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

The name derives from the Hedgehog'south mode of locomotion: tumbling. Rather than driving around with car-like wheels on the lesser and a human being-similar caput on the superlative, Hedgehog is a roughly cube-shaped robot that has no particular up or downwards orientation. It'due south designed to be impact resistant and, most importantly, it needs no particular exterior conditions to movement. If there'due south a shelf of rock blocking its manner forward, it might exist able to jump up and continue on; if it gets wedged in a crack in the process, information technology can probably launch itself right back out again. In the extremely depression 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.

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

Hedgehog'due south fashion of motion is made peradventure by the 3 "fly wheels" that have 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 upwardly to a high speed, eventually carrying a lot of kinetic energy. Suddenly stopping these wheels transfers that rotational kinetic free energy into directional kinetic energy — causing Hedgehog to move. Past spin-stopping the three wheels simultaneously at unlike speeds, the rover tin precisely command its motion and rotation for both big jumps and small positional adjustments.

One bully thing almost this method of locomotion is that it doesn't matter the consistency of what you lot're sitting on. Whether information technology'due south on solid rock or super-fine regolith, the forces moving Hedgehog forrad don't require any real traction with the ground; assuming it could spin upwards a fly wheel fast enough, this organization could even permit Hedgehog to adjust its path mid-air. They've given information technology a "tornado" special move, in which information technology jumps up and spins as violently as possible, probably as a concluding-resort mensurate should the rover become hopelessly stuck somewhere — or perhaps if information technology needs to blow a agglomeration of space dust off of an object of interest.

Most excitingly, the prototypes currently counterbalance around xi pounds, though that will probably increase to twenty pounds or more when scientific instruments have been added in. Hedgehog is calorie-free, compact, and cheap enough that a Hedgehog-based mission could run into the release of several of the piffling tumblers at in one case.  Since they're then much more rugged than a normal rover, NASA feels comfy giving the cubes some autonomy in getting around the asteroid when out of contact with World. 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, nonetheless, since of form a rover has to do more merely rove. Hedgehog does not accept nearly as much internal infinite for instrumentation as a classical rover, and whatsoever it does comport has to be capable of indelible the forces caused past its tumbling, crashing movements around the asteroid's surface.