Disclaimer: Beginner experimental tool — results may not be accurate. For educational use only.
What is the Vis-Viva Equation? (Click to expand)▼
The Vis-Viva Equation is a simple but powerful formula used in orbital mechanics to calculate a spacecraft’s speed at any point in its orbit.
Formula: v = √[μ (2/r − 1/a)]
• v = orbital velocity (speed) • μ = gravitational parameter of the central body (how "heavy" the planet is) • r = current distance from the center of the planet • a = semi-major axis (average size of the orbit)
Key Facts: • The satellite moves **fastest** at periapsis (closest point) • The satellite moves **slowest** at apoapsis (farthest point) • Moving the True Anomaly slider lets you see the speed at any location along the orbit.
This is one of the most important equations in real spaceflight.
