Astronauts wrap up space walk

DALLAS, Dec 13 (Reuters) Two spacewalking astronauts added a new piece to the metal backbone of the International Space Station clearing the way for a critical power rewiring later this week.

Space shuttle Discovery crew members Robert Curbeam, who was making his fourth spacewalk, and partner Christer Fuglesang, a rookie flier and Sweden's first astronaut, finished their work at 10:07 pm 0837 IST.

The walk's duration yesterday was six hours and 36 minutes.

It was the first of three scheduled for this mission with the next set to take place tomorrow.

A NASA spokeswoman said the pair had also replaced a faulty camera during their foray, among other tasks.

Curbeam and Fuglesang guided robot arm operator Joan Higginbotham, who was nudging an 3.3-metre beam into position. The beam is a connecting piece that will act as a spacer between two power modules.

''This is going to be really slow motion,'' Higginbotham said, as she prepared to move the two-ton segment.

''Keep coming, keep coming,'' Curbeam called out.

Clearance was as tight as 5 cm as Higginbotham maneuvered the new piece into position at the end of the solar array truss, which was delivered to the station in September.

It took a couple of tweaks to properly align all four corners of the beam so it could be bolted into place.

During the maneuver, flight controllers told the crew that Discovery's heat shield had passed all inspections and no additional surveys would be needed.

''That's outstanding news,'' shuttle commander Mark Polansky said. ''We're happy to hear that we can go on with normal (station) assembly tomorrow.'' NASA has been meticulous about scouting the shuttle for damage since losing Columbia and seven astronauts in 2003 because of a debris strike.

The shuttle Discovery astronauts floated aboard the International Space Station on Monday, the start of a weeklong stay to hook up a new power system so new laboratory modules can be added to the complex.

REUTERS LL DS1100