VIDEO: Famous wake-up call for space shuttle Discovery crew

CAPE CANAVERAL, Fla. - Space shuttle Discovery, the world's most traveled spaceship, has left the International Space Station for the last time.

Discovery undocked Monday morning from the International Space Station, wrapping up a nine-day visit there.

This is the final flight for Discovery, due back on Earth on Wednesday. It's being retired and sent to a museum. NASA's two other shuttles will join Discovery in retirement, following their upcoming missions.

Discovery's six astronauts got a special greeting in advance of their space station departure.

Actor William Shatner, who played Capt. Kirk on the original "Star Trek" TV series, paid tribute to Discovery's voyages over the decades. He said the shuttle has boldly gone and done what no spacecraft has done before.

Click the player above to hear Shatner's tribute.