Traditional probes exploring alien worlds such as Mars rover typically roll around on wheels and are not capable of operating upside down. The rough surface and low gravity that characterize small bodies such as comets and asteroids, however, make traditional maneuvers more hazardous.

Scientists have been eager to study and explore comets and asteroid as these are considered as the building block of planets but sending robotic missions to these worlds can be tricky such as what has been demonstrated by the European Space Agency's (ESA) Rosetta mission last year.

Although the Philae lander successfully landed on the surface of Comet 67P/Churyumov-Gerasimenko, the probe bounced twice and eventually rested in a less than ideal location. Because comets such as 67P have far weaker gravitational fields than that of the Earth's, the slightest unnecessary movement could spell disaster for the conventional robots.

Researchers from NASA's Jet Propulsion Laboratory, Massachusetts Institute of Technology and Stanford University appeared to have come up with a solution to this problem with the concept for a Hedgehog robot that is particularly designed to overcome the challenges of navigating in small bodies in the solar system.

"Hedgehog is a different kind of robot that would hop and tumble on the surface instead of rolling on wheels. It is shaped like a cube and can operate no matter which side it lands on," said Issa Nesnas, from NASA's JPL.

Two hedgehog prototypes, one that is covered in spikes acting as legs that can be used as probes for sampling the surface of comets and asteroids and another, a basic cube, were tested onboard NASA's C-9 aircraft research on microgravity in June.

The robots demonstrated several types of maneuvers in a wide range of surfaces from sandy to icy that could be useful when traversing small bodies with low gravity.

Benjamin Hockman, from Stanford University, said that they have experimented with a number of spike configurations and found that a cube shape offers the best hopping performance. He also noted that a cube structure is easier to manufacture and package with a spacecraft.

Researchers are now working on the autonomy of the robot trying to increase the number of things that the Hedgehog can do without instructions coming from Earth. The idea is that an orbiting mothership would transmit the signals to and from the robots in a similar manner that Curiosity and Opportunity communicate through satellites that orbit Mars.

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