The space shuttle Endeavour vaulted elegantly into the sky Monday, a spectacle of fire and power lent a grace note by the wounded congresswoman watching from a wheelchair below.

As Endeavour streaked into space, Rep. Gabrielle Giffords (D-Ariz.), who had watched from a rooftop with her husband’s wedding ring hanging from a silver chain around her neck, looked up and said, “Good stuff. Good stuff,” according to her chief of staff, Pia Carusone.

Giffords’s appearance here to watch her husband, Mark E. Kelly, command Endeavour’s final mission added a new chapter to a remarkable saga of survival and recovery, nearly 4½ months after she was shot in the head in an attack in Tucson that left six others dead.

The couple swapped wedding rings before the flight, a twist on their usual habit of merely sending Giffords’s ring into space with Kelly. Hers is now with Kelly in low Earth orbit, along with a photograph of the couple and a note that Giffords wrote him with her left hand. She was right-handed before the shooting, but so much has changed. One thing that remained untouched, though, is her voice, Carusone said. “It sounds as it did before the shooting,” Carusone said.

Giffords observed the earth-shuddering takeoff from the rooftop of the Ken­nedy Space Center’s launch control center, surrounded by astronaut families she’d bonded with before the shooting turned her into an internationally known figure. “There were hugs all around,” Carusone said. Scott Kelly, her husband’s twin brother and an astronaut himself who recently returned from the international space station, brought red roses for Giffords and Kelly’s children from a previous marriage, Claire and Claudia, Caru­sone said.

Giffords will return Monday to Houston, where she is rehabilitating, and is not sure whether she’ll return for the planned wee-hours landing of Endeavour on June 1, Carusone said. Each move is made in consultation with Giffords, as well as her doctors, Carusone said. “She understands, if not everything, close to everything, to the point where she understands sarcastic humor,” said Carusone, who added that there is no timetable for Giffords’s return to Congress.

“Our hope is that she can return to her life both personally and professionally,” Carusone said shortly after Endeavour took off on the penultimate flight for a 30-year-old U.S. space shuttle program soon to go the way of the dinosaurs.

Endeavour is a craft born of sorrow — it was built as a replacement for the shuttle Challenger, which exploded 73 seconds after launch in 1986, killing all seven crew members. But in its final flight, Endeavour’s bittersweet legacy was entwined with joy over Giffords’s rapid recuperation from the damage caused by the Jan. 8 shooting.

Reminders of Challenger are always there on launch day. The commander’s final communication was: “Roger, go at throttle up” — the standard script for every shuttle launch. And, sure enough, on Monday, anyone listening to the live feed of Endeavour’s liftoff heard a voice from the cockpit say, “Roger, go at throttle up.”

“Every single time you just hold your breath,” said Chris Cardinal, a space fan so dedicated that he and his fiancee, Nina Tallman, returned to Cape Canaveral on Monday after making the trip from Arizona and going away disappointed April 29. “That’s kind of the spooky time. You choke up, hold your breath and hope for the best.”

Giffords has delighted doctors with the pace of her recovery, even going out to dinner with her husband recently. She was flown to Florida by NASA, and her staff reported on her Facebook page that it was a “smooth flight with STS 134 astronaut Greg Johnson’s family.”

In the days before the launch, she spent time at NASA’s Beach House, a traditional refuge for astronauts and their families. “Who’s ready for the greatest show on Earth?” her Twitter feed read on the morning of the launch. During the weekend, her Facebook posting said: “Thanks to NASA for great fly by of launch pad.” Staffers said they write the messages for her.

Moments before the launch, Kelly could be heard from the cockpit, saying: “It is in the DNA of our great country to reach for the stars and explore. We must not stop.”

Endeavour, which was originally scheduled to launch in November, blasted off more than two weeks after its highly anticipated April 29 launch was scrubbed because of problems with the ship’s hydraulic system.

The scrub — just moments before astronauts were to board the shuttle — came as Giffords looked on. President Obama, with his wife and daughters, had also flown in for the launch. This time, the president is headed to Tennessee to survey flood damage and speak at a high school graduation.

On Monday morning, Kelly and the other five members of the crew, clad in orange flight suits, boarded the “Astrovan” bound for Launch Pad 39A. Endeavour, riding piggyback on a huge orange fuel tank, waited for them, glowing brilliantly under powerful spotlights.

“Breakfast consisted of 2 eggs, 2 slices of bacon, fruit cup and an English muffin. Coffee was bold blend from Rwanda — black,” Johnson tweeted. “Slept great.”

In Arizona, those injured along with Giffords in the shooting have closely tracked plans for the shuttle launch, hoping for the best. In a recent phone interview, Mavy Stoddard, who lost her husband in the attack and was shot and injured herself, called the congresswoman “a survivor and a fighter.”

As the clocked ticked down to the 8:56 launch time, the echoes of the aborted April 29 launch still reverberated with the hundreds of thousands of people — many of them self-described “space nerds” — who flooded into the area to watch history unfold.

NASA technicians determined the most likely failure was inside a switch box in the shuttle’s aft compartment and electrical wiring connecting the switch box to heaters used to keep the hydraulic system from freezing.

Early Monday, word that crews had discovered a small area of damaged tiles near the crew hatch set to chattering a group of fans gathered for a NASA Tweetup.

“Anybody got glue?” Tom LaRoch, a database administrator from East Longmeadow, Mass., called out to the crowd gathered on a small grandstand.

“Speed tape would be better!” Jonathan Reichhold, a software engineer from San Francisco, opined.

“It’s crowd-sourced shuttle repair!” said Lauren Sell of Philadelphia.

The enthusiasm of the crowds stood as a testament to the enduring appeal of a space program fraught with mixed emotions. The final shuttle flight is expected in June or July, raising fears that the iconic space agency will abandon manned spaceflights.

At the same launch facility where Endeavour arced into the sky, there sits unused a $500 million mobile launcher, created for a rocket — the Ares 1 — that has not been built and may be scuttled by recent federal government policy changes. In the towns by the Kennedy Space Center, the talk is more of layoffs than of grand ambitions.

Still, Endeavour’s final mission represented a kind of possible soaring coda for the shuttle program. The shuttle — a craft sometimes derided as an expensive “space truck” — carried into space a $2 billion particle physics detector imbued with great hope by scientists who believe it could help unravel the mysteries of elusive dark matter and strange matter.

The device, known as the Alpha Magnetic Spectrometer-2, was coddled in the days before the launch by technicians wearing hairnets, evoking surgeons in an operating room. It employs a powerful magnet to search for cosmic rays and was conceived by Nobel Prize-winning physicist Samuel C.C. Ting. Critics, however, have questioned the huge cost of the device.

“This kind of science is not worth billions of dollars,” Gregory Tarle, an experimental physicist at the University of Michigan, said recently. In some physicist circles, Tarle said, “people are shaking their heads that Sam could do this.”

Endeavour will also carry Legos into space for future use in educational programs, as well as worms that descended from the worms found in the wreckage of the ill-fated Columbia space shuttle.

Kelly, the ship’s commander, is making his fourth flight, having already logged 38 days in space. Endeavour, which first flew in 1992, will live on as a museum exhibit in retirement at the California Science Center in Los Angeles. But before then, it will have to return to Earth safely, following a planned 16-day mission to the international space station that is scheduled to include four spacewalks.

“We want picture-perfect,” Mary Reed, who was shot in the back and both arms in the Tucson attack, said in a phone interview. “We’ve had enough excitement for this year.”

Staff writer Brian Vastag contributed to this report.