Took quite a few lines of code to achieve this level of minimalism.

First usage of the Pause button AKA "Show-off toggle" - to show off new trajectories with landing points and less hardcoded "empirical constants".

Periapsis for non-elliptic trajectory, calculated for free while `unfoldr`ing momentum over time.

Orbiting 101

Prograde "forward" burn (blue): increase speed, raise/widen orbit and leave.

Retrograde "reverse" burn (red): slow down, lower/tighten orbit and fall on a body.

Burning at periapsis moves apoapsis (opposite point) directly towards/away wrt. planet center.

The orbiter always wants to crash onto something. So your goal is to miss the surface while falling at it.

With a healthy dose of existential quantification and runtime type reflection it is now possible to create delayed actions. And that, other than opening a hells gate into concurrency bugs, enables animation chains. Like this new warp-in effect I've always wanted.

Best of all, this doesn't contain any SpaceMar-specific code. And so it goes straight into apecs-gloss-starter game template.