By William Cameron III
Like the prop of a science-fiction movie, a milk-crate-sized robot rests motionless inside a test container aboard a Zero-G aircraft.
The cube-shaped object suddenly springs from its inanimate state, launching into a tornado-like spin through the air unaided by tires, propellers, jets or wings.
The object spinning itself inside NASA’s C-9 aircraft demonstrates the movement freedom of a new comet-exploration robot.
According to a press release on NASA’s Jet Propulsion Laboratory (JPL) website, the self-projecting device comes courtesy of a joint effort between JPL in Pasadena, Calif.; Stanford University in Stanford, Calif.; and the Massachusetts Institute of Technology in Cambridge.
Creators dub the prototype “Hedgehog” for the spike-like structures protruding from its corners.
The spikes guard the robot body from direct contact with harsh terrain, and “could also house instruments such as thermal probes to take the temperature of the surface as the robot tumbles,” said JPL team leader Issa Nesnas.
The deviation from traditional design addresses obstacles encountered by the Philae lander during the European Space Agency’s Rosetta mission.
Microgravity conditions present a challenge to rover wheels rolling over a comet’s uneven surface.
Low gravity prevents wheels from gaining traction, and reduces the weight of a 200 pound rover to little more than that of a paperclip.
A conventional rover or lander that gets stuck in rough terrain becomes inoperable, as the Philae lander experienced.
The novelty of Hedgehog’s design allows it to “operate no matter which side it lands on,” as Nesnas notes.
Hedgehog’s method of travel literally reinvents the wheel, replacing the surface-rolling wheels of a traditional rover with a set of three internal flywheels.
These motorized flywheels accelerate and stop rapidly inside the cube-shaped frame, using the force of braking to throw the device in a desired direction.
Adjustments to the speed and intervals of each wheel control the trajectory of the motion generated.
In addition to advanced maneuverability, Hedgehog’s construction offers a more cost- and size-effective.
The JPL press release also describes a vision of multiple hedgehogs, rolling like a game of dice across a comet surface: “the mothership could release many robots at once or in stages, letting them spread out to make discoveries on a world never traversed before.”
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