Space Station's Dextre Robot Passes Crucial Test

This illustration depicts the Canadian Space Agency's Dextre maintenance robot at the end of the International Space Station's Canadarm2. Dextre and a Japanese module will be delivered to the ISS during NASA's March 2008 STS-123 mission. CREDIT: NASA

Canadian engineers put the International Space Station's Dextre robot through a workout last week, showing that the handyman is ready for duty when a Japanese cargo freighter arrives at the orbiting lab in January.

Dextre relocated a cargo transport container from one stowage location to another on the space station's truss backbone. The maneuver was accomplished Dec. 22 and Dec. 23.

Mounted on the end of the station's robot arm, Dextre grappled the 974-pound cargo carrier and mounted it on a caddy workbench on Dec. 22. Then the robot arm moved to the container's new location Dec. 23, and with the help of engineers on the ground, Dextre placed its cargo on a storage rack with a precise alignment within one degree of perfection.

A set of power controllers is packed inside the cargo transport container.

Outfitted with two 11-foot-long (3.3-meter-long) arms, Dextre is designed to assume routine maintenance tasks outside the space station that would normally require a spacewalk by astronauts.

Dextre's arms include tool-grasping grippers and arm joints to give the robot human-like skills for repair work outside the space station. [Diagram of Dextre robot]

"When astronauts train to do this type of task during a spacewalk, they get to practice again and again until they are comfortable with the procedure," said Tim Braithwaite, the Canadian Space Agency's representative at NASA's Johnson Space Center in Houston.

Last week's operation is billed as a final exam by Canada, which provides the bulk of the space station's robotics equipment. It also frees space for the Alpha Magnetic Spectrometer, a major international physics experiment due to arrive at the station in April.

Dextre is commanded from mission control in Houston, while engineers in St. Hubert, a suburb of Montreal, stand ready to assist.

"We're operating a new robot via remote control, doing a task that has never been done robotically, with precision levels that have to be near-perfect," Braithwaite said. "So this test is also about gaining experience for the ground team and learning how to operate Dextre's complicated systems."

Dextre will transfer two unpressurized payloads from Japan's HTV resupply freighter to the space station early next year.

After the HTV berths with the station, the outpost's robot arm will pull an exposed pallet from the spacecraft and place it on a temporary platform. Dextre will pluck a cargo container and a spare flex hose rotary coupler from the pallet and move the payloads to permanent positions on the space station.

The HTV is scheduled to launch Jan. 20 and arrive at the station one week later.

The cargo transfer duties are the first significant operational tasks for Dextre, which launched on a space shuttle flight in 2008.

• Video: Introduction to Canada's Dextre Robot
• Space Station's Dextre Robot Passes Crucial Test
• Graphic: Inside and Out: The International Space Station