Geostationary Longitude Drift & East-West Station-Keeping

Geostationary satellites appear fixed over one point on Earth, but they are not truly at rest: Earth's slightly triaxial equatorial gravity field creates two stable "wells" and two unstable ridges around the GEO ring, and any satellite not parked exactly on a well slowly drifts, librating like a pendulum with a period of roughly two years. This simulator renders that potential landscape as a real 3D terrain around a scaled Earth-and-orbit model, integrates the satellite's longitude with the governing pendulum equation, and lets you switch on East-West station-keeping — small tangential thruster burns that reverse the drift whenever the satellite reaches the edge of its assigned deadband box. Live telemetry tracks longitude, drift rate and the cumulative delta-V spent holding the slot, with the delta-V computed from the same tangential-impulse relation real mission planners use.