This 3D simulator lets you design a Walker Delta satellite constellation — the same mathematical scheme behind real megaconstellations like Starlink. Satellites are distributed across evenly spaced orbital planes around a rotating Earth, and you can watch coverage footprints sweep the globe as the constellation orbits in real time, driven by actual Keplerian orbital mechanics rather than a simplified animation loop.
A Walker Delta constellation is described by T/P/F: T total satellites spread across P orbital planes (each separated by 360°/P in RAAN — right ascension of the ascending node), with a phasing factor F offsetting the in-plane satellite positions between adjacent planes. The simulation computes each satellite's true Keplerian orbital position and renders coverage cones showing which parts of Earth each satellite can currently see.
Adjust Planes (P) and Sats/plane to change the constellation's size and structure, Inclination to tilt the orbital planes relative to the equator, and Altitude to raise or lower the orbits. Toggle "Show orbital planes," "Show coverage" and "Show grid" to change what's rendered, use Speed to fast-forward time, and Pause/Run to freeze the simulation for inspection. Drag to rotate the camera and scroll to zoom.
Starlink's operational shells sit near 53° inclination at roughly 550 km altitude — a deliberate choice, not an accident: that inclination gives strong coverage across the mid-latitude bands where most of the world's population and internet demand actually live, at the cost of weaker coverage right at the poles.
T is the total number of satellites, P is the number of orbital planes they're spread across (with T/P satellites per plane), and F is a phasing factor from 0 to P-1 that offsets each plane's satellites relative to its neighbours so that satellites don't all line up at the same in-plane angle simultaneously, giving more even global coverage.
Inclination sets the maximum latitude a satellite's ground track can reach — a 53° inclination orbit never passes directly over regions poleward of 53° latitude. Lower inclinations concentrate coverage near the equator; higher inclinations (near 90°, polar orbits) spread coverage more evenly toward the poles at the cost of density near the equator.
Higher altitude increases each satellite's field of view (so fewer satellites are needed for the same ground coverage) but also increases orbital period, per Kepler's third law, and increases signal latency. Low Earth orbit constellations like Starlink choose low altitude for low latency, accepting they need many more satellites and planes to maintain continuous coverage.
RAAN (right ascension of the ascending node) sets where each orbital plane crosses the equator. Spacing P planes evenly by 360°/P in RAAN ensures the planes are spread uniformly around the globe rather than bunching together, which is essential for uniform worldwide coverage rather than repeated overlapping ground tracks.
Each footprint shows the region of Earth's surface currently within line-of-sight of that satellite, based on its altitude and a minimum elevation angle above the horizon. As satellites move along their orbits, these footprints sweep across the globe, and overlapping footprints from multiple satellites indicate zones with redundant coverage.