@ross Play #KerbalSpaceProgram for a while, you'll get a much better understanding of the (very counterintuitive) nature of #OrbitalDynamics :)

Oh, and how did they calculate things in the #1960s? While final trajectories were analyzed with (compute-intensive) #NBodySimulations, rough trajectories were created with "#PatchedConics", which basically sort of converts a trajectory into a #geometry problem.