Gravitational assist

The term gravitational assist (alternately gravitational boost or slingshot maneuver') refers to the technique of flying a space probe near a planet to boost its velocity.^[1]

During a close flyby with a planet a probe can transfer momentum, either gaining momentum, or losing momentum.^[1]

Voyager 1 and Voyager 2 relied on the gravitational assist technique, as they only had enough fuel to get as far as Planet Jupiter.^[1] Their close flybies of Jupiter were specifically designed to add momentum, anc change their orbits to point towards Planet Saturn.

References

↑ ^1.0 ^1.1 ^1.2 "Basics of Spaceflight: A Gravity Assist Primer". NASA Science. 2023-07-20. Archived from the original on 2026-07-02. Retrieved 2026-07-07. The two Voyager spacecraft provide a classic example. They were launched aboard a Titan-III/Centaur, with destinations of Saturn and beyond. But their launch vehicles could provide only enough energy to get them to Jupiter (halfway out to Saturn). Had Jupiter not been there at the right time, the spacecraft would have reached aphelion near Jupiter's orbital distance (about 5 AU or 750,000,000 km from the Sun). Their perihelion would have been around Earth's orbital distance (1 AU or 150,000,000 km), and they would have remained in that orbit until a planet or something else caused it to change.

[NASAScienceGravityAssist2023-07-20-1] 1.0 ^1.1 ^1.2 "Basics of Spaceflight: A Gravity Assist Primer". NASA Science. 2023-07-20. Archived from the original on 2026-07-02. Retrieved 2026-07-07. The two Voyager spacecraft provide a classic example. They were launched aboard a Titan-III/Centaur, with destinations of Saturn and beyond. But their launch vehicles could provide only enough energy to get them to Jupiter (halfway out to Saturn). Had Jupiter not been there at the right time, the spacecraft would have reached aphelion near Jupiter's orbital distance (about 5 AU or 750,000,000 km from the Sun). Their perihelion would have been around Earth's orbital distance (1 AU or 150,000,000 km), and they would have remained in that orbit until a planet or something else caused it to change.

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