Lagrange

empty space has addresses. park in one.

drop probes in a two-body field — five points let you park

Around two orbiting bodies, gravity and motion almost always pull anything you place there away — drift is the default, not stillness. Only five spots hold something in place, exactly where those forces cancel, which is why real spacecraft and asteroids actually sit at them instead of drifting off.

Concepts: orbits, gravity.

An interactive you play with one thumb, on Wundr.