Oh, wow! Beautiful view

Scott Altman Columbia commander

Astronauts John Grunsfeld and Rick Linnehan began their first spacewalk shortly after 0630 GMT to replace the telescope's solar panels with more efficient versions.

The walk is one of five the team have planned over the next week as they prepare to install a new electrical power unit and a new camera.

"Oh, wow! Beautiful view," shuttle commander Scott Altman exclaimed to ground control as he emerged from the Columbia, which at the time was soaring high above the African continent.

Hubble was captured by Columbia's 15-metre-long robotic arm on Sunday and secured to the shuttle's cargo bay.

Hitches

The success of the operation brought a collective sigh of relief at mission control back on Earth after a series of hitches nearly aborted the Columbia orbiter's 11-day mission.

Mission control gave the go-ahead for the grab on Saturday after deciding that a problem with a radiator line would not after all interfere with the shuttle's work.

It broke the good news to the crew to the music from the spy film Mission Impossible.

Currie: Long experience with robotic arm

"Your mission, if you choose to accept it, is to rendezvous and grapple the Hubble Space Telescope and then spend five days massively re-outfitting and upgrading the telescope," controllers said in the tongue-in-cheek message, adding that the tape would "self-destruct in five seconds".

It fell to Nancy Currie, a US Army helicopter pilot, to wield the robotic arm as both the shuttle and telescope moved at a speed of eight kilometres a second about 580 kilometres above the Pacific Ocean south-west of Mexico.

The astronaut previously notched up two triumphs with the robotic arm when she joined the first two modules of the International Space Station.

Blockage fears

Columbia blasted off on its 11-day mission on Friday but ground controllers soon detected a blockage in a radiator line used to cool the shuttle's electronics system.

Hubble history

1977 - Project begins 1985 - Hubble built 1990, 24 April - Hubble launched 1990, 18 May - First light 1993, December - Flawed mirror corrected 1997, February - Second servicing mission 1999, December - Emergency service to repair gyroscopes 2002, March - Repairs not done in 1999 2010 - End of Hubble mission

It is believed the blockage may be debris from a welding job carried out during the shuttle's recent overhaul. Problems may arise, however, when the shuttle re-enters the Earth's atmosphere on its return.

The 12-year-old orbiting Hubble observatory has taken some astonishing pictures of deep space and is expected to do even better after its upgrade.

"It's an incredibly beautiful object," Hubble programme manager Preston Burch told the Associated Press news agency.

The shuttle is on an 11-day mission

"We live with it 24 hours a day, seven days a week, so we're always conscious of its state of health."

The Columbia crew must fit Hubble with a new camera, solar wings, a power-control unit, a steering mechanism and a refrigerator system that should allow scientists to use an infrared camera.

The most daunting part of the mission will be spacewalk number three, during which the team will remove and replace the telescope's power unit. Astronauts will have to switch the telescope off and the American space agency (Nasa) cannot guarantee that it will be able to switch the observatory back on again.