The shuttle lifted off its seaside launch pad at 2:01 pm (2.10 am Singapore time), heading toward an orbit 563 km above the planet and a Wednesday rendezvous with the Hubble telescope.

Once the telescope is anchored in the shuttle's cargo bay, spacewalking astronauts plan five consecutive days of work to install two new cameras, repair two other science instruments, replace Hubble's positioning gyroscopes and batteries and attach new thermal insulation.

'On this mission, we're going for broke,' said Hubble project scientist David Leckrone.

Nasa has dispatched space shuttle crews to repair and upgrade Hubble four times since it was put into orbit in 1990.

But Atlantis' mission is the first since the 2003 Columbia accident, which changed the way Nasa did business.

Because the Atlantis astronauts will be too far to reach the International Space Station in case their ship sustained major damage during launch, Nasa has a second shuttle at the launch site ready to mount a rescue mission if necessary.

Nasa hopes that with the upgrades Hubble, which has cost about US$10 billion (S$15 billion) so far, will last until at least 2014, at which time its replacement should be in orbit and operational.

Hubble's observations have been important in all areas of astronomical research, including the still-unexplained discovery that the universe is expanding at an increasingly faster rate and that galaxies formed quite early after the Big Bang explosion that created the universe 13.7 billion years ago. -- REUTERS