NASA's Curiosity rover has been on Mars for over a year now, and in the time has traversed nearly three miles. While its wheels are made of high-grade aluminum, they're not strong enough to last forever. NASA this week it was taking an extra-long look at the wheels, and boy are they in rough shape.

Dents and holes are to be expected after a bit of time driving on the surface of another planet, but the wear-and-tear has accelerated lately and NASA's not sure why. To examine the damage, they've taken a few beautiful shots of Curiosity's six wheels, and you can really see what rough terrain does to the average space-faring probe. It looks like Curiosity's been through the .

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As you can see in the below, some of the dents haven't quite punched clean through yet, but they're on their way:

And this is what the wheels looked like when (relatively) shiny and new:

And I just thought this was really cool, so enjoy:

Even in rough shape, the cosmos and the human engineering that gets us there is incredibly beautiful.

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Photos credit NASA-JPL