RACHEL MARTIN, HOST:
OK. Have you ever wondered what happens physically to people when they're in outer space? Like, what actually happens to their bodies? Scientists have shared results from NASA's twin study.
DAVID GREENE, HOST:
Yeah, for nearly a year, Scott Kelly lived at the International Space Station. Scientists compared samples from him and his earthbound twin brother, Mark.
MARTIN: I talked with Scott Kelly back in 2017, and I asked him about his health.
(SOUNDBITE OF ARCHIVED BROADCAST)
SCOTT KELLY: You know, the symptomatic stuff is fine. I don't have any long-term negative feelings, physically, from being in space. Now, there's the things you can't feel. And hopefully, I will never learn that those are a problem.
GREENE: Those things you can't feel - well, it turns out they are as small as the protective structures at the ends of his chromosomes.
MARTIN: Yeah. These are called telomeres, and normally, they get shorter with age. But what about in space?
SUSAN BAILEY: What we wanted to do was evaluate telomere length in both of the twins before and after so that we could see, you know, where they started and then where they ended.
MARTIN: Susan Bailey was one of the scientists who answered this question. She expected the stresses of space to shorten telomeres quicker.
BAILEY: And, in fact, we saw exactly the opposite thing - that during spaceflight, he had many more long telomeres than he did before he went up. So that really couldn't have been more of a surprise to us.
GREENE: All right. Some other findings - Scott Kelly's gene expression changed, and his immune system went into high alert. His flu shot worked despite all the stress of space. Back on Earth, his body returned to normal within months.
MARTIN: Andrew Feinberg, another scientist who led part of this study, said this is a new chapter in tracking the effects of spaceflight.
ANDREW FEINBERG: I think that this study represents the dawn of the era of human genomics in space.
MARTIN: And the human body, or at least Scott Kelly's, seems pretty resilient.
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