CAPE CANAVERAL, Fla. - A space shuttle took flight for the next-to-last time Monday as Rep. Gabrielle Giffords, still recovering from a gunshot wound and hidden from public view, watched her astronaut husband rocket through the clouds in a deafening roar.

Giffords and the other crew families were described as awe-struck and silent on the rooftop of the launch control centre.

"Good stuff, good stuff," she said from her wheelchair when it was quiet again, according to a congressional aide.

Giffords joined the other five astronauts' wives and children on top of the Kennedy Space Center building to watch Endeavour's last voyage as NASA winds down the 30-year-old shuttle program. After liftoff, there were hugs all around, the aide said.

Endeavour disappeared so quickly into the clouds that the launch manager apologized later to the hundreds of thousands who jammed nearby roads and towns.

Giffords' husband, Mark Kelly, is Endeavour's commander and his twin astronaut brother, Scott, gave red tulips to Giffords once he safely reached orbit.

Kelly carried her wedding ring into space, which he has done in the past. This time, she wanted something back: his ring to stay on Earth. She had it around her neck on a silver chain from a funky Arizona jewelry store that included a heart and an Arizona map.

"She was very proud. She's always proud of Mark," Giffords chief of staff Pia Carusone said at a press conference.

Giffords has difficulty speaking, but Carusone said Giffords' comment after the launch was one of the congresswoman's oft-used expressions.

That Giffords would watch the shuttle launch seemed improbable a little more than four months ago. The would-be assassin shot her in the head, critically wounding her, killing six people and injuring 12 others at a political event in her hometown of Tucson, Arizona.

The bullet pierced the left side of Giffords' brain, affecting speech and movement on her right side.

Her doctors have said she has made remarkable progress in what will be a long recovery.

The tragic event made the relatively unknown congresswoman and astronaut America's sweethearts, Gabby and Mark. And it drew attention to what became known as the Mark Kelly flight once he made the decision to fly while she continued rehabilitation.

Monday's 8:56 a.m. liftoff generated the kind of excitement seldom seen on Florida's Space Coast on such a grand scale -- despite a delay of more than two weeks from the original launch date because of an electrical problem.

This time the countdown was close to perfect, and the launch made up in sound what it lacked in visuals.

"That was four seconds of cool," said Manny Kariotakis of Montreal. The day care owner said he got goosebumps watching the liftoff with thousands along U.S. 1 in Titusville, about 10 miles (16 kilometres) away.

Just before launching, Kelly thanked all those who put hands "on this incredible ship."

"It is in the DNA of our great country to reach for the stars and explore. We must not stop," he said.

Endeavour and its experienced crew of five Americans and an Italian are headed for the International Space Station. They will arrive at the orbiting outpost Wednesday, delivering a $2 billion magnetic instrument that will seek out antimatter and dark energy in the universe.

On Tuesday, they will check their ship for any launch damage to Endeavour's thermal shield. Only a couple of small bits of insulating foam came off the fuel tank during the crucial phase of liftoff, officials said.

It was a trip that Kelly almost didn't make.

The Navy captain, 47, took a leave from training to be by his wife's side after she was wounded in the Jan. 8 shooting. But Giffords improved and after two weeks in intensive care in Tucson, she was moved to Houston where Kelly lives and trains.

Her days were filled with rehab, and he yearned to see the shuttle mission through. A month after the shooting, he announced he would fly, saying he expected his wife to be well enough to be at the launch.

And she was. But electrical trouble grounded the shuttle on April 29. Hordes of visitors had gathered, including President Barack Obama and his family.

Repairs took care of the problem, and Giffords made a return visit to Florida to see Kelly off. He bid her goodbye at the exclusive beachfront house the crew uses before launch. It's the third time she's seen her husband soar into space -- in 2006, the year before they were married, and again in 2008.

"Who would have thought four and a half months ago that this would have been possible?" said Ron Barber, Giffords' district director who was shot in the face and thigh during the shooting. He went to the launch attempt two weeks ago but watched Monday from home in Tucson.

Giffords watched in private -- as do all astronauts families. She has been shielded from public view since the shooting. The only photograph provided Monday showed her red tulips with the single long-stemmed red rose for each of Kelly's two teenage daughters from a previous marriage.

"She understands, if not everything, close to everything. There's hardly a moment that we have where we feel that she's not quite grasping," Carusone told reporters.

The next medical hurdle is the replacement of part of Giffords' skull that was removed in an emergency operation after the shooting to relieve swelling, Carusone said. Giffords returned to Houston and rehab hours after the launch.

This is the 25th and final flight of Endeavour, the baby of NASA's shuttle fleet. It was built to replace Challenger, destroyed during liftoff 25 years ago this past January, and made its maiden journey six years later to capture and repair a stranded satellite. That first flight ended 19 years ago Monday.

AP writers Mike Schneider in Titusville, Florida and Jacques Billeaud in Phoenix contributed to this report.