Gravity assist Animation of Voyager 1's trajectory from 5 September 1977 to 30 December 1981 Voyager 1· Earth· Jupiter· Saturn· Sun A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby which makes use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft, typically to save propellant and reduce expense. Gravity assistance can be used to accelerate a spacecraft, that is, to increase or decrease its speed or redirect its path. The "assist" is provided by the motion of the gravitating body as it pulls on the spacecraft. Any gain or loss of kinetic energy and linear momentum by a passing spacecraft is correspondingly lost or gained by the gravitational body, in accordance with Newton's Third Law. The gravity assist maneuver was first used in 1959 when the Soviet probe Luna 3 photographed the far side of Earth's Moon, and it was used by interplanetary probes from Mariner 10 onward, including the two Voyager probes' notable flybys of Jupiter and Saturn. ## Explanation Example encounter.In the plane

nt and Test Facility Prepares Artemis Hardware for Moon article 4 days ago Highlights 11 min read La NASA anuncia la cobertura de la misión lunar Artemis II article 5 months ago 15 min read Agenda diaria de la misión a la Luna de Artemis II de la NASA article 5 months ago 6 min read La NASA refuerza Artemis: añade una misión y perfecciona su arquitectura general article 5 months ago Explore This Section Basics of Spaceflight: A Gravity Assist Primer A Gravity Assist Primer The "gravity assist" concept has proven fundamental to exploring our "back yard" — the solar system. The technique has even been employed at least once to rescue an Earth-orbiting communications satellite whose launch vehicle failed to place it in its intended geosynchronous orbit. Some History Several robotic spacecraft have used the "gravity assist" technique to achieve their targets "high up" in the Sun's gravity well. Voyager 2 launched in August 1977 and flew by Jupiter for reconnaissance, and for a trajectory boost to Saturn. Voyager 1 launched the following month and did the same (reaching Jupiter before Voyager 2 did). Voyager 2 then obtained an assist from Saturn and another one later from Uranus, climbing all the way to Neptune and beyond. Galileo took one kick from Venus and two from Earth, while orbiting the Sun en route to its destination, Jupiter. Cassini took two boosts from Venus, one from Earth, and another from Jupiter to gain enough momentum to reach Saturn. If you find any terms here you don't understand, see the Glossary on Basics of Space Flight , where you can look them up. Here's Chapter 4 , where Gravity Assist, and other trajectories are covered in a little more detail and broader perspective. The "gravity assist" flyby technique can add or subtract momentum to increase or decrease the energy of a spacecraft's orbit. Generally it has been used in solar orbit, to increase a spacecraft's velocity and propel it outward in the solar system, much farther away from the Sun than