Space Shuttle Atlantis Heads Into Orbit

US space shuttle Atlantis lifted off last night from Florida on its mission to international space station Alpha, despite last-minute computer problems that almost delayed the launch.

With the launch, astronaut Jerry Ross became the first person to fly into space seven times.

The crew of seven astronauts is to deliver and install the "backbone" of the station - a $600m (£400m) girder that is the foundation for Alpha's expansion. The mission will take 11 days, and include four spacewalks, including two by Ross.

Lift-off had been delayed for four days because repairs had to be made to a fuel line on the launchpad at the Kennedy space centre. Strong wind threatened to further delay the start, but the weather cleared up.

A last-minute computer problem in the firing room almost forced another delay. Controllers, working to send the shuttle on its way within a set five-minute time window, reloaded the system software and launched Atlantis with 11 seconds to spare.

"We were getting down to the wire, I have to admit," launch director Mike Leinbach said.

"Maybe next time we can make it a little closer," mission control told commander Michael Bloomfield after the shuttle had entered orbit.

"I don't think I'll have any heartbeats left," he replied.

The shuttle should arrive at Alpha tomorrow. Atlantis astronauts will be the first visitors for the three-man station crew, which is four months into a six-month stay.

Alpha's new girder, which weighs more than 12,000kg and is 13 metres long, will form the foundation for a framework that eventually will stretch longer than a football field. This will hold electricity-generating solar wings and radiators needed for extra laboratories.

Attached to the girder are a $190m railcar and track, which will allow Alpha's robot arm to move from one end of the space station to the other.

It was the third shuttle launch since the September 11 terrorist attacks - and as with the previous two, security was tight.

Fighter jets and attack helicopters patrolled no-fly and no-sail zones. Three small planes violated the air space and were escorted down by F-15s; a ship was also chased away.

Under a new Nasa security policy, the astronauts' activities on launch day - normally broadcast live - were kept secret until they arrived at the pad.

"We are living in a different world post-September 11 and that means we ought to always be diligent about what we're doing to make this less of an attractive or considered target," said Nasa administrator Sean O'Keefe.