” she said.
This suggests that it's not weightlessness that causes telomeres to shorten and grow, but rather the barrage of radiation that people experience at high altitudes and in space.
The impacts of spaceflight don't end there.
Afshin Beheshti of the Blue Marble Space Sciences Institute and NASA Ames Research Center in California said molecular changes in astronauts' kidneys could be a precursor to kidney stone formation — not a problem on a three-day spaceflight but a potential medical risk on longer missions.
“How are we going to treat them when we're halfway to Mars?” Dr. Beheshti said.
But now that this possibility is known, researchers may be able to investigate ways to prevent kidney stones or develop better treatments.
The astronauts took several tests on iPads to measure their cognitive performance in space. One test assessed psychomotor vigilance, the ability to focus and maintain attention on a task. The astronauts stared at a box on the screen, and suddenly a stopwatch appeared inside the box, counting the time it took for a button to be pressed.
Reactions that were too slow — more than 355 milliseconds — were deemed a lack of attention. On average, Inspiration 4 astronauts performed worse in space than when they took the same tests on Earth. Other tests showed deficits in visual search and working memory.
“Cognitive performance was not affected in space, but reactions to speed were slowed,” Arsenault said in an email. “This surprised me.”
But Proctor said it may not have been a real difference in their ability to carry out the mission in space, but simply a matter of being distracted. “It's not that they don't have the ability to do the test well,” he said. “You just kind of look up and you see the Earth out the window and you think, 'Wow.'”
One benefit of collecting all the data is that it allows scientists to look for connections between changes, something that was difficult for scientists to do with the narrower data sets they had before. “When you look at it as a whole, the pieces of the puzzle start to come together,” says Dr. Beheshti.
This could indicate a common cause, “so measures can be more targeted,” he said.
Since returning to Earth, life for some of the Inspiration 4 astronauts has in many ways returned to the way it was before they went into space. Ms. Arsenault is back to working 12-hour shifts as a physician assistant at St. Jude Children's Research Hospital in Memphis; Dr. Proctor remains a community college professor; and Ms. Sembroski, who lives near Seattle, now works as an engineer for Blue Origin, the rocket company owned by Jeff Bezos.
But Dr. Proctor is also now serving as a science envoy for the U.S. Department of State. This week she's visiting Peru and Chile to talk about her experiences in schools and universities. “I now have this kind of global platform where I can do work that helps inspire and prepare the next generation,” she said.
Arceneaux said he remembers looking down at Earth from the cupola window of SpaceX's Crew Dragon spacecraft on the second day of the trip.
“I feel so connected to my fellow Earthlings,” she said. “We are all one on this beautiful planet.”
Isaacman's time in space isn't over yet: He and three other civilian astronauts are scheduled to embark on a mission called Polaris Dawn, which could launch next month. During that flight, again aboard SpaceX's Crew Dragon spacecraft, Isaacman and another crew member will attempt the first private spacewalk.