Astronauts Prepare for Spacewalk to Assemble Giant Machine

With power now flowing to the international space station's new robot, the astronauts aboard the linked shuttle-station complex started preparing Saturday for a spacewalk to assemble the giant machine.

On Friday night, astronauts used the space station's mechanical arm to grab onto and energize Dextre, bypassing a faulty cable that wasn't able to transmit power to the robot.

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The robot, designed to help maintain the space station, could not be completely put together or tested without power to heat its joints and electronics.

"That was a great workaround that the ground came up with and kind of saved the day," astronaut Garrett Reisman said in a televised interview with the Web site.

The power bypass kept NASA on track for Saturday night's spacewalk to hook the robot's 11-foot arms to its torso. Spacewalkers have already attached the robot's hands to its arms.

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Phil Engelauf, chief of the flight directors' office, said everyone on the ground was relieved to see the power problem resolved.

"There was obviously some real concern over the last day or two for getting that powered up," he said.

The shuttle Endeavour and its seven-man crew delivered Dextre — lying in pieces on its transport bed — to the space station. It was attached to the exterior of the orbiting outpost on Thursday.

The problem cable is in Dextre's transport bed, or pallet, which the astronauts are using as a staging area to assemble the robot.

The pallet originally was supposed to be attached to one part of the space station and the cable was designed accordingly, said Pierre Jean, Canada's acting space station program manager. The cable should have been updated when officials changed the attachment point, but it wasn't, he said.

Supplying power directly to Dextre, via the space station's robot arm, circumvented the cable and transport bed.

Jean said the Canadian Space Agency and its main contractor were responsible for designing the cable, but he was reluctant to blame anyone for the error.

"In this case this is not something that was done by negligence or anything like that," he said late Friday.

Earlier in the day, LeRoy Cain, chairman of the mission management team, promised a full investigation "to run this to ground and understand exactly what happened and how and why."

The Canadian-built robot — which cost more than $200 million — is intended to be a helper for spacewalking astronauts. It ultimately could take over some spacewalking jobs, saving time for space station crews while reducing their risk.

Once it's completely assembled early next week, the robot will be removed from its transport bed. From that point on, it will be powered from its various attachment points directly on the space station.

Endeavour also delivered the first segment of Japan's Kibo lab, a 14-foot-long storage compartment. Japanese astronaut Takao Doi entered it for the first time late in the day.

The $1 billion lab itself will fly to the space station in May, aboard shuttle Discovery.

Five spacewalks are planned for Endeavour's nearly two-week visit, the longest ever by a shuttle.

On Friday, mission managers concluded that Endeavour's heat shield made it through Tuesday's liftoff in good shape and formally cleared the shuttle for re-entry on March 26.