Exploring an asteroid, comet or a small moon like Mars' Phobos isn’t easy. We can’t send a rover like Curiosity, because there just isn’t enough gravity for it to wheel across the surface. But what if we sent something much lighter and smaller?
That’s what one team of scientists is proposing with a cube-shaped robot they have called Hedgehog. The vehicle wouldn’t use wheels; instead, it would propel itself by spinning disc-shaped flywheels in its interior. Rotating them at high speeds and then suddenly stopping them, the cube-shaped robot can send itself tumbling across the surface. And it can even perform precise maneuvers with the technique.
The research is a joint effort between NASA’s Jet Propulsion Laboratory (JPL), Stanford University in California, and the Massachusetts Institute of Technology (MIT).
"Hedgehog is a different kind of robot that would hop and tumble on the surface instead of rolling on wheels," said Issa Nesnas, leader of the JPL team, in a statement. "It is shaped like a cube and can operate no matter which side it lands on."
Hedgehog would weigh about 9 kilograms (20 pounds). Spikes dotted around the cube would protect its body and also allow it to grip onto the surface. In its casing, it could have a number of cameras and instruments to study the surface of a comet or asteroid, and thanks to its “hopping” technique, it could explore vast regions. Its cube shape also makes it ideal to be carried by a larger spacecraft to a destination.
The robot can even get itself out of a tight situation. As seen on Comet 67P, there are a number of sinkholes that could pose a problem to robotic explorers. But Hedgehog can perform a “tornado” maneuver, where it rapidly spins itself to move up and out of a hole.
Above is a video explanation of Hedgehog. NASA.
The project is being funded through the NASA Innovative Advanced Concepts (NIAC) program. The team envisages that Hedgehog could even be autonomous, hopping its way across a celestial body and relaying information to a spacecraft in orbit.
Various tests were performed with Hedgehog prototypes recently, including in the simulated low-gravity environment on NASA’s C-9 aircraft, which makes looping flights to induce microgravity for a short period of time.
While Hedgehog hasn’t been formally picked for a mission yet, who knows; maybe it’ll be coming to an asteroid or comet near you soon.