Reporting from Cape Canaveral, Fla.
Atlantis lifted off Friday morning, shooting straight into a brightening sky on a 12-day mission that marks the end of the nation's three-decade space shuttle program.
There was a brief hold in the countdown at 31 seconds because of a glitch seemingly involving a piece of retractable equipment. As millions of onlookers on the ground and via television held their breaths, officials checked and reported that the equipment had, indeed, been moved.
With the last knot in the timeline unsnarled, the countdown resumed and the engines fired, sending the craft upward and out along the eastern coast of the United States.
When it returns, Atlantis will join Discovery and Endeavour as retired vessels. NASA will shift its mission to sending astronauts to asteroids and Mars while private companies take over the more mundane aspect of moving cargo and crews from Earth to orbit.
Earlier, the last four astronauts boarded Atlantis even as possible rain could have delayed the launch. Throughout the morning, meteorologists gave only a 30% chance of the flight going off as planned at 11:26 EDT.
But optimism has always been part of NASA's DNA. "We do have a shot at this today," launch director Mike Leinbach assured his team.
Television shots showed Cmdr. Christopher Ferguson giving a thumbs up as he was strapped in. The astronauts posed for pictures before boarding.
In addition to the four crew members — including mission specialists Rex Walheim and Sandy Magnus and pilot Doug Hurley — Atlantis carried a year's worth of supplies for the International Space Station.
This is the 33rd flight for Atlantis and the 135th shuttle mission overall.
Crowds were large for the final launch, with some counts putting the number approaching 1 million people, on par with the crowds that attended the Apollo moon shots. At least 14 members of Congress were attending the launch. Among the dignitaries was Robert Crippen, the pilot of the first shuttle launch.
The threat that rain would delay the launch of Atlantis was doing little to deter the visitors, who were parking on the sides of roads and filling every hotel room for miles. A 50-mile traffic jam extending all the way to Orlando was expected.
To space enthusiasts, the outpouring was confirmation that the federal government may have miscalculated how much public attention was focused on the space shuttle program, and disappointment over the plan to suspend U.S. manned launches over the next several years.
"There is no other government activity where 1 million people come to watch," said astronaut Chris Hadfield, referring to a crowd estimate by the Space Coast Office of Tourism. "That's a benchmark measure of how people view this."
Indeed, people who have waited for decades to see a shuttle launch made long drives to fulfill their dreams. Retired Air Force Sgt. Fred Lippert, 72, who drove from Kentucky with his wife, knew he was heading into a traffic nightmare and that rain could postpone the launch, but he was not concerned.
"I always wanted to see one in person, and now I got my chance," he said.
About 300 current and former astronauts who have flown aboard the shuttle made their way to the space center, said former astronaut Michael "Rich" Clifford, deputy program manager for the shuttle at Boeing Co.
"We're going to have a party on the day of the launch," he said.
Tourism officials said they did not expect the crowds to lose interest easily. Budget hotel rooms were going for $299 in nearby Titusville, and charter boats were charging as much as $300 to take viewers out to sea for the launch, said Rob Varley, executive director of the Space Coast Office of Tourism.
Tickets to view the launch from inside the space center were being auctioned on EBay for $500 each on Wednesday and reportedly had been much higher earlier in the week. The tourism office's estimate of 1 million visitors was based on hotel and car reservations, as well as past launches.
"I have never seen anything like it," Varley said.
Crowds formed at hobby and souvenir shops, purchasing polo shirts, baby outfits, virtually anything with a shuttle stamped on it. At Space Shirts, a retailer down the road from the space center, people were packed shoulder to shoulder. Eager buyers were waiting in their cars outside for parking spots in the store's small lot.
"It's hard to be prepared for something like this," said Brenda Mulberry, owner of the shop, in between swiping credit cards. "We've been busy taking care of people all day here."
NASA deputy administrator Lori Garver said at a news conference inside the space center that the end of the shuttle program would not mean a less ambitious U.S. space program, but instead a future in which NASA would dedicate itself to the more ambitious goals while leaving routine space travel to private companies.
The practical result, however, is that NASA will rely on Russia to fly astronauts to the International Space Station.
"The fact that we have to rely on the Russians makes me ill," said Titusville Police Chief Tony Bollinger. "Our politicians have let us down."