The space shuttle Discovery and her crew of seven astronauts blasted into orbit today on America’s first manned space shot since the 2003 Columbia disaster.

The apparently successful lift off ends a two and a half year moratorium on manned space flights, devoted to making the shuttle less risky and Nasa more safety-conscious.

"Our long wait may be over. So on behalf of the many millions of people who believe so deeply in what we do, good luck, Godspeed - and have a little fun up there," launch director Mike Leinbach told the astronauts just before lift-off.

Space programme employees and relatives of both the Discovery and Columbia crews watched nervously as the shuttle rose from its pad at 10:39 a.m. (1439 GMT), climbed into a hazy midsummer sky, skirted two decks of clouds and headed out over the ocean in the most scrutinized launch in Nasa history. Two chase planes and more than 100 cameras documented the ascent from every possible angle to capture any sign of flying debris of the sort that doomed the last flight.

Video showed what might have been at least two light-colored objects flying off Discovery as the shuttle cleared the launch pad, and what appeared to be a large piece of debris coming off the external fuel tank two minutes into the flight.

Deputy shuttle programme manager Wayne Hale raised the possibility that the light-colored objects were harmless pieces of paper that protect Discovery’s thrusters before launch. But he insisted it was too soon to say what the cameras may have picked up, and he gave assurances the multitude of images will be examined frame by frame in the coming hours and days.

"No telling what might be there or what’s not there - we hope nothing," he said.

The fuel gauge that thwarted a launch attempt two weeks ago worked properly before and during the lift-off, to Nasa’s relief, and the countdown was remarkably smooth. If the sensors had acted up before lift-off, the space agency had been prepared to bend its safety rules to get the shuttle flying.

A TV camera mounted on Discovery’s giant orange external fuel tank provided an unprecedented view of the shuttle’s entire climb to orbit in spectacular orange and blue, and showed the shuttle banking away and the empty tank being jettisoned back toward Earth to burn up in the atmosphere.

"I ask you all to take note of what you saw here today: the power and the majesty of launch, of course, but also the confidence and the professionalism, the sheer gall, the pluckiness, the grittiness of this team that pulled this programme out of the depths of despair 2 1/2 years ago and made it fly," Nasa Administrator Michael Griffin said shortly after the launch.

Across the country, Americans watched the lift-off, cheering and applauding as it roared into a brilliant blue sky. "I am very proud," said Airman First Class Daniel Tureac of Brooklyn, who watched the launch on a giant screen at Times Square. "I am part of the Air Force and this is the highest up you can go, being on a shuttle crew. This is very exciting."

In the hometown of Japanese astronaut Soichi Noguchi, firecrackers were popped and congratulatory cheers of "Banzai!" rang out.

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