Really cool!

I've been meaning to implement SGP4 from scratch as a learning exercise. What I found really interesting is how the USAF/NORAD tracks and reports objects in LEO: they publish Two-line Element Sets (TLEs), which are a fixed-width ASCII format derived from punch cards.[1] The format is pretty easy to parse.[2]

[1]: https://en.wikipedia.org/wiki/Two-line_element_set [2]: https://www.celestrak.com/NORAD/documentation/tle-fmt.php [3]: https://www.celestrak.com/NORAD/documentation/checksum.php