In addition to the 19 grousers that go around the wheel, each wheel also has an odometry feature, which is a section of the wheel that has a pattern of holes in it. These holes help the rover visually track its progress, and they also spell out “JPL” in Morse code, because why not.
From the article:
Love nerds! That’s so cool
JPL wanted to use the letters J - P - L in the wheel design, but NASA said no, so they added the Morse code and got away with it. Nerd Rule :)
Even better! Great story thanks for sharing
Forgot to add… The only part of the wheel not to get damaged was the section with the Morse code!