A still from a video showing testing of an engineering model of the Curiosity rover shows a pattern of holes -- the "visual odometry markers" in the wheels, which leave a rhythmic pattern in the rover's tracks, which will help the rover determine how far it has traveled using optical navigation. If you're wondering why the pattern appears as it does, they are dots and dashes of Morse code. As the rover drives, it spells out "J-P-L." J: . - - - P: . - - . L: . - . .

NASA / JPL