Since 2012 morse code (also known as CW for the mode of operation) has been making an ‘impact’ on the Mars surface. There is an actual functional reason as to why as well, checkout the link below for full details.
The Jet Propulsion Laboratory engineers behind the Mars Curiosity rover figured out how to mark the Martian territory with the letters JPL, just in case little green (or any color) men (or women) want to know who they’re dealing with.
They needed holes in the wheel tracks to help shed sand, dirt, and mud, so why not have holes that mean something? I think I would have chosen different code than a company name, but I guess they built it.
https://www.businessinsider.com/curiosity-rover-wheels-hidden-secret-morse-code-2016-2
For more information on how to learn and copy Morse code, check out https://www.w1opr.us/morse-code