Washington - The space shuttle Atlantis blasted off from the Kennedy Space Centre in Cape Canaveral, Florida on Monday on a mission to repair the ageing Hubble Space Telescope.
The fifth and last mission to repair Hubble launched at 2:01 pm (1801 GMT). The shuttle is slated to rendezvous with the telescope on Wednesday.
The seven-member Atlantis crew will undertake five spacewalks in five straight days, adding two new instruments, repairing two others and replacing other hardware in frequently delicate operations.
Scientists say the upgrades, which US space agency NASA hopes will extend Hubble's life span until at least 2014, will continue to provide clues about the origin and nature of the universe.
Since its launch in 1990, Hubble has helped scientists to place the age of the universe at 13.7 billion years, learn that black holes are at the centre of most galaxies, monitor planetary formation and discover that the universe is expanding at an ever-faster pace.
Hubble is likely the most recognized scientific programme and has left its mark not just on astronomy textbooks, but also on the public imagination, Ed Weiler, NASA's associate administrator for science, told reporters after the launch.
'Astronomy touches people, it's a science you can see, you can feel,' he said. 'We're showing them pictures of their backyard - admittedly it's a pretty big backyard.'
With the addition of new instruments and repairs of others, scientists still hope to learn about the gases between galaxies and take detailed pictures of distant stars.
There were two minor problems with the shuttle during take-off, when there was a malfunction with a circuit breaker and an engine alarm going off for no reason, but NASA officials said neither affected the launch and would not cause issues in the future.
Just in case there is a major problem with Atlantis, another shuttle, Endeavour, has been moved to the launch pad and will be on standby if the astronauts need to find another ride home. The added precautions come after damage caused the space shuttle Columbia to disintegrate when reentering the Earth's atmosphere in 2003.
The risky mission to repair Hubble has been plagued by delays. NASA at one point was forced to indefinitely postpone the mission because of problems with the orbiting telescope's mechanisms. A launch slated for October 14, 2008, was cancelled.
NASA reluctantly scheduled the service mission under pressure from space enthusiasts who were alarmed at the prospect that Hubble would die, leaving astronomers without a replacement until the planned 2014 launch of a successor, the James Webb Space Telescope.
New instruments to be added are a new wide field camera, to replace an older model, allowing Hubble to take images in all three regions of the light spectrum, ultra-violet, visible and near infrared, and a cosmic origins spectrograph to monitor changes in light as it passes through the universe.
Additionally, spacewalkers will replace the gyroscopes that help keep the telescope pointed at a distant object, repair another camera, replace the telescope's batteries, repair a data-processing computer and install a device that will allow the telescope to be easily captured when it is time for its retirement.
The repairs will be tricky, Weiler said.
'Taking apart and putting in new pieces when wearing gloves is something we've not done before. It's a little dicey,' he said.
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