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comets and asteroids are very

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fascinating places that may contain

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building blocks or the remnants of the

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building blocks of the solar system

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however to explore but they present a

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unique set of challenges there is the

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low gravity environment or microgravity

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as we call it for example a person here

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on earth would weigh as little as a

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paperclip on the surface of a comet

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so Rover Lake curiosity which is

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currently exploring Mars would actually

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only weigh a couple of kilograms it

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wouldn't be able to generate much

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traction and in fact as it turns its

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wheels it would probably just push

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itself away from the surface it's

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actually quite likely to end up rotating

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and landing upside down at which point

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it's ended the mission for the rover so

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in step together JPL and Stanford have

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been working on a totally different

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Rover concept that is well suited to

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these environments called Hedgehog

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instead of rolling around on wheels the

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Hedgehog design actually puts three fly

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wheels on the inside of a cube by

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spinning these flavors up very slowly

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and then very quickly applying a brake

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which transfers all the momentum from

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the fly wheels we were able to cause

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Hedgehog to either hop or tumble or

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perform small adjustments we've done

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many tests here on earth in gravity

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offloading test beds recently we've

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flown to Hedgehog prototypes on a zero-g

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aircraft in these tests we demonstrated

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that we would be able to perform on a

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comet or an asteroid Hedgehog doesn't

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have a right way up instead it can

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tumble over the surface and come to rest

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on any one of its phases and still work

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purposing the Rosetta mission has sent

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back lots of very fascinating images

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from the surface of Comet 67p and these

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images show us an incredibly rugged

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terrain including large sinkholes where

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a traditional Rover would get terribly

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stuck so we've even tested Hedgehog

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performing a type of escape maneuver

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where it spins itself up and does this

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tornado-like maneuver where it can

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actually launch itself vertically out of

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a sandpit

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in our future work we're looking at

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increasing their level autonomy giving

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the Hedgehog Rovers the ability to think

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for himself and to navigate from one

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point to another the Hedgehog Rovers

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ability to move around on the surface of

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comets and asteroids could enable a wide