NASA's Mars rover Curiosity used a new technique, with added autonomy for the rover, in placement of the tool-bearing turret on its robotic arm during the 399th Martian day, or sol, of the mission. This image from the rover's front Hazard Avoidance Camera (Hazcam) on that sol shows the position of the turret during that process, with the Alpha Particle X-ray Spectrometer (APXS) instrument placed close to the target rock. Credit: NASA/JPL-Caltech