CAPE CANAVERAL, Fla. – In a majestic Independence Day liftoff, Discovery and its crew of seven blasted into orbit yesterday on the first space shuttle launch in a year, flying over objections from those within NASA who argued for more fuel-tank repairs.

NASA’s first-ever Fourth of July manned launch came after two weather delays and last-minute foam trouble that added to worries that have dogged the space agency since Columbia was doomed by a flyaway chunk of fuel tank insulation foam 3 1/2 years ago.

As Discovery thundered away from its seaside pad at 2:38 p.m., live video of the launch did not immediately reveal any sizable foam or debris flying off.

But the pictures showed smaller pieces falling from the tank, at least one hitting the shuttle.

About 4 1/2 minutes after liftoff, a bright speck could be seen flying off the fuel tank and striking Discovery’s belly. Right after launch, at least three small pieces fell.

NASA experts were reviewing images from many cameras, and engineers will spend the next few days poring over the video before the shuttle returns to Earth.

“Discovery’s ready, the weather’s beautiful, America is ready to return the space shuttle to flight. So good luck and Godspeed, Discovery,” launch director Mike Leinbach said just before liftoff.

Commander Steven Lindsey, an Air Force fighter pilot, was at Discovery’s controls and aiming for a Thursday linkup with the international space station.

“I can’t think of a better place to be here on the Fourth of July,” radioed Lindsey. “For all the folks on the Florida east coast, we hope to very soon get you an up-close and personal look at the rocket’s red glare.”

It was unclear for a while Monday whether Discovery would fly at all.

A slice of foam, no bigger than a crust of bread, fell off an expansion joint on Discovery’s external fuel tank following Sunday’s delay. Shuttle managers concluded Monday night after intensive engineering analysis that the remaining foam on that part of the tank was solid.

Engineers said the piece _ 3 inches long and just one-tenth of an ounce _ was too small to pose a threat even if it had come off during launch and smacked the shuttle. Inspectors devised a long pole with a camera to inspect the joint and found no evidence of further damage. NASA also made sure there was no excessive ice buildup at that spot yesterday.

The fallen foam, albeit harmless, added to the tension already surrounding this mission.

NASA’s chief engineer and top-ranking safety official objected two weeks ago to launching Discovery on the 12-day station delivery mission, without first eliminating the lingering dangers from foam loss, considered probable and potentially catastrophic.

They were overruled by shuttle managers and, ultimately, by NASA administrator Michael Griffin. He stressed the need to get on with building the half-done, long-overdue space station before the shuttles are retired in 2010 to make way for a moonship, per President Bush’s orders.

Griffin said he welcomed the debate over Discovery’s launch and acknowledged that the space agency plays the odds with every shuttle liftoff.