Associated Press
The space shuttle, space station and Earth are reflected in astronaut Garrett Reisman's helmet visor.

CAPE CANAVERAL, Fla. — With Dextre the robot's power problem solved, astronauts ventured outside the international space station on Saturday to put together the bulk of the gigantic walking and working machine.

The robot's hands were attached to its 11-foot arms during the first spacewalk of Endeavour's space station trip. This time, astronauts aimed to connect the arms to the shoulders. First, though, the robot was going to sit up on its transport bed, rising like Frankenstein as one astronaut put it.

Spacewalkers Richard Linnehan and Michael Foreman were so eager to get started on the robot assembly that they went out the hatch early, and quickly got the arms ready for attachment.

The nighttime spacewalk — expected to last into the wee hours today — came close to being drastically altered or even delayed. For nearly two days, a cable design flaw prevented NASA from getting power to Dextre, lying in pieces on its transport bed.

It wasn't until the astronauts gripped Dextre with the space station's mechanical arm Friday night that the robot got the power it needed to wake up and keep its joints and electronics from freezing.

"Dextre is doing much better," said astronaut Garrett Reisman, who performed the first spacewalk with Linnehan on Thursday night.

"When he's all put together, he looks a lot like a person," he added. "He's got two arms, a body, a head, and he is designed to do basically the same things that we do on a spacewalk."

At the same time, Reisman considers Dextre a little scary and monstrous-looking. Before the flight, he likened it to Frankenstein coming alive.

Once fully assembled, Dextre will stand 12 feet and have a mass of 3,400 pounds. Its shoulder span is nearly 8 feet.

A third spacewalk, on Monday night, will provide Dextre with a tool holster. That ought to do it.

The Canadian-built Dextre — which cost more than $200 million and was flown up on Endeavour — is designed to assist spacewalking astronauts. Its name, in fact, is short for dexterous. The hope is that the robot eventually will take over some of the more punishing chores, like lugging around big replacement parts.

To guard against a robotic mutiny, Mission Control jokingly told the astronauts in their wakeup mail Saturday that some new flight rules were being instituted.

No. 1, "Dextre may not injure a human being or, through inaction, allow a human being to come to harm," Mission Control wrote, quoting from science fiction writer Isaac Asimov. No. 2, "Dextre must obey orders given to it by human beings, except where such orders would conflict with the First Law."

As for Dextre's belated wakeup, Canadian Space Agency officials were reluctant to cast blame. The agency and its main contractor were responsible for designing the cable that failed to relay power to the robot, via its transport bed.

Three more spacewalks are planned during Endeavour's nearly two-week visit to the space station for a total of five. That will be the most spacewalks ever performed during a joint shuttle-station flight.