The spacecraft took off exactly on time at 2:38 p.m. Eastern Time from Launch Pad 39B at Kennedy Space Center in Florida, in a launch viewed in unprecedented detail by a new slew of cameras installed by NASA.

Cameras tracked multiple angles of the launch, including aboard the shuttle's huge external fuel tank during its climb into space, and about 10 minutes after liftoff, shuttle pilot Mark Kelly maneuvered Discovery to aim new cameras aboard the orbiter at the fuel tank to check for further damage to its foam insulation.

Discovery's launch took place despite the disclosure that NASA engineers on Sunday night had found a five-inch crack in the insulation and a three-inch triangular piece of foam that had broken off and fallen onto the launch platform.

Engineers studied both items and determined that they posed no significant risk to either the safety of the crew or the success of the launch.

Better weather also played a factor in Tuesday's liftoff. After NASA had canceled two previous attempts because of lightning-laden clouds lurking in the vicinity of the launch site, only gentle offshore rains greeted controllers. Those showers dissipated as expected and were replaced by skies containing light cloudiness and plenty of sun at launch time.

Discovery is transporting seven astronauts - six Americans and one European - to a rendezvous with the International Space Station on Thursday. Their successful mission is considered crucial to the resumption of both station construction and the U.S. presence in space.

The flight constitutes only the second shuttle mission since Columbia disintegrated over Texas on Feb. 1, 2003. That disaster occurred because a 1.5 pound piece of foam broke off the main fuel tank. Traveling at more than 500 miles (800 kilometers) per hour, the fragment punched a large hole in the leading edge of the shuttle's left wing.

Throughout Columbia's two-week mission to the space station, neither NASA nor the crew became aware of the fatal flaw that had developed in the orbiter. The accident took the lives of all seven crew members. NASA since has immortalized them by naming seven hills in the Gusev crater area of Mars - where the Spirit rover continues to operate - and seven craters on the Moon's far side, in their honor.

Bill Gerstenmaier, NASA's associate administrator for space operations, said there were no disagreements about whether to proceed with Discovery's launch on Tuesday.

Speaking with reporters, he said the piece of foam that had broken off contained less than half of the mass deemed potentially hazardous to the orbiter. In addition, he said engineers also decided the crack in the insulation posed no danger because the remaining foam was structurally sound.

"We see no concern with proceeding in that condition," Gerstenmaier said.

Nevertheless, foam issues have dogged NASA ever since the Columbia disaster. Despite intensive efforts to stabilize the crucial insulating material, a one-pound piece broke off during Discovery's launch in July 2005.

That piece of debris missed the shuttle, but NASA Administrator Michael Griffin grounded the fleet once again until the problem could be studied even further. He withdrew the grounding order this past spring, after engineers made more improvements to the foam configuration.

Griffin's decision was met with opposition from at least two NASA officials - chief safety officer Bryan O'Connor and chief engineer Chris Scolese - who urged further delay in resuming shuttle launches. A third official, Charlie Camarda, who had been director of engineering at the Johnson Space Center in Houston, Texas, resigned last week over the foam controversy.

NASA has instituted several safety contingencies to protect the lives of the astronauts if another potentially catastrophic foam incident occurs. For example, the Discovery crew could remain aboard the space station until a shuttle rescue mission could be launched.

The expanded camera coverage constitutes an additional safety measure. Along with the cameras watching the shuttle and fuel tank during liftoff, others aboard the space station will inspect Discovery after its rendezvous.

Discovery will carry 2.5 tons of supplies to the ISS, as well as the Italian-built Leonardo science module. Two members of the crew, Mike Fossum and Piers Sellers, are scheduled to undertake at least two spacewalks. ESA astronaut Thomas Reiter will remain aboard the station and serve as the third crew member.

The remaining Discovery crew includes the commander, Steven Lindsey, and mission specialists Lisa Nowak and Stephanie Wilson.

related AFP News Wire report
The Discovery shuttle rocketed seven astronauts into orbit Tuesday on a pivotal mission for US space ambitions amid persistent concerns about safety since the 2003 Columbia tragedy.

"Discovery, straight as an arrow" on its way to the International Space Station (ISS), which it will meet Thursday, said launch commentator Bruce Buckingham.

NASA employees at the Kennedy Space Center's launch control center applauded and hugged each other as ground control announced the shuttle had reached orbit about nine minutes after blasting off from Cape Canaveral, Florida under blue skies.

NASA cleared the mission despite finding a small crack in foam insulation on the shuttle's vexatious external fuel tank on the eve of the launch. Officials said the fissure posed no threat to the shuttle.

The 115th shuttle mission finally blasted off on time at 2:38 pm (1838 GMT) in a spectacular cloud of smoke on the US Independence Day, after two weekend launch attempts were scuttled by concerns over lightning-producing clouds.

Discovery jettisoned its two rocket boosters two minutes into the flight and split from the fuel tank as it reached orbit some nine minutes after blastoff.

"I cannot think of a better place to be here on the Fourth of July and on Independence Day to begin to launch," Commander Steven Lindsey said just before the final countdown.

"We hope that very soon we give you an up close and personal look of 'the rockets red glare,'" Lindsey said, quoting the US national anthem.

The two female and five male astronauts smiled broadly before boarding the shuttle, waving small American flags as they headed to the bus that took them to the launch pad before the first ever Independence Day liftoff.

The second shuttle mission to the ISS since the Columbia disaster will show whether modifications made to the fuel tank have succeeded.

Columbia was doomed by a piece of foam insulation that came loose and pierced its heat shield during liftoff, causing the shuttle to break apart into a ball of fire as it returned to Earth on February 1, 2003. Seven astronauts died.

Foam also peeled off Discovery's tank in the first post-tragedy launch last year, but the debris missed the shuttle. Nevertheless, NASA grounded the 25-year-old fleet until now to make further modifications.

NASA placed more than 100 cameras around Discovery's launch pad for Tuesday's launch to detect any loose debris. The ISS will then take pictures of the vessel's heat shield while it performs a backflip during approach.

The astronauts, led by Lindsey, will test new procedures to boost safety as well as deliver critical equipment and supplies to the ISS, where the shuttle is scheduled to dock on Thursday.

They will also drop off European Space Agency astronaut Thomas Reiter of Germany, who will join the ISS's two other crew members for a long-term stay, and will undertake two space walks.

NASA Administrator Michael Griffin stuck with his controversial decision to launch Discovery despite concerns over potentially damaging debris peeling off the orange-hued reservoir yet again.

During a flight readiness review, NASA's chief safety officer and top engineer called for a delay to redesign foam insulation on the fuel tank. The two officials eventually backed the mission.

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