2 astronauts to spend year in orbit INTERNATIONAL SPACE STATION

This photo combo provided by the Gagarin Cosmonaut Training Center via NASA, shows NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko. Kelly and Kornienko will spend an entire year aboard the International Space Station beginning in 2015, according to reports, Monday, Nov. 26, 2012. 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. (AP Photo/Gagarin Cosmonaut Training Center via NASA) less This photo combo provided by the Gagarin Cosmonaut Training Center via NASA, shows NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko. Kelly and Kornienko will spend an entire year aboard the ... more Photo: Associated Press Photo: Associated Press Image 1 of / 1 Caption Close 2 astronauts to spend year in orbit 1 / 1 Back to Gallery

Cape Canaveral --

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

NASA astronaut Scott Kelly 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 space fliers 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 and will begin training next year. NASA said it would outline the mission in news conferences next week.

"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," Bill Gerstenmaier, head of human exploration for NASA, said in a statement.

Astronauts normally spend about four to six months aboard the space station.

Kelly's identical twin brother, Mark Kelly, was living aboard the space station when Giffords was critically wounded in an assassination attempt in January 2011. Mark Kelly has since retired from the astronaut corps.

Boris Morukov, head of Moscow's Institute for Medical and Biological Problems, Russia's main space medicine research center, told the Interfax news agency that communications and food rations for Kelly and Kornienko may be limited during their yearlong mission to better simulate interplanetary travel.

Kelly and Kornienko will launch aboard a Russian rocket from Kazakhstan. Americans must buy seats on Russian spacecraft now that NASA's shuttles have retired to museums, until private U.S. companies have vessels capable of carrying human passengers. That's still four or five years off.

Kelly is a 48-year-old, divorced Navy captain with two daughters. Kornienko, 52, a rocket engineer, is married with a daughter.