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gravity assist
gravity assist The technique of using the gravitational field and orbital velocity of a planet to alter a spacecraft's trajectory and velocity; also known as a gravitational slingshot. As the spacecraft makes a close fly-by of a planet, its direction of travel is altered and it picks up additional speed from the planet's orbital velocity. The technique was first used by Mariner 10, which flew past Venus on its way to Mercury in 1974. The two Voyager probes made fly-bys of Jupiter, considerably shortening the time they took to reach Saturn. Voyager 2 subsequently used gravity assists from Saturn and Uranus to take it to Neptune. Other probes to use gravity assists were Giotto, Galileo, and Ulysses.
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"gravity assist." A Dictionary of Astronomy. 1997. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "gravity assist." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O80-gravityassist.html "gravity assist." A Dictionary of Astronomy. 1997. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-gravityassist.html |
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gravity assist
gravity assist A technique used to accelerate or slow spacecraft without consuming fuel by transferring angular momentum from a planet to the spacecraft. The craft approaches the planet, is accelerated towards it by gravitational force, and as it leaves decelerates to its original speed relative to the planet, but not relative to the Sun. If a spacecraft approaches from behind, travelling in the same direction as the planet, it will accelerate relative to the Sun by acquiring angular momentum; if it approaches from ahead, travelling in the opposite direction to the planet, it will slow relative to the Sun by losing angular momentum to the planet.
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Cite this article
AILSA ALLABY and MICHAEL ALLABY. "gravity assist." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "gravity assist." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O13-gravityassist.html AILSA ALLABY and MICHAEL ALLABY. "gravity assist." A Dictionary of Earth Sciences. 1999. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-gravityassist.html |
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