The slingshot effect alters a spacecraft's trajectory and velocity by flying it close to a massive celestial body. As the probe falls into the planet's gravity well, it steals a tiny fraction of the planet's orbital momentum, resulting in a massive boost in speed relative to the Sun without expending propellant. This technique is essential for sending probes to the outer solar system.
Heard on the job
Voyager 2 used the slingshot effect at Jupiter to gain enough velocity to reach Saturn.
Insider tip
While it feels like free energy, the maneuver actually slows down the planet's orbit by an infinitesimally small amount to conserve momentum.
Also heard as
- gravity assist
- swing-by