This answer taught me about J002E3, an object detected in Earth orbit in 2002 that is assumed to be the Saturn V IV-B stage from Apollo 12. It's trajectory through space is fascinating:
This announcement explains that the trajectory of the object has been propagated backwards in time to conclude it is most likely the IV-B stage from Apollo 12.
This made me wonder: is the trajectory of J002E3 available? Ideally I'd hope to see:
- historic measurement data from 1969
- actual observational data from 2002 to now
- simulated datapoints for in between (or: would an amateur like myself be able to simulate this from #1 and/or #2?)
(This answer explains that the trajectory looks funky in part by the choice of reference frame in the animation - I'd be really curious to see the trajectory in different frames.)