Orbital Transfer Lab
Hohmann transfers, gravity assists and the Oberth effect you can fly in 3D, with real Kepler physics under every animation and replays of eight historic missions.
Pick two planets and watch the Δv budget, transfer time and phase angle play out; build a patched-conic slingshot; replay Voyager, Cassini, New Horizons or Parker Solar Probe against their real flyby dates. The physics is plain TypeScript with no React or Three.js imports, pinned to textbook values by unit tests.
It is also honest about scale. A ruler reads the distance the camera is actually looking at, and the exaggeration needed to see the planets at all is stated on screen. Switch it to true scale and they nearly vanish, which is the point.
TYPESCRIPT
REACT
THREE.JS
2026