Astronauts do some orbital plumbing

Plumbing work 390 km above the Earth

Astronauts Michael Lopez-Alegria and John Herrington completed their second stint outside the International Space Station (ISS) on Thursday, continuing construction work on the orbiting outpost.

The two men, who went up to the platform in the Endeavour shuttle, were "walking" in the vacuum of space for just over six hours.

Their tasks involved plumbing work on the platform's newest addition, a 13.5-metre-long (45 feet) hi-tech beam.

The Port One (P1) truss, as it is known, contains piping that is part of a cooling system for the ISS.

The most dramatic moment in the spacewalk came when Herrington was carried high above the space station on a robotic arm so he could guide a 270-kilogram (600 pounds) rail cart from one side of the platform to the other.

Crew briefing

The ISS now has two carts on a track so astronauts can move equipment around the exterior of the station more easily.

The track stretches more than 40 m (130 ft) over three linked beams. By the time eight more girders and sets of track are connected over the coming year, the framework will extend more than 100 m (330 ft) and support giant solar wings.

The third and last spacewalk of the current shuttle mission to the ISS is scheduled for Saturday.

Inside the station, the Expedition Five crew - Valery Korzun, Peggy Whitson and Sergei Treschev - continued its handover to the relief crew, Expedition Six.

Ken Bowersox, Nikolai Budarin and Don Pettit will live in space until March next year. Expedition Five will go home with Endeavour when it departs on Monday