Former U.S. space shuttle pilot and station commander Scott Kelly, who last flew in 2011, will be paired with Russian cosmonaut Mikhail Kornienko for a 12-month space station assignment beginning in early 2015.

"Life on the space station is pretty routine, you know. In the morning you wake up, you are at work, when you go to sleep you are also at work. So imagine being in your office a whole year and you never get to leave. That is a challenge and it presents its own set of issues but I think I am up for it and I look forward to it," said Kelly.

Cosmonaut Mikhail Kornienko served as a flight engineer aboard the station in 2010.

Only four people have lived off-planet for a year or longer.

Most stints on the ISS, a $100 billion, permanently staffed laboratory orbiting 250 miles above Earth, have lasted no more than six months.

With the retirement of the space shuttles last year, NASA is working on a new space transportation system that can fly astronauts to the moon, asteroids and other destinations in deep space.

The goal is to send a crew to Mars in the mid-2030s.

Kelly and Kornienko are scheduled to begin a two-year training program early next year.