Here's the daily grind! The Spirit rover has made a round, shallow depression in a rock called Adirondack. By using a Rock Abrasion Tool (RAT) history's first grinding of a rock on Mars was done on February 6, 2004. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. Image credit: NASA/JPL/Cornell
