The ailing Spirit Rover - already a four-year veteran of Mars exploration - is now limping backwards over the red planet. One of Rover’s front wheels is gone gammy, hopelessly stuck. But, lo and behold! The unmoving wheel is dragging a trail through the crust of Mars, revealing layers of silica and traces of titanium. These elements are common around fumaroles and are typical breeding grounds for extremophile life forms. YOU GO, ROVER!