With a power supply problem solved, two astronauts have headed out on an overnight spacewalk to assemble the Canadian-built Dextre robot.

Mission Specialists Rick Linnehan and Mike Foreman headed out Saturday evening -- about 30 minutes ahead of schedule -- for an overnight spacewalk. Their job is to attach the huge robot's multi-joined arms to its torso.

The hands were attached on the first space walk on Friday, when the astronauts finally got power hooked up to Dextre via the space station's CanadaArm II.

A third spacewalk, scheduled for Monday night, will provide Dextre with a tool holster.

Daniel Lefebvre, a Dextre systems engineer, spoke to CTV Newsnet Saturday from St-Hubert, Que. He said there was a small sigh of relief and some clapping from the Dextre team when the robot received power after two days of problems.

He said that there were a number of redundancies built into Dextre in case of a power failure, which allowed secondary power sources to be used.

"It's not the best (situation) in the world, but we have ways of getting around things," Lefebvre said.

Dextre, a $200-million piece of equipment, was flown up to the space station in pieces contained in a transport bed aboard the shuttle Endeavour.

The bed was to be attached to a particular part of the space station, but then the attachment point was changed. The cable, meant to provide power until Dextre was fully assembled, wasn't updated.

Going without heat for more than a few days could have damaged Dextre. It needs power to heat its joints, limbs and electronics in the alternating brutal cold and searing heat of space.

Pierre Jean, Canada's acting space station program manager, said the Canadian Space Agency and its main contractor had responsibility for designing the cable.

He didn't want to attach blame. "In this case this is not something that was done by negligence or anything like that," he said late Friday.

However, LeRoy Cain, chairman of the mission management team, promised a full investigation.

Dextre should be fully assembled by early next week and will then receive its power from various attachment points on the space station.

Endeavour has also delivered the storage part of Japan's Kibo lab. The US$1 billion lab will be taken up to the station by shuttle Discovery in May.

Mission managers decided Friday that Endeavour's heat shield wasn't damaged during liftoff on Tuesday. The shuttle has been cleared for re-entry on March 26.

With files from The Associated Press