A Canadian-built robotic handyman fixed to the International Space Station has demonstrated that it can perform ultra precise tasks in space.
The robot, called Dextre, showed off its skills on a mock satellite attached to the International Space Station.
The mock satellite, designed and built by NASA's Goddard Space Flight Center, is about the size of a washing machine and has various caps, nozzles and valves like those found on satellites.
The robotic demonstration is part of the Robotic Refueling Mission (RRM), a collaboration between NASA and the Canadian Space Agency, designed to demonstrate the ability of robots to refuel and service existing satellites in space.
Dextre is a twin-armed robot, or telemanipulator, that is part of the Mobile Servicing System (MSS) on the International Space Station and represents part of Canada’s contribution to the orbiting laboratory.
The robotic demonstration took place March 7-9.
Dextre, whose name reflects the robot's dexterity, performed several tasks over the three day test. It showed it could retrieve tools and release launch locks on the mock satellite RRM module. Dextre also used a wire-cutter to sever razor thin wires that were fastening a mocked-up gas cap. The task might sound unimpressive but, for a 3 metre-tall robot suspended on the end of a 17 metre mechanical limb called Canadarm2, manipulating the wire with a clearance of about a millimetre, required extraordinary precision.
Artist's impression of Dextre's RRM tool preparing to cut wire. Credit: NASA
"The Robotic Refueling Mission required surgical precision and Dextre succeeded each task on the first attempt," said Steve MacLean, President of the Canadian Space Agency. "It's the robotic equivalent of threading a needle while standing on the end of a diving board. With thirty years of experience flowing through the iconic Canadarm, Canadarm2 and now Dextre, Canada has honed its skills in space robotics to millimetre precision."
Since the launch of Sputnik in 1957, satellites have been placed into space as disposable items, some have burned up in Earth’s atmosphere but most have simply run out of fuel and added their metallic corpses to the ever-growing orbital graveyard. There are believed to be 180 dead satellites orbiting around Earth.
Dextre is designed to put an end to this culture of floating junk by proving that robots can be used to refuel and service satellites in space. The ability to refuel satellites in space could one day save satellite operators from the significant costs of building and launching new replacement satellites. With over 1,000 active satellites currently operating in the near-Earth environment, the savings would be substantial.
The RRM module was taken to the ISS aboard the final space shuttle mission, STS-135 in July 2011.
Astronauts Mike Fossum and Ron Garan transferring the RRM module from the cargo bay of the Space Shuttle Atlantis on July 12, 2011. Credit: NASA
Dextre is operated remotely from Earth at the Canadian Space Agency’s (CSA) control room in Quebec. The robot was shipped into space in nine parts and was assembled by astronauts over a series of spacewalks in 2008.
So far, Dextre has passed the satellite refueling tests with flying colours and there are more tests planned in the next few months. Its next job will be to unscrew the mock-up satellite’s fuel cap and connect a fuel hose to a fuel valve.
Before a satellites leave the ground, they are filled with fuel and their tanks are sealed, covered and designed never to be accessed again – making Dextre’s job far from straightforward.
Assuming the robot passes those tests, it will be at least a year before it goes to work refueling real satellites. Until then, its main duty will be repairing the International Space Station while the astronauts on board are asleep – a bit like a giant robotic version of those elves that helped the shoemaker in the fairytale.