Orbital Mechanic — The Free Online Orbital Physics Game
Orbital Mechanic is a free physics game that teaches orbital velocity, Kepler's laws, and gravitational mechanics through 8 levels of satellite launch puzzles. Discover why satellites stay up — not by reading, but by doing.
How to play
- 1Click to set your launch point: Click anywhere near the planet surface. Your satellite launches from the point on the planet closest to your click.
- 2Drag to set velocity: Drag away from your launch point. Drag direction sets velocity direction — drag distance sets speed.
- 3Find stable orbit: When your satellite enters the target orbit band (shown as a cyan ring), a progress arc appears. Hold the orbit for 3.5 seconds to achieve it.
- 4Watch for crashes and escapes: Too little velocity and you crash into the planet. Too much and you escape into space. The sweet spot is orbital velocity.
- 5Earn stars: Fewer launches = more stars. Par is shown per level — 3 stars means you matched or beat par.
The physics behind the game
Orbital velocity
For a circular orbit, gravity must exactly provide the centripetal force. This gives a single unique speed at every radius — too fast and the satellite spirals out, too slow and it falls inward.
Kepler's third law
The orbital period scales with r^(3/2). Double the orbital radius and the period increases by 2^(3/2) ≈ 2.83×. This is why geostationary satellites must orbit at a specific altitude.
Escape velocity
Escape velocity is exactly √2 times the circular orbital velocity at the same radius. Launch faster than this and your satellite never returns.
Gravitational potential energy
Orbital energy is always negative — the satellite is bound to the planet. As radius increases, energy increases (becomes less negative) and orbital velocity decreases.