gravity assist


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gravity assist

An astronautical technique whereby a spacecraft takes up a tiny fraction of the orbital energy of a planet that it is flying past, allowing it to change direction and speed. It has been used, for example, in the Voyager and Ulysses missions.
References in periodicals archive ?
The Earth flyby gravity assist increases the spacecraft's speed relative to the Sun from 78,000 miles (126,000 kilometers) per hour to 87,000 miles (140,000 kilometers) per hour.
It was the first mission to use gravity assist, flying by Venus on 5 February 1974 enroute to Mercury, where it arrived on 29 March.
Spacecraft using gravity assist save on fuel and have more room for instruments--important for Cassini, which will spend four years investigating Saturn and its moons.
5 years making extensive use of gravity assist manoeuvres (in order to save fuel and energy) around the Earth, Venus and Mars before reaching the Jovian system.
After the Mars gravity assist, Rosetta's perihelion will drop until it reaches the orbit of Venus, but before the probe comes that close to the Sun, another Earth flyby will send it out of the ecliptic plane.
The Hoist Vac, equipped with fender mounted water tanks, combines VacStar's pressurized discharge with a gravity assist.
It will then pass by asteroid Otawara in July 2006 and complete another Earth gravity assist in November 2007.
The spacecraft will fly by Jupiter for a gravity assist in February 2007.
The first half of its journey has been simply to set up this gravity assist with Earth.
It has used several gravity assist maneuvers - three from Earth and one from Mars - to gain the necessary momentum, refine its trajectory and match the orbit of the comet once it reaches the outer Solar System.
After swinging back around Earth for a gravity assist in early 1998, NEAR should meet the near-Earth asteroid 433 Eros a year later and orbit the rocky body for 11 months.
Launched from Earth on October 15, 1997, Cassini first swept past Venus in April 1998 at a distance of 284 km and used a gravity assist to give its orbit an aphelion of 1.