Last month, when the crew of NASA’s SpaceX Crew-8 International Space Station crew finally returned from a mission that was extended from 180 days to 235 days, the splashdown and recovery were initially described as safe and apparently uneventful.
Then, hours later, NASA announced that all four of members of the crew—NASA astronauts Matthew Dominick, Michael Barratt, and Jeanette Epps, and Roscosmos cosmonaut Alexander Grebenkin—had been whisked off to a nearby medical facility for “additional evaluation” following their standard post-flight medical checks.
Initially, the agency said this was done “out of an abundance of caution,” but it was then revealed that one of the astronauts was hospitalized, although this was again described as a “precautionary measure.”
Since then, NASA has refused additional information, including the name of the hospitalized astronaut.
Two weeks later, in a news conference last week, Barratt, who was both the pilot and an M.D., admitted that this silence might have produced “some interest” in “our post-flight medical event.”
“Space flight is still something we don’t fully understand,” he said. “We’re finding things that we don’t expect sometimes. This was one of those times, and we’re still piecing things together.”
Despite repeated questioning from reporters, that was all that he, or anyone else, would say about precisely what happened. “For now,” he said, “medical privacy is very important to us.”
What he and others were willing to talk about were the basics of how months in space affects the human body, and how critical it is to learn about these things before we attempt a mission to Mars, which by necessity involves six months in space, each direction.
The big issues of course, involve important ways of not-dying, such as maintaining life support and not crash-landing, as well as providing radiation protection in case a dangerous solar storm catches them midway through their flight.
Nearly as high on the list are maintaining bone density, muscle mass, aerobic capacity, and immune function—each of which can be severely affected by months of inactivity. But these losses, Barratt says, can be offset by what he calls “countermeasures”—basically zero-gee gym equipment that appears to be able to delay them for at least long enough to get to Mars.
But there are a host of other potential problems, some of which can occur much more quickly.
One is fluid shift, says Rihana Bokhari, acting chief science officer at the Translational Research Institute for Space Health at Baylor College of Medicine in Houston, Texas.
In space, gravity isn’t pulling fluid downwards, towards the legs. That causes it to be redistributed more evenly around the body. “While an astronaut is in space, this does not really cause issues, other than astronauts looking a bit ‘puffy,’” she says. But when they come back to Earth, gravity will again exert its normal effect. “This can lead to difficulty maintaining arterial blood pressure and can lead to dizziness, fainting, and [other issues],” she says.
Another issue is “sensorimotor” changes. These, Bokhari says, refer to how our inner ears, vision, and sense of body position help us understand how we are positioned in three-dimensional space. “In microgravity, it takes time for the body to understand the new inputs and the change in sensing things like up and down,” she says.
In space, she says, adapting to this can produce nausea and space motion sickness. Once back on Earth, it can produce the reverse problem, including balance problems and difficulty walking in a straight line.
Not that this is likely to be what affected all four of the Crew-8 astronauts. But it is a concern for a potential Mars-bound crew in the future.
“When astronauts return to Earth, they are greeted by a team that helps them exit the vehicle safely,” Bokhari says. “Without a team to intervene on the first trips to Mars, a broken bone could be a serious and potentially life-threatening situation.”
Meanwhile, NASA is promising a better explanation of what happened on 25 October. “I’m a medical doctor,” Barratt says. “Space medicine is my passion. In the fullness of time, we will allow this this to come out, and document it.”
Meanwhile, he says, “expect the road to Mars to be paved with new [medical] discoveries, whether we like it or not.”
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