Astronomy
Two spacecraft on a tether
Deploy a tether between two spacecraft. Watch gravity-gradient libration and see how reeling changes the angular motion and tension.

The model and its limits
Relative Hill dynamics of two equal masses and a unilateral massless cable. The powered reel changes length; slack endpoints move freely. Time is accelerated 60×. Display scale is uniform; slack cable curvature is illustrative. Cable bending waves and electrodynamics are omitted.
Equations used in the module
Equations x_ddot = 2 n y_dot + 3 n² x - T x/(mu r); y_ddot = -2 n x_dot - T y/(mu r); mu = m/2; T >= 0; r <= L


