CAPE CANAVERAL, Fla. — A former space shuttle commander whose twin brother is married to former representative Gabrielle Giffords will attempt the longest space flight by an American.

NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko will spend a year aboard the International Space Station beginning in 2015.

Both countries’ space agencies announced the names of the 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. NASA wanted experienced space station astronauts to streamline the amount of training necessary for a one-year stint.

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

The longest an American lived at the space station was seven months, several years back.

A Russian, Valery Polyakov, logged nearly 15 continuous months aboard the old Mir space station in the mid-1990s.