I love these incredibly simple and elegant classic technologies. GPS is one of the best. It seems like it would be incredibly complicated and mysterious, but it's actually quite straightforward.

I'm working on a presentation now to explain how GPS works to second graders. If they understand it, I'll take some photos and do a write-up.

even though the concepts are straightforward, the implementation requires great care in order to maintain and extract the required precision. Throw that tech into space takes everything to an even higher level requiring radiation hardening, weight management, and long term reliability. You can't send repair crews to fix them if they break. As an engineer, I am in awe of those who design and build these things.