Spin-Stabilized Solar Sail Deployment

A boom-less solar sail like IKAROS cannot unfold with rigid struts — it relies on centrifugal force. The spacecraft spins up while the membrane is still folded, then releases four corner tip masses that reel outward on tethers, pulling the sail taut into a flat square one triangular panel at a time. This simulator models that deployment as a real angular-momentum-conservation problem: with no external torque acting, L = I(r)·ω stays constant as the moment of inertia I(r) grows with boom radius, forcing the spin rate to fall exactly as a figure skater's does when extending their arms. Adjust the initial spin rate, tip mass, sail areal density and reel-out speed, watch the membrane unfurl in 3D, and track the live spin-down against the conserved angular momentum.