We have seen for the last several years that cart-like robotic rovers are ideal for traversing planets like Mars.
But physics makes it practically impossible for such vehicles to travel on smaller bodies like asteroids and comets.
NASA’s Jet Propulsion Laboratory in Pasadena, California, Stanford University in California and Massachusetts Institute of Technology in Boston, Massachusetts have partnered to develop a new concept rover called Hedgehog. This particular version of a rover is supposed to be ideal for traveling over the rough, rocky surfaces one would find on an asteroid or comet.
Called Hedgehog, this particular robot has no wheels and hops and tumbles on a surface. It is shaped like a cube and can operate no matter which side it lands on, explained Issa Nesnas, leader of the JPL team.
Spikes on the cube move due to spinning and braking internal flywheels. The spikes protect the robot’s body from the terrain and act like feet while hopping and tumbling.
Nesnas added that the spikes could include instruments such as thermal probes so they can take the temperature of the surface as the robot tumbles.
There are two prototypes – one from Stanford and the other from JPL. Both were tested onboard NASA’s C-9 aircraft for microgravity research in June 2015. During 180 parabolas maneuvers during a total of four flights, these robots demonstrated several types of maneuvers that would be useful for getting around on small bodies with reduced gravity. Researchers tested these maneuvers on different materials that mimic a wide range of surfaces including sand, rough and rocky, slippery and icy, and soft and crumbly.
On one of the test flights on the C-9 aircraft the Hedgehog demonstrated that it could perform a “tornado-like” maneuver, in which the robot aggressively spins to launch itself from the surface. This maneuver would be ideal for escaping sandy sinkholes or other conditions in which the robot would be stuck.
The JPL version of the device has eight spikes and three flywheels and weighs about 11 pounds (5 kilograms). Researchers say that it could weigh more than 20 pounds (9 kilograms) if packed with instruments like cameras and spectrometers. The Stanford prototype is slightly smaller and lighter and has shorter spikes.
Researchers are currently working on the Hedgehog’s autonomy, trying to increase how much the robot can do on its own without instructions from Earth. The idea is that an orbiting mother ship could relay signals to and from the robot and help it navigate and determine its position.
The construction of a Hedgehog rover is relatively low-cost compared to a traditional rover, and several could be packaged together for flight. A mother ship could release many robots at once or in stages, spreading them out to make discoveries.
The device is in Phase II development through the NASA Innovative Advanced Concepts (NIAC) Program. NASA’s Center Innovation Fund (CIF) and NASA’s Flight Opportunities Program (FOP) supported the tests. NIAC, CIF and FOP are programs in NASA’s Space Technology Mission Directorate, headquartered in Washington, D.C. The California Institute of Technology manages JPL for NASA.