Though Scott Kelly has been back on Earth for some time, researchers are still collecting and sifting through data from him and his twin brother, Mark, the Verge reports.
The brothers are taking part in the NASA Twin study, in which samples were collected from Scott before, during, and after his year in space as well as from Mark, who stayed behind on Earth. So far, researchers have found that Scott's telomeres unexpectedly lengthened while in space, as compared to Mark's. "The presumption was that in the radiation — there's a lot of radiation in space — and the stress of being on the space station, they thought that those things would result in the shortening of his telomeres," Mark Kelly tells the Verge.
The NASA study also found that Scott's gut microbiome changed while in space, a finding that Scott says was expected because of the unusual environment he was in.
The Kellys say that being a test subject is part of the life of an astronaut. "I just think it's part of the responsibility when you're in this very unique position, to participate in these studies and be a human subject. So it's not even something I think about, actually," Scott Kelly tells the Verge.