Shuttle Endeavour blasts off on final flight

The space shuttle Endeavour has rocketed into space on its final flight to the International Space Station.

The shuttle blasted off as scheduled at 8:56 a.m. ET Monday from Kennedy Space Center in Cape Canaveral, Fla., two weeks after its previous unsuccessful launch attempt.

"It was an outstanding countdown," said shuttle launch director Mike Leinbach at a post-launch news conference. "Endeavour's on orbit safely. [It's a] great day here at the Kennedy Space Center."

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The 16-day mission, known formally as STS-134, is NASA's second last shuttle flight. The shuttle Atlantis will make NASA's final shuttle flight in July and then the entire shuttle fleet will be retired, following three decades of service.

Commander Mark Kelly heads the crew set to dock at the International Space Station Wednesday at 6:15 a.m. ET. Also on board Endeavour are fellow NASA astronauts Michael Fincke, Greg Chamitoff, Andrew Feustel and European Space Agency astronaut Roberto Vittori.

Among the tens of thousands of spectators gathered at the launch site to watch the launch was Kelly's wife, Arizona congresswoman Gabrielle Giffords, who is recovering from being shot in the head in January.

Her presence at the launch "inspired us all, just as America's space program has done for the past 50 years," said NASA administrator Charles Bolden in a blog post following the launch.

About 500,000 other people were estimated to be gathered on nearby roads and towns to watch the launch — more than the number that saw Discovery's final launch in February — and millions of others were expected to watch online.

Shortly before liftoff, Kelly issued a statement of thanks.

"This mission represents the power of teamwork, commitment and exploration," he said. "It is in the DNA of our great country to reach for the stars and explore. We must not stop. To all the millions watching today including our spouses, children, family and friends, we thank you for your support."

Endeavour will deliver to the space station the Alpha Magnetic Spectrometer (AMS), a particle physics detector that scientists hope will help lead to the understanding of the origin of the universe.

The shuttle will also deliver spare parts, including some specifically for Dextre, a Canadian Space Agency robot that rides on the end of the space station's Canadarm2 robotic arm. Dextre performs maintenance and repair work outside the station, such as changing batteries and cameras.

The astronauts will undertake four spacewalks during the mission. They are expected to return to Earth at 2:32 a.m. ET on June 1, at earliest.

One challenge during the mission is the fact that a Russian Soyuz spacecraft is currently docked at the space station and will be undocking while Endeavour is also berthed, said Bill Gerstenmaier, associate administrator for Space Operations at the news conference. That will make co-ordination and logistics among the multiple crews more complicated, but everyone is prepared and there is a good plan in place, he added.

Endeavour's previous launch attempt, on April 29, was halted less than four hours before liftoff after an electrical problem was detected in the shuttle's auxiliary power unit. The problem has since been repaired.

Monday's launch saw only minor issues that did not alter the plan for the mission — a damaged tile near the shuttle side hatch was quickly repaired before takeoff and foam that fell off the external fuel tank during launch did not appear to contact the shuttle.

Following its current mission, Endeavour will be put on display at the California Science Center in Los Angeles. Its Canadarm robotic arm is expected to be returned to Canada.