'Hubble-hugger' astronauts help scientists reach further into the cosmos

Two astronauts began the first of five spacewalks yesterday aimed at giving the Hubble space telescope fresh life with a new pair of solar panels.

The US National Aeronautics and Space Administration (Nasa) said the astronauts had attached the first of the two arrays, which had successfully passed an "aliveness test".

Television pictures beamed to mission control showed the new solar panel accurately tracking the Sun – vital if the space telescope is to function – while the telescope orbited the Earth at an altitude of 350 miles. John Grunsfeld and Rick Linnehan, the astronauts, put on bulky spacesuits and left the airlock of the shuttle Columbia during a pass over the Sahara Desert on the seven-hour spacewalk.

"Hello, Mr. Hubble, the telescope. We're here to give you more power to see the planets, stars and the universe," Mr Grunsfeld said as he emerged from Columbia.

Mr Grunsfeld, an astronomer and self-described "Hubble-hugger", was making his second service call on the space telescope. He made two spacewalks on a 1999 Hubble mission. Mission Control woke the astronauts hours earlier by playing Mozart's "Variations on Twinkle, Twinkle Little Star" in a rare moment of whimsy.

The new solar panels are smaller than the ones they are replacing, which are to be returned to Earth for analysis. Each is just 25ft (8m) long, but they will deliver 20 per cent to 30 per cent more power, making it possible for Hubble to use all its scientific instruments at once. Scientists are particularly excited because the upgrades on this mission should make the telescope 10 times as powerful. But that extra power does not come without risk.

Tomorrow, Nasa will have to turn off Hubble's power for the first time in orbit, something never anticipated. There is no guarantee the power will come back on, though Nasa is confident it will. Columbia launched from the Kennedy Space Centre on Friday and is due to land there on 12 March.

Hubble is 12 years into a 20-year mission and has established itself among history's finest scientific instruments, having proved the existence of super-massive black holes, witnessed the formative stages of solar systems and charted the age of the universe.

Nasa had been unsure whether Hubble's electricity-generating solar panels would retract properly, given eight years of harsh space exposure. The replacement ones are rigid, and fold, offering more stability than the old flexible, roll-up panels. They also have more efficient gallium arsenide solar cells.