It's pretty remarkable to have one astronaut in a family. But having two? Who happen to be identical twins? And will be in space together at the same time?
Well, the stars have to be aligned for that to happen.
Scott Kelly lifted off Thursday U.S. time from Kazakhstan aboard a Russian Soyuz on a six-month mission to the International Space Station. His brother, Mark, is scheduled to command Endeavour on its last shuttle mission at the end of February.
If Endeavour's launch date holds, that will mark the first time that siblings are in space together, NASA officials said.
"It's something that . . . I think we both consider would be really neat if it happened, but just having the privilege of flying in space, without flying together is just an incredible opportunity," Scott said. "I always thought it'd be great if it happened but if it didn't, you know, I have no control over that."
The brothers, 46, are slated to spend eight days together on the space station.
"We have never had siblings in space before, so not only is it unusual, it is a first," said Nicole Cloutier-Lemasters, NASA spokeswoman.
Both men are veteran astronauts and have been shuttle commanders and pilots. Scott's flight is his third trip in orbit.
Endeavour will be Mark's fourth flight. It's the same shuttle that took him to space for the first time in 2001.
Growing up in New Jersey, the brothers said they never dreamed about becoming astronauts, let alone the only sibling astronauts for NASA. It wasn't until they were in college, at separate schools, that being a space man became a reality.
Both enlisted in the Navy and eventually became captains.
When Mark interviewed for the Astronaut Corps he borrowed his brother's new business suit. One month later, Scott wore the same suit for his astronaut interview, along with his brother's shoes.
The attire seemed to work. Both were selected in 1996 into the same class.
There was no sibling rivalry when Scott was the first one selected for a shuttle flight in 1999.
"He was the first American in our class to fly of 35 so it was great that, you know, if it wasn't going to be me, it was great that it was Scott flying for the first time," Mark said.
The brothers concede the camaraderie wasn't always there.
"Pretty much every day we would get into fist fights so it was, it was tough for my mom," Mark said about their childhood. "She'd try to break 'em up, you know, and then some of these fights would last hours and hours."
Scott cheered for the New York Mets, so Mark said he naturally was a fan of the rival Yankees.
However, they did have their similarities. They shared a few high school classes and were co-captains of their high school swim team.
Although they got plenty of pressure in high school to use their identical looks to pull a prank, the brothers said they never gave in.
"I think we were saving up for the big prank some day and we have the perfect opportunity now," Scott said jokingly.
But don't expect it to happen when the brothers are together on the space station.
Both said it's all business up there.
Mark will be delivering supplies to the station and Scott will serve as a flight engineer and commander during his six-month-long mission.
"Scott and I have to work together to make sure this thing gets executed correctly with nobody getting hurt and everything getting accomplished so it's really going to be more about the mission than 'Hey, we're in space together,"" Mark said.
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