Discovery, the world's most traveled spaceship, left the International Space Station on Monday for the last time, getting a send-off by the dozen orbiting astronauts as well as "Star Trek's" original Capt. Kirk.
The shuttle undocked from the station as the two craft sailed more than 320 kilometres above the Pacific, just north of New Guinea.
Station skipper Scott Kelly rang his ship's bell in true naval tradition, as the shuttle backed away. "Discovery departing," he called out.
This is the final flight for Discovery, which is due back on Earth on Wednesday. It's being retired and sent to the Smithsonian Institution for display. 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. James Kirk on the original "Star Trek" TV series, paid tribute to Discovery's voyages over the decades.
Space, the final frontier," Shatner said in a prerecorded message. "These have been the voyages of the space shuttle Discovery. Her 30-year mission: to seek out new science, to build new outposts, to bring nations together on the final frontier, to boldly go and do what no spacecraft has done before."
Shatner's words were followed by Monday morning's wake-up music, "Theme from Star Trek." It was the runner-up in a pick-the-wake-up-music contest sponsored by NASA. The No. 1 vote-getter will be beamed up Tuesday.
Discovery will have racked up nearly 150 million miles by trip's end, accumulated over 39 missions and nearly 27 years, and spent 365 days total in space. It flew to the space station 13 times.
Immediately after undocking, Discovery performed a victory lap around the orbiting outpost, where it spent the past nine days. The two crews beamed down breathtaking pictures of each other's vessel, with the blue cloud-specked planet as the backdrop. Close-up shots showed many of the individual compartments of the bigger-than-ever station.
"It looks beautiful," Kelly said of the shuttle.
Robonaut 2 yet to be unpacked
Discovery and its crew delivered a new storage compartment, as well as an equipment platform and the first humanoid robot in space. Both of the large items were successfully installed, and the shuttle astronauts even did some extra chores during their two extra days at the station. It ended up being a 13-day mission for Discovery.
R2 the robot, short for Robonaut 2, has yet to be unpacked. The space station residents hope to get to it in the next week or two.
The addition of the 21-foot-long, 15-foot wide storage compartment left the space station 97 per cent complete. The complex now has a mass of nearly 1 million pounds.
On the next shuttle flight, by Endeavour next month, a huge science experiment will be installed on the outside of the space station, wrapping up the U.S. contributions. Atlantis will blast off with supplies on the final shuttle mission at the end of June.
NASA is under presidential direction to focus more on outer space, beginning with expeditions to asteroids and then Mars.
American astronauts, meanwhile, will continue hitching rides to the space station on Russian Soyuz spacecraft, at great expense. The intent is for private U.S. companies to take over those ferry operations within a few years.
Mission Control, meanwhile, monitored a piece of space junk — an old rocket part — that possibly was going to stray too close to the space station on Wednesday. Experts wanted to wait until after the shuttle's undocking, before deciding whether the complex needed to move out of harm's way. But it was looking less likely that it would pose a concern, officials said Monday.