Megaconstellation Drag Decay & Station-Keeping

Very-low-Earth-orbit megaconstellations like Starlink fly low enough — 300 to 600 km — that residual atmospheric drag is not negligible: it steadily steals orbital energy, and every satellite in the shell is either decaying toward re-entry or burning propellant to stay put. This simulator models that trade with a real first-order drag-decay equation and an exponential thermosphere density profile, letting you tune the shell's starting altitude, the solar-activity state that inflates or deflates atmospheric density, and each satellite's area-to-mass ratio. Toggle station-keeping on to watch a Hall-effect-thruster-style burn hold the shell in place while the panel tallies the delta-v and propellant mass that costs, or toggle it off and watch the shell sink — slowly at first, then in a runaway — until it re-enters.