Robot mechanic goes to space

A mechanical workman will appear at the International Space Station in February to take over some of the spacewalking duties now performed by astronauts.

Dextre, a Canadian-built robot, swings two 11-foot arms and weighs nearly 3,500 pounds. When he comes to life, drawing 1,400 watts of electricity, he could relieve humans at the space station of many of the average 18 spacewalks they do for routine maintenance.

"It'll be a historic moment in robotics," Dan Rey, Dextre integration manager with the Canadian Space Agency, said. "Three generations from now, humans will be on the moon and robots will have helped get them there."

Dextre is the third and final component of the Canadian Mobile Servicing System, which includes Canadarms 1 and 2. It holds lights, video equipment, a stowage platform and three robotic tools.

While one arm will grasp the station for support, Dextre can pivot at the waist and guide payloads with the seven joints on each arm. A typical task would be to replace a 200-pound battery and engage the connectors. Spacewalks take two weeks of preparation and cleanup, so a huge amount of time would be saved.

"The crew is able to spend more time doing science and less time doing maintenance," said Richard Rembala, a chief engineer with MDA, the contractor that built the robot. "It completely frees up their time."

In addition to allowing astronauts to escape routine maintenance, the robot would be able to handle unexpected work.

"Now with Dextre, we'll actually be able to do repairs," Rey said.

Though it's 12 feet tall, Rey calls Dextre a robotic surgeon.

"Despite its large size, Dextre is designed to provide human-sized tasks," Rey said. "It can pick up objects from the size of a phone book to the size of a phone booth. These seven joints give Dextre the mobility it needs."

The robot arm also has delicate sensors that prevent too much pressure on bolts or fasteners. The electrical device is commanded with laptops and hand controllers, and it can be controlled from the ground.

"It can actually feel how hard it's pushing," Rey said. "It feels what it's doing and aids the operator."

The first of the arm's nine pieces went up on the Endeavour mission. The other eight pieces will go up on a mission in February. The robot will require spacewalking astronauts about
12 hours to assemble.

And while the machine has been designed to last for 15 years, its creators expect it to last much longer.

"I expect it will be decades," Rey said.

August 22nd 2007