Space shuttle Discovery, nearing the end of its last flight, left the International Space Station this morning, accompanied by naval tradition and a congratulatory message from "Captain James T. Kirk" of Star Trek fame.
Station commander Scott Kelly, a U.S. Navy captain, tolled a ship's bell.
"Discovery departing," Kelly announced as the venerable orbiter departed.
The astronauts scheduled to return to Earth woke up to a recording from actor William Shatner, who played Kirk in the original Star Trek television series and seven movies.
"Space, the final frontier," Shatner, 79, said. "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."
Discovery has spent a full year - 365 days - in space as of the end of the current mission. The shuttle will have traveled more than 150 million miles by the time it touches down Wednesday morning at Cape Canaveral.
After leaving its dock at 8:37 AM EST today, Discovery flew in a circle around the space station. Astronauts on board the 27-year old orbiter took pictures of the ISS, while crew members aboard the space station returned the photographic favor.
Discovery delivered an equipment platform and storage compartment to the ISS. The 13-year old, multinational research facility is now about 97 percent complete.
NASA also delivered a robot called R2 to the space station.
The humanoid machine was the subject of some presidential humor during a phone call from President Barack Obama to the Discovery and ISS crews last week. Obama good-naturely urged the astronauts to unpack the three and one-half foot tall, legless automaton from its shipment container.
After retirement Discovery will be displayed at the Smithsonian Institution's National Air and Space Museum in Washington, DC.
First entering service in 1984, OV-103, as Discovery is formally known by NASA, delivered the Hubble Space Telescope to orbit and ferried astronauts to perform the second and third repair missions for that instrument.
Discovery also launched the Ulysses probe and carried Mercury astronaut John Glenn, then 77, back to space in October 1998. It also was the first shuttle to return to space after the Challenger and Columbia disasters.
Endeavor and Atlantis will join it in retirement after NASA's space shuttle program is retired upon completion of two more flights this year.