NASA astronaut ScottKelly and Russian cosmonaut Mikhail Kornienko will spend an entire year aboard the International Space Station. The extended mission will help provide information about far-flung trips to asteroids and Mars.

A former space shuttle commander whose twin brother is married to former Rep. Gabrielle Giffords will attempt the longest spaceflight ever by an American.

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NASA astronaut ScottKelly and Russian cosmonaut Mikhail Kornienko will spend an entire year aboard the International Space Station beginning in 2015.

Both countries' space agencies announced the names of the two veteran spacefliers on Monday. The extended mission was approved almost two months ago to provide a medical foundation for future missions around the moon, as well as far-flung trips to asteroids and Mars.

Both men already have lived aboard the space station for six months. NASA wanted experienced space station astronauts to streamline the amount of training necessary for a one-year stint. Officials had said the list of candidates was very short. They will begin training next year.

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"Their skills and previous experience aboard the space station align with the mission's requirements," Bill Gerstenmaier, head of human exploration for NASA, said in a statement. "The one-year increment will expand the bounds of how we live and work in space and will increase our knowledge regarding the effects of microgravity on humans as we prepare for future missions beyond low-Earth orbit."

Kelly's identical twin brother, Mark Kelly, retired from the astronaut corps last year and moved to Tucson, Ariz., his wife's hometown. The former congresswoman was critically wounded in an assassination attempt in January 2011, while ScottKelly was living aboard the space station.

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