This segment originally aired on April 27, 2014.
SCOTT KELLY: I listened to that in space when I was exercising - ALL THINGS CONSIDERED.
ARUN RATH, HOST:
That's astronaut Scott Kelly.
S. KELLY: Yeah, when I was doing the resistive - like the weightlifting it was good to, you know, to listen to NPR. Although I don't listen to NPR on Earth much just because I don't know what channel it's on.
RATH: Well, maybe Scott Kelly is listening again. Yesterday, he left Earth for a year-long mission at the International Space Station. While he's up there, he'll be part of some novel experiments involving his brother, Mark. Mark is also an astronaut, but will stay on Earth. And he's Scott's identical twin. The Kelly brothers spoke with my colleague Eric Westervelt shortly after Scott was picked for the mission.
ERIC WESTERVELT, BYLINE: Scott Kelly and Mark Kelly, welcome to the program, thanks for coming in.
S. KELLY: Well, it's great to be here.
MARK KELLY: Thank you.
WESTERVELT: It's tough on the radio - listeners can't really see you, but you guys are identical twins. What do you look like? Tell us, Mark, you go first.
M. KELLY: What do we look like? Well, I look like him and he looks like me - you know, two regular guys from New Jersey.
S. KELLY: That are about 50 years old.
WESTERVELT: Middle-aged guys.
M. KELLY: Well, you - you know, you could characterize it as that but, you know, 50 is the new 30, right? That's what people tell me.
WESTERVELT: Where did this idea come from - to test whether identical siblings remain the same if one's in space and the other's on the ground?
S. KELLY: When I was assigned to this flight, we were getting ready to announce it at a press conference. And I was given a briefing from the science people on the type of science we would be doing and looking at on this one-year flight. And I asked them if someone was to ask the question about doing some kind of comparative studies between my brother and I, considering that, I mean, it was kind of ironic or interesting, maybe serendipitous that after this flight, I will have flown about 540 days compared to his 54 or so - an order of magnitude more. And they came to the conclusion that there was merit in this and doing this type of investigation that is mostly based on our genetics and the effect on our genetics from long-duration spaceflight.
WESTERVELT: Mark, you'll be on the ground - you've arguably got the easier part of this. What will your day-to-day life be like in terms of these experiments while Scott's in space? Will you have to do daily, weekly monitoring and tests?
MARK KELLY: Well, as a NASA astronaut over, you know, a 15-year period, had a lot of science done on me already, so I kind of know what I'm getting myself into. Something might include doing a 24-hour urine sample, which means you're carrying a bucket around with you essentially.
WESTERVELT: That'll be interesting at barbecues.
M. KELLY: Yeah, yeah, it is. It's interesting at barbecues. The kids usually get, you know, a little laugh out of, you know, Dad's pee being in the refrigerator. So there are things like that, but I don't have a schedule yet.
WESTERVELT: Researchers, as I understand it, already know a little bit that the human immune system changes a lot in space. I mean, which of you do you think will be healthier at the end of the year? Scott?
S. KELLY: Good question. You know, there's a lot of impacts and effects on the human body due to long-duration spaceflight. You lose bone and muscle mass.
M. KELLY: Yeah, his bones are going to turn to dust in a year.
S. KELLY: And you get radiation that could, you know, increase your risk of fatal cancer over your lifetime. As far as overall health, you exercise a lot, so that's a plus. But you know, there's also those unknowns about your immune system, so it's - you know, that's what we're hoping to learn.
WESTERVELT: And are you guys going to be competitive about this at all? Like, Mark, maybe you'll exercise more and avoid a few cheeseburgers just to try to beat Scott?
M. KELLY: Well, yeah, maybe, you know, you never know. I mean, you know, he'll be working out twice a day, I think, for two hours a day, six days a week. So maybe it'll motivate me a little bit.
WESTERVELT: Scott Kelly and Mark Kelly - they're both astronauts, they're also identical twins. The brothers Kelly - thanks very much.
M. KELLY: Oh, you're welcome.
SCOTT KELLY: Yeah, thank you, my pleasure.
RATH: My colleague Eric Westervelt with Scott and Mark Kelly. Scott's year-long mission to the International Space Station began yesterday. Transcript provided by NPR, Copyright NPR.