Home▸Space & Astronomy▸Gravity Assist: How Spacecraft Steal Momentum from Planets

🚀 Gravity Assist: How Spacecraft Steal Momentum from Planets

Interactive 3D solar-system flyby where aiming a simulated spacecraft's trajectory past a planet shows its speed and heading changing from a gravity-assist slingshot manoeuvre.

Space & Astronomy3DModerate60 FPS

A spacecraft on a hyperbolic path swings past a moving planet, and the encounter genuinely bends its trajectory and shifts its Sun-relative speed — computed live from real two-body gravity rather than a scripted animation.

🔬 What It Demonstrates

Relative to the planet, incoming and outgoing speed are equal — only direction changes. But because the planet is itself orbiting the Sun, adding its velocity back in can raise or lower the spacecraft's heliocentric speed.

🎮 How to Use

Set the approach speed, aim distance and target planet, choose whether to pass behind or in front of the planet's motion, then launch the flyby and watch the speed and turn-angle readouts update.

💡 Did You Know?

Voyager 2's tour of all four giant planets relied on a rare alignment that let each gravity assist set up the next — an opportunity that will not recur for well over a century.

⚙ Under the hood

Interactive 3D solar-system flyby where aiming a simulated spacecraft's trajectory past a planet shows its speed and heading changing from a gravity-assist slingshot manoeuvre.

gravity-assistspacecraft-trajectoriesorbital-mechanicsspace-navigationastronomy

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install