Gravitational Slingshot Sandbox

Simulation Mode

Single Planet Flyby Earth-Moon (3-Body)

Mission Presets

Horizontal Offset (Z) 0 km

Vertical Offset (Y) 0 km

Initial Velocity (V_in) 10.0 km/s

Planet Mass (10²⁴ kg) 5.97 x10²⁴ kg

Planet Speed (km/s) 0.0 km/s

Simulation Speed 1.00 hr/s

Moon Start Angle 44.1°

Launch Altitude 400 km

Mission Telemetry

Live Speed (V) 0.00 km/s

                        ΔV Boost
                        +0.00 km/s
                    

Planet Speed 2.00 km/s

Closest Approach -- km

Gravity Assist Mechanics

A Gravitational Slingshot (or Gravity Assist) involves a spacecraft flying close to a massive planet. While energy is conserved in the planet's reference frame (the probe leaves at the same speed it arrived), in the Sun's reference frame, the planet is moving.

As the probe falls into the gravity well, it gets dragged along by the planet's orbital momentum. If it flies *behind* the planet (relative to its orbit), it steals some of the planet's kinetic energy, achieving an immense velocity boost (up to V_out ≈ V_in + 2V_planet).