CAPE CANAVERAL, Fla. -- Discovery, the world's most traveled spaceship, thundered into orbit for the final time Thursday, heading toward the International Space Station on a journey that marks the beginning of the end of the shuttle era.
The six astronauts on board, all experienced space fliers, were thrilled to be on their way after a delay of nearly four months for fuel-tank repairs. But it puts Discovery on the cusp of retirement when it returns in 11 days and eventually heads to a museum.
Discovery is the oldest of NASA's three surviving space shuttles and the first to be decommissioned this year. Two missions remain, first by Atlantis and then Endeavour, to end the 30-year program.
Launch director Mike Leinbach anticipated it would be "tough" to see Discovery take off for the 39th and final time, and even harder when it returns March 7.
"It's a very, very personal thing that we love to do," Leinbach explained. "It's a lot more than just our livelihood. It gets in our soul."
Emotions ran high as Discovery rocketed off its seaside pad into a clear blue sky, and arced out over the Atlantic on its farewell flight. There were a few tense minutes before liftoff when an Air Force computer problem popped up. The issue was resolved and Discovery took off about three minutes late, with just a few seconds left.
"The venerable veteran of America's human spaceflight fleet," as the launch commentator called it earlier in the day, will reach the space station Saturday, delivering a small chamber full of supplies and an experimental humanoid robot. The orbiting lab was soaring over the South Pacific when Discovery blasted off under the command of retired Air Force Col. Steven Lindsey.
NASA is under presidential direction to retire the shuttle fleet this summer, let private companies take over trips into orbit and focus on getting astronauts to asteroids and Mars.
Unlike the first try back in November, no hydrogen gas leaked during Thursday's fueling.
NASA also was confident no cracks would develop in the external fuel tank; nothing serious was spotted during the final checks at the pad. Both problems cropped up during the initial countdown in early November, and the repairs took almost four months.
Packed aboard Discovery is Robonaut 2, or R2, set to become the first humanoid robot in space.
Discovery already has 143 million miles to its credit, beginning with its first flight in 1984. By the time this mission ends, the shuttle will have tacked on another 4.5 million miles. And it will have spent 363 days in space and circled Earth 5,800 times.
No other spacecraft has been launched so many times.
Discovery's list of achievements include delivering the Hubble Space Telescope to orbit, carrying the first Russian cosmonaut to launch on a U.S. spaceship, returning Mercury astronaut John Glenn to orbit, and bringing shuttle flights back to life after the Challenger and Columbia accidents.
Discovery is expected to be put on display by the Smithsonian Institution.