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Landing on an asteroid is not exactly like landing on a comet — but it’s not far off. Both have highly irregular surfaces, and present all-new challenges to scientists looking to land a space robot from Earth. The European Space Agency’s partially failed Philae landing showed just how tough it can be, and how the relatively simple act of touchdown can present fatal problems in such an extreme environment. In that spirit, NASA’s latest concept for landing on an asteroid has been designed from the ground up for the specifics of its unusual mission. They’ve dubbed the radical new rover the Hedgehog.

The name derives from the Hedgehog’s mode of locomotion: tumbling. Rather than driving around with car-like wheels on the bottom and a human-like head on the top, Hedgehog is a roughly cube-shaped robot that has no particular up or down orientation. It’s designed to be impact resistant and, most importantly, it needs no particular exterior conditions to move. If there’s a shelf of rock blocking its way forward, it might be able to jump up and continue on; if it gets wedged in a crack in the process, it can probably launch itself right back out again. In the extremely low gravity of even the largest asteroids, Hedgehog could be quite the acrobat.

This 360 degree panorama taken by Philae shows that the little lander ended up in an awkward spot.

Hedgehog’s style of movement is made possibly by the three “fly wheels” that take up most of its internal space. Rather than rolling around on external wheels, the rover has three radially arranged wheels weighted at the rim. These wheels slowly spin up to a high speed, eventually carrying a lot of kinetic energy. Suddenly stopping these wheels transfers that rotational kinetic energy into directional kinetic energy — causing Hedgehog to move. By spin-stopping the three wheels simultaneously at different speeds, the rover can precisely control its movement and rotation for both large jumps and small positional adjustments.

One great thing about this method of locomotion is that it doesn’t matter the consistency of what you’re sitting on. Whether it’s on solid rock or super-fine regolith, the forces moving Hedgehog forward don’t require any real traction with the ground; assuming it could spin up a fly wheel fast enough, this system could even allow Hedgehog to adjust its path mid-air. They’ve given it a “tornado” special move, in which it jumps up and spins as violently as possible, probably as a last-resort measure should the rover become hopelessly stuck somewhere — or perhaps if it needs to blow a bunch of space dust off of an object of interest.

Most excitingly, the prototypes currently weigh around 11 pounds, though that will probably increase to 20 pounds or more when scientific instruments have been added in. Hedgehog is light, compact, and cheap enough that a Hedgehog-based mission could see the release of several of the little tumblers at once.  Since they’re so much more rugged than a normal rover, NASA feels comfortable giving the cubes some autonomy in getting around the asteroid when out of contact with Earth. A network of several Hedgehog cubes could do wide-ranging analysis of an asteroid quite quickly, compared to something like Curiosity.

It’s not a perfect design, however, since of course a rover has to do more than simply rove. Hedgehog does not have nearly as much internal space for instrumentation as a classical rover, and whatever it does carry has to be capable of enduring the forces caused by its tumbling, crashing movements around the asteroid’s surface.