the.com/gravity assist
stealing a planet's momentum to fling spacecraft across the solar system for free
means A maneuver in which a spacecraft swings close to a planet or moon, using that body's motion and gravity to change its speed and direction without burning fuel.
from A compound of plain English parts. 'Gravity' descends from Latin 'gravitas,' meaning heaviness or weight, from 'gravis,' heavy — the same root behind 'grave' and 'grievous.' 'Assist' comes from Latin 'assistere,' to stand by or help. The phrase itself is a 20th-century space-age coinage; the technique was worked out mathematically by mid-century engineers and famously exploited by missions like the Voyager probes, which hopscotched from planet to planet by borrowing each one's pull. Also called a 'slingshot' or 'gravitational slingshot,' a nickname that captures the flung-stone feel of the trick.
- momentum theft
- the planet slows imperceptibly; you speed up enormously
- voyager veteran
- used Jupiter and Saturn to escape the solar system
- fuel savings
- some missions impossible without these free velocity boosts
- reverse gear
- works to slow probes down toward the inner planets
- chained slingshots
- Cassini used Venus, Earth, and Jupiter en route to Saturn
voyager 1 jupiter flyby — 1979 gravity assist that accelerated the spacecraft to escape the solar system
parker solar probe venus — repeated venus gravity assists since 2018 to spiral closer to the sun
cassini saturn arrival — 1997 jupiter gravity assist on route to saturn, reducing fuel needed by months of propulsion