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(CNN) -- The Space Shuttle Discovery launched late Thursday afternoon from Kennedy Space Center in Florida, marking the start of its 39th and final flight.

"This was a pretty successful day," said Bill Gerstenmaier, NASA's associate administrator for space operations. "It was just an amazing event."

The six-member crew will deliver a storage module, a science rig and spare parts to the international space station during its 11-day mission.

Originally scheduled for November, Discovery's launch had been delayed in order to make repairs to the external tank's support beams.

And NASA halted its countdown on Thursday, at five minutes, because of a computer problem related to safety on the "eastern range." But after a confirmation that all was good to go, the countdown resumed, and the shuttle lifted off about three minutes behind its planned 4:50 p.m. ET launch.

Five minutes in, NASA's official blog reported "a good separation for solid rocket boosters," which separated from the main shuttle after pushing the shuttle through Earth's lower atmosphere. Shortly thereafter, the blog reported that the Discovery and its astronauts were "safely in orbit," having "performed flawlessly" on its launch.

Gerstenmaier noted, and video showed, four pieces of foam tearing apart from the shuttle about four minutes into launch. But the NASA administrator called these incidents "typical" and likely harmless, since they came off "after the area of concern" when the atmosphere was so thin to make its impact negligible.

The crew is headed by Steve Lindsey, and includes a late addition in Steve Bowen -- who became the first ever astronaut to fly consecutive missions after he was assigned to take the place of Tim Kopra, when Kopra was injured last month in a bicycle accident, according to NASA.

Prior to Thursday's launch, Discovery had spent 352 days in orbit, circling the Earth 5,628 times. It has also carried 246 crew members, more than any space vehicle in history.

"In a way, it's ... sad to see the last flight," said astronaut Steven Swanson. "It's such a wonderful vehicle."

The last scheduled launch of Space Shuttle Endeavour is set for April 19 and will be commanded by Mark Kelly, the husband of U.S. Rep. Gabrielle Giffords, who is recovering from being shot last month in Tucson, Arizona. Atlantis is tentatively scheduled to launch during the summer.

The 30-year shuttle program should have ended a long time ago, NASA's administrator told CNN on Wednesday.

"What is not acceptable is the fact that the most powerful nation in the world, the United States of America, finds itself in a situation that we didn't do the proper planning to have a vehicle in place to replace shuttle when it lands its last landing," Charles Bolden said.

Bolden hopes that at least two commercial space companies will emerge to transport astronauts to the International Space Station. This will allow NASA to concentrate on building a new heavy-lift rocket capable of leaving lower Earth orbit.