Houston: Amidst a million excited spectators, the final space shuttle Atlantis soared into the heavens and soon to be in history books on Friday, kicking off the last ever mission of NASA's shuttle programme.

Atlantis blasted off at 1856 IST from launch pad 39A from the Kennedy Space Centre, signaling the start of the final chapter of the storied 30-year NASA space programme.

At least 750,000 to one million people turned out to watch history unfold before their eyes.

They descended on Florida's "space coast" over the past several days, watched Atlantis's four crew members — Chris Ferguson, pilot Doug Hurley, flight engineer Rex Walheim and Sandy Magnus — under cloudy, but rain-free skies.

Shuttle beat the weather despite a bleak forecast of thunderstorms and clouds.

The countdown toward liftoff took a dramatic pause at T minus 31 seconds while ground crews verified that the scaffolding around the shuttle was fully retracted.

NASA was quickly able to push on toward liftoff.

"Good luck to you and your crew on the final flight of this true American icon. Good luck, god speed and have a little fun up there," shuttle launch director Mike Leinbach told the crew just before launch.

"Thanks to you and your team Mike," Commander Chris Ferguson replied. "We're completing a chapter of a journey that will never end. The crew of Atlantis is ready to launch."

After 135 launches over 30 years, the space shuttle will never streak into the sky again as the programme was cancelled last year in favour of focusing on deep-space missions.

Private companies, such as SpaceX, Boeing and Sierra Nevada will likely to compete to become the first to build a next-generation space capsule that could take astronauts and their equipment to the International Space Station.

Earlier this week, US President Barack Obama praised the shuttle programme but said it was time to focus on new projects.

"Let's start stretching the boundaries so we're not doing the same things over and over again. But rather, let's start thinking about what's the next horizon, what's the next frontier out there," he said.

Over the next 12 days, Atlantis's crew will conduct research into robotic refueling techniques, and Canadian robotics will be a big player in those tests.

Atlantis and its four-astronaut crew are headed for a rendezvous with the International Space Station.

The main goal of the shuttle's 12-day flight —Atlantis' 33rd mission after nearly 26 years of flying — is to deliver a year's worth of supplies and spare parts to the orbiting lab.

But the world's attention is fixed more on what Atlantis' last mission means than on what it will accomplish in orbit. Commander Chris Ferguson is leading a skeleton crew of four on Atlantis' STS-135 flight.

He's joined by pilot Doug Hurley and mission specialists Rex Waldheim and Sandy Magnus.

Other shuttle missions over the years have typically carried six or seven space flyers, but NASA wanted to use every bit of available space to pack extra cargo on this last drop-off mission to the station.

The astronauts will deliver about 9,500 pounds (4,318 kilograms) of cargo to the station.
But the space shuttle didn't turn out to be cheap or completely safe. NASA once estimated launches could cost as little as USD 20 million; they've turned out to run nearly USD 1.6 billion each.

And two shuttle missions — Challenger's STS-51L flight in 1986 and Columbia's STS-107 mission in 2003 — ended in tragedy, killing a total of 14 astronauts.

Ultimately, historians will likely debate the shuttle program's legacy for years to come. When Atlantis touches down later this month, its flying days will be over.

But the orbiter will still have to be prepped for one final mission: educating the public about spaceflight, and perhaps inspiring youngsters to become astronauts themselves someday.

Like the two other remaining shuttles — Endeavour and Discovery — Atlantis will become a museum showpiece.

Atlantis won't have to go far; it will assume a place of pride in the Kennedy Space Center Visitor Complex here.

Discovery is headed for the Smithsonian National Air and Space Museum, while Endeavour will make the trip west to the California Science Center in Los Angeles.

Without the space shuttles, NASA will rely on Russian Soyuz vehicles to ferry astronauts to and from the space station, which is slated to operate until at least 2020.

The agency wants private American craft to take over this taxi service eventually, but that probably won't happen for at least four or five years. For its part, NASA has begun shifting its focus beyond low-Earth orbit.

Last year, President Barack Obama charged the space agency with sending astronauts to an asteroid by 2025, and then on to Mars by the mid-2030s.

As exciting as both of these exploration prospects are, they remain far off, both in space and time.

Right now, most thoughts are with Atlantis as it streaks toward the space station, its final mission closing out the life of a spacecraft that came to represent a nation in many ways.

Over the years, the space shuttle became a symbol of America, its ambitious goals and its technological know-how, experts say.