Two astronauts stepped outside the International Space Station Saturday to put together a Canadian-made robot that will take over human tasks and help reduce the need for risky spacewalks.

Mission Specialists Richard Linnehan and Mike Foreman, who arrived last week aboard shuttle Endeavour, embarked on a seven-hour spacewalk using socket wrenches and drills to bolt the Dextre robot's two 11-foot (3.3 meter) arms, NASA said.

The robot will be able to handle delicate tasks that have been performed by spacewalkers, allowing astronauts to focus on research inside the orbiting outpost that is key to international space exploration ambitions.

Astronauts installed Europe's first space laboratory in a shuttle Atlantis mission last month and Endeavour's crew added the first of three parts of Japan's Kibo research facility this week.

Astronauts continued to outfit the Japanese Logistics Module Saturday after it was inaugurated by ISS Commander Peggy Whitson and Japanese astronaut Takao Doi.

"I am very proud of this occasion," Japanese program manager Tetsur Yokoama told reporters.

Dextre, sent up on Endeavour which is docked with the space station, is the third and final component of the Canadarm Remote Manipulator System, the robotic arm that is Canada's vital contribution to the station.

The 200-million-dollar robot encountered a technical glitch before its assembly, but the problem was resolved in time for Saturday's spacewalk.

The 1.56-tonne robot will conduct operations such as replacing small components on the station's exterior — tasks which until now required a human touch.

Its presence will boost crew safety by reducing the number of hours that astronauts will have to be outside the station on spacewalks, and thus allowing them to focus on other tasks such as conducting scientific experiments in micro-gravity, according to the Canadian Space Agency.

Dextre's two hands are each about the size of a small microwave oven. They are equipped with built-in socket wrenches, retractable claws used to grip objects, and remote-control high-resolution cameras.

The robot's human-like upper torso swivels at the waist, and its arms were designed with seven joints to provide it with maximum versatility. Umbilical connectors provide power and data connectivity.

With Dextre delivered to ISS in nine separate pieces, the astronauts will use three of the Endeavour mission's five spacewalks to get it up and running.

Linnehan and fellow astronaut Garrett Reisman conducted the Endeavour mission's first spacewalk Friday to lay the groundwork for the robot's complicated assembly.

Dextre's assembly will be complete with a third spacewalk set to start Monday.

NASA plans to finish building the International Space Station by 2010, at which time it will retire its three-shuttle fleet.