Space shuttle Discovery lifts off Thursday from the Kennedy Space Center in 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.

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 now making one last reach for the stars,” the Mission Control commentator said once the shuttle cleared the launch tower.

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.

It was Discovery’s 39th launch and the 133rd shuttle mission overall.

There were several tense minutes just before liftoff when an Air Force computer problem popped up and threatened to halt everything. The issue was resolved and Discovery blasted off three minutes late, with just two seconds to spare.

“Great way to go out,” said launch director Mike Leinbach. Launching late in the window like that “probably makes it a little bit more sweet.”

“I would say we scripted it that way,” added Mike Moses, chairman of the mission management team, “but I could use a little less heart palpitations in the final couple seconds of the countdown.”

As the final minutes ticked away, commander Steven Lindsey thanked everyone for the work in getting Discovery ready.

“And for those watching,” he called out, “get ready to witness the majesty and the power of Discovery as she lifts off one final time.”

Emotions ran high as the shuttle rocketed off its seaside pad into a late afternoon clear blue sky, and arced out over the Atlantic on its farewell flight. Discovery will reach the space station Saturday, delivering a small chamber full of supplies and an experimental humanoid robot.

“Look forward to having company here on ISS in a couple days,” station commander Scott Kelly said in a Twitter message.

The orbiting lab was soaring over the South Pacific when Discovery took off.

On-board TV cameras showed some pieces of foam insulation breaking off the shuttle’s external fuel tank four minutes into the flight, more than usual in fact. But it shouldn’t pose any safety concerns because it was late enough after liftoff, officials said.

NASA is under presidential direction to retire the shuttle fleet this summer, let private companies take over trips to orbit and focus on getting astronauts to asteroids and Mars.

An estimated 40,000 guests gathered at Kennedy Space Center to witness history in the making, including a small delegation from Congress and Florida’s new Gov. Rick Scott.