Looks like at least one of the rovers is really starting to show its age:

The front right wheel of NASA's Spirit rover has stopped working – just as the approaching Martian winter means it is increasingly urgent that it gets to a northerly facing slope, to maximise the sunlight falling on its solar arrays.

I just can't get the image of a golf-cart-sized robot dragging itself across the sand grumbling in a tiny electronic voice, "more brainssss!!!" I think I've been hanging around Joshua too much.