Rock analysis on Mars. Robotic arm of the Mars Exploration Rover Spirit, about to begin grinding the rock 'Adirondack'. Spirit landed on Mars on 4 January 2004. The instrument deployment device (IDD) is a retractable 'arm', which carries tools for preparing and analysing rock samples. The rock abrasion tool (RAT, centre left) exposes new layers of rock for examination by the microscopic imager (lower left), and the Mossbauer and Alpha- Particle-X-ray spectrometers (not seen). Such investigations may reveal how the rock was formed and whether this region of the Martian surface was once covered in water. Spirit successfully ground a hole in the rock's surface on 6 February 2004.