Scientists reemerge after year 'on Mars'

(UPDATE) WASHINGTON — The NASA astronaut knocks loudly three times on what appears to be a nondescript door and calls cheerfully: "You ready to come out?"

The reply is inaudible, but beneath his mask, he appears to be grinning as he yanks the door open — and four scientists who have spent a year away from all other human contact, simulating a mission to Mars, spill out to cheers and applause.