You can't take a spin on Mars without getting dirty.
The photo mosaic above shows three of the six wheels on NASA's Curiosity rover, already dusted with Mars dirt after just a month on the Red Planet. Curiosity snapped the shots of its wheels and underbelly using the Mars Hand Lens Imager (MAHLI) on the end of the rover’s 2.1-meter robotic arm. MAHLI took the mosaic photos September 9, during a weeklong checkout of the robotic arm's functions.
The cutouts visible in Curiosity's wheels are used to estimate distance traveled by a process called visual odometry. (The cutouts also spell out "JPL" in Morse code in honor of the Jet Propulsion Laboratory in Pasadena, Calif., which manages the rover mission for NASA.)
Having worked out its robotic arm, Curiosity will soon proceed toward its first destination, a region about 400 meters distant called Glenelg, where multiple terrain types meet. The rover's ultimate destination, the much more distant Mount Sharp, rises in the background on the right side of this MAHLI mosaic.