By Ed Stoddard and Irene Klotz

HOUSTON, March 15 (Reuters) - Spacewalking astronauts will work on assembling a Canadian robotic system on Saturday following the successful installation of the first segment of Japan's lab on the International Space Station.

Saturday's spacewalk will be the second of five planned during space shuttle Endeavour's busy 16-day mission in space. The plans had been in doubt until late on Friday when power was restored to the robotic system.

But Friday was Japan's moment of space glory.

Wearing protective masks and goggles, station commander Peggy Whitson, Japanese astronaut Takao Doi and lead shuttle spacewalker Rick Linnehan floated into an equipment-jammed storage closet that will be hooked up in May with Japan's main laboratory, named Kibo, or "Hope."

"This is a small step for one Japanese astronaut, but a giant entrance for Japan to a greater and newer space program. Congratulations," Doi radioed to Japan's new space control center outside Tokyo.

The cylinder is basically a storage compartment for the main segment of the three-piece Kibo, scheduled for delivery on a May space shuttle flight. The final piece will be flown up in early 2009.

It follows the installation in February of Europe's lab on the ISS, which is now truly a global affair. The opening of Kibo marks the first time in the 10 years of space station construction that equipment from all 15 partner countries is operating together in orbit.

"You are our 'kibo' -- our hope," said Japan's Mission Control commentator. Upon completion, Kibo will be about the size of a double-decker bus and the station's largest lab.

'IT'S ALIVE'

Shortly after the opening of Kibo, NASA managed to restore power to the Canadian robotic system that had been delivered to the station by the shuttle along with the first segment of Japan's lab.

"It's alive," quipped Pierre Jean, acting program manager of the Canadian space station program.

A flaw in an electrical circuit had left the $209 million robot, dubbed Dextre, without heaters to protect its systems from the minus 200-degree F (-128.88C) temperatures of space.

"It was quite a relief and a real sense of success to see it power up," Phil Engelauf of NASA's mission management team told a media briefing.

The robot, which has human-like features with a body and a pair of gangly arms, is designed to add manual dexterity and a further 30 feet (9 metres) of reach to the space station's crane to assist with detailed exterior maintenance tasks.

Engineers attempted to fix the problem with a software patch, but later discovered a hardware error was to blame.

The 1.5 tonne Dextre, brought up in nine pieces, was to be assembled during spacewalks on Saturday and Monday. Jean said the body of the robot would be raised during Saturday's spacewalk so the arms could be attached.

The spacewalk is scheduled to begin at 8:23 p.m. EDT (0023 GMT on Sunday) and will be conducted by Linnehan and Mike Foreman. It is expected to last seven hours.

The Endeavour crew reached the station on Wednesday for a 12-day construction and servicing call to the station.

The shuttle blasted off from the Kennedy Space Center in Florida on Tuesday and is scheduled to land back on Earth on March 26. (Editing by Peter Cooney)

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