The torn solar panel could have given a nasty electrical shock

The energy-collecting wing developed a rip when it was being unfurled at the port end of the platform on Tuesday.

Scott Parazynski rode on the end of an extension boom to install home-made "cufflinks" to the broken section.

The repair work will enable the wing to be fully deployed and properly locked in position.

Mr Parazynski was supported from a nearby girder by spacewalking colleague Douglas Wheelock.

Mr Parazynski had to carry out the work without touching the torn solar panel, which could have given him a powerful shock if touched. His suit and tools were insulated for protection.

Vital repair

"Beautiful," said Mr Parazynsky as he completed more than fours hours of work outside the space station, more than 200 miles (320km) above the Earth.

A controller at Houston, Texas Mission Control, told the astronauts: "Nice teamwork... excellent work guys."

The repair was of vital importance to future shuttle flights.

Unless the wing can be extended fully, it may not be able to withstand the loading put on the platform when the orbiter docks.

The panel had to be lashed together where it had come apart

Nasa officials say the 35m (115ft) wing probably snagged on a guidewire, or guidewire support, as it was being unfurled.

The next shuttle, due in December, is supposed to deliver Europe's main contribution to the ISS project - its Columbus laboratory.

Failure to sort the solar panel problem would have left Nasa no choice but to delay the December flight, keeping the already much-delayed Columbus sitting on the ground even longer.

The ISS is currently being visited by space shuttle Discovery. Astronauts from the orbiter have already attached the new Harmony module to a temporary location on the station. The unit will be moved into a permanent site once the orbiter has left.