The crew's whereabouts were kept secret

It had been scheduled for Thursday, but was postponed due to a leak in fuel lines that sent clouds of hydrogen billowing into the air.

Astronaut Jerry Ross is making a record-breaking seventh flight on the shuttle.

American space agency (Nasa) technicians also had to fix a last-minute technical problem before launching the shuttle with just 11 seconds to spare in its five-minute launch window.

No-fly zone

"You spent a few extra days in Florida, but it's time for you guys to take a ride, so we wish you luck," Launch Director Mike Leinbach told the astronauts shortly before lift-off.

"We'll see you back here in about 11 days," replied shuttle commander Michael Bloomfield.

Security has been extremely tight at all launches since the 11 September terror attacks, with fighter jets and attack helicopters patrolling a no-fly zone around the launch site.

Helicopters patrolled the no-fly zone

In the morning, a plane sparked security fears when it flew close to the launch pad.

An army spokesman at the Kennedy Space Center said the pilot of a small plane had been escorted out of the launch area after entering the restricted zone.

And a ship had to be chased away from a no-sail zone surrounding the blast-of site.

ISS construction

As part of a new safety policy, the US space agency kept the new launch time secret until Sunday.

The whereabouts of the seven astronauts was also kept secret until they arrived at the pad. Only then was a video of the crew's breakfast, suit-up and departure for the pad - normally seen live - broadcast by the space agency.

Jerry Ross is the first person to do seven launches

The International Space Station and its three-man crew were flying over the Atlantic, east of Newfoundland, when Atlantis took off.

The shuttle is due to arrive at the space station on Wednesday and, a day later, the crew will fit a 12-tonne girder called Truss S0, which will form the first section of the backbone of the platform.

They are also carrying a cart that will run along rails on the backbone and allow the ISS's robotic arm to move across the station.

Grandfathers in space

Atlantis astronaut Jerry Ross is the first person to blast off from Earth seven times. He is also Nasa's most experienced spacewalker ever, having performed seven in his 22 years as an astronaut.

This weekend, when he and astronaut Lee Morin, a 49-year-old Navy doctor, venture outside of the shuttle, they will become the first pair of grandfathers to do a spacewalk.

The duo are nicknamed the Silver Team. The shuttle will also carry several scientific experiments, including one to grow wheat and mustard family plants in space.

This is part of a long-term programme to develop potential life support technologies for long space missions.