Space walk prepares for solar panels

Leroy Chiao spent seven hours adjusting cables

Astronauts from the space shuttle Discovery have taken part in the third of four scheduled spacewalks to prepare the International Space Station for a permanent crew.

Leroy Chiao and Bill McArthur re-routed cables and installed power converters ahead of the arrival of large solar-panelled "wings".

The astronauts were out of Discovery for almost seven hours.

There will be another spacewalk on Wednesday

"It's just amazing to look at your feet and see clouds going by," said Bill McArthur some 370 kilometres (230 miles) above the Earth.

The pair were working on the Z-1, a metallic structure which houses gyroscopes and radio communications equipment.

Solar energy

It will be the base for solar panels, each more than 30 metres (100 feet) long, longer than the space station itself.

The converters will regulate the electricity generated by its photoelectric cells to a steady 125 volts for use by the station.

When eight panels are in place, the space station will be large enough to cover a football field, and one of its most important jobs will be to provide solar power energy - enough to give electricity to 55 homes.

The ability to do energy-intensive science sets it apart from stations like the US Skylab and Russia's Mir.

Hundredth mission

Discovery's 11-day mission is the 100th for the US shuttle programme and the last before the International Space Station becomes permanently occupied.

The Expedition One crew of two Russians and their American commander is set to arrive in early November after launch from a Russian-owned rocket complex in Kazakhstan.

The station is a joint effort by the United States, Russia, Japan, Europe and Canada.