Robot built to climb alien cliffs
An agile robot is being groomed to scale volcanic cliffs on Mars, climb down sheer crater walls on the Moon, and traverse the craggy faces of asteroids.
For as much progress as the Mars Explorer Robots have made on the Red Planet, they have yet to collect samples from vertical cliffs and sheer crater walls, which contain clues to the planet's past.
That job may one day go to NASA's Lemur IIb, an evolved version of a crawling robot named Lemur.
"In general, all of these steep terrain features are of extreme geological interest," says staff engineer Brett Kennedy, principal investigator of the project at the NASA Jet Propulsion Laboratory in Pasadena, California.
Kennedy's team hopes to build a robotic system that can arrive at the base or the top of a steep feature and explore it the way a human being might, by climbing it.
The spider-like Lemur IIb has a disc-shaped body about 30 centimetres in diameter, four arm-like limbs about 15 centimetres long with peg-like tips, tactile sensors in the limb tips, and a motion planning computer system that gives the robot the untethered freedom to scale vertical surfaces.
Lemur IIb moves one limb at time, supporting its weight on three, while feeling for a hold with the fourth. Tactile sensors in the limb tips help the robot locate bumps in the 'road'.
A computer program used in the Mars Rovers is used in the Lemur to recognise the features as potential holds.
At the climbing gym
In separate tests conducted on a plywood wall with gym-style climbing holds, Lemur IIb used the tactile sensors located in the tip of its limb to identify holds; chose holds that offered the best support; and took small steps from one hold to the next, according to Kennedy.
Kennedy is considering replacing the peg-like tips with drill bits that would allow the robot to drill its own holds into a rocky precipice and at the same retrieve a core sample.
"I think it's a good idea if they can implement the hardware," says Dennis Hong, an assistant professor at Virginia Polytechnic Institute and a specialist in robot locomotion.
But he cautioned that although drilling may make the motion planning simpler, it could introduce new kinds of forces that might destabilise the cliff-hugging robot.
Kennedy and his team have a long time to work out the kinks. Even under the best funding and research, a cliff-climbing robot might not see interplanetary time for another 10 years.