Safer solution: Dextre will boost crew safety by reducing the number of hours that astronauts have to be outside the station, and allow them to focus on other tasks such as conducting scientific experiments in micro-gravity.
Credit: NASA
WASHINGTON DC: NASA astronauts are making a third spacewalk to finish assembling a mechanical maintenance robot named Dextre outside the International Space Station (ISS).
Two U.S. astronauts had in an earlier spacewalk attached mechanical arms to the Canadian-made robot, enabling it to take over some human tasks and reducing the need for future risky trips outside the station. Mission specialists Richard Linnehan and Mike Foreman finished their task at about 06:00pm Sydney time (07:00am GMT) Sunday, stowing away instruments and making their way into the station's airlock.
Their job got slightly complicated early in the seven-hour spacewalk when they encountered trouble unscrewing a couple of fasteners and removing one of Dextre's arms from its storage container.
Crowbar solution
The problem was eventually resolved with the help of a simple crowbar. Linnehan and Foreman, who arrived last week aboard the space shuttle Endeavour, recouped most of the lost time, performing their task using socket wrenches and drills to bolt the Dextre robot's two 3.3-metre arms.
The US$200 million robot, which was powered-up immediately after the walk, will be able to handle maintenance tasks that have been performed by spacewalkers, allowing astronauts to focus on research inside the orbiting outpost.
"Dextre looks quite a bit different today," observed NASA flight director Dana Weigel on Sunday. "It's almost fully assembled: It has two hands, two arms and the main body is pivoted up."
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.
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 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.
Human-like torso
Its presence will boost crew safety by reducing the number of hours that astronauts will have to be outside the station, and allow 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 current 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.
NASA plans to finish building the ISS by 2010, at which time it will retire its three-shuttle fleet.
