English: NASA's Mars rover Curiosity cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple. The rover's right Navigation camera took this image of the scuff mark on the mission's 57th Martian day, or sol (Oct. 3, 2012), the same sol that a wheel created the mark. For scale, the width of the wheel track is about 16 inches (40 centimeters).