 Today is September 21st, 2012, and I've been at JPL working on the NASA mission to Mars, the Curiosity rover. So today is a special day because the space shuttle was flying over and was doing a loop around JPL. So a bunch of us went up to the Mars Yard, and there the rover drivers brought out the Curiosity ScarePro rover, which is the one they used to test the mobility of the rover to understand how we can drive it on Mars. So the ScarePro rover came out to watch Endeavour. So this is the Mars Yard, and you can see that they have lots of big rocks around. And the idea is they use this rover with a suspension system that's similar to the wheel rover Curiosity. It's weighted differently. They count for the difference in gravity between Earth and Mars. But the rover drivers get to drive the ScarePro over all sorts of rocks and pointy objects to see how it behaves, how much it can tilt and still work, what happens when a wheel is suspended above the ground or caught up on a pointy rock. These tests give the rover drivers a good idea of how the rover on Mars will behave. So in this particular case, they're controlling the ScarePro rover with a joystick and a little control pad. However, the real rover on Mars gets sent computer commands well before it actually starts to drive. And so the rover planners do two things, one of which is evaluate the landscape and pick a path for the rover to drive. And they choose a path based on their knowledge of how it should behave, and obviously they try not to go over big rocks if they can go around them. Once the rover has gone outside of the zone where the rover drivers have a good 3D model, the rover can use autonomous software to pick its own path. One of the challenges with that is that sometimes the wheel slips and the center wheel on the right here is starting to slip. That's a teeny little bit about driving on Mars. Thanks for watching.