CAPE CANAVERAL, Fla. (AP) — NASA astronaut Scott Kelly is already bracing for an unprecedented one-year mission aboard the International Space Station. He figures it will be as grueling as climbing Mount Everest.

"It's fun when you're done with it, not while you're doing it," Kelly said Wednesday, barely a week after being named to the marathon flight along with Russian cosmonaut Mikhail Kornienko.

The mission, set to begin in 2015, is intended as a medical test bed for even longer Mars expeditions in the decades ahead.