Hello, I have a question about gravity assist, how is it possible that a planet can accelerate a space probe that is already faster than the planet (around the sun)? or how is it possible that a planet can decelerate a probe that is already going slower than the planet (around the sun)?I have difficulty understanding this.Thanks !
The method involved using the gravitational influence of an easy-to- reach nearby planet to catapult a free-fall space vehicle to a more distant planet—a trip that would ordinarily require substantial rocket propulsion and/or trip time using traditional direct-transfer trajectories. Moreover, Minovitch also recognized that by using a series of such trajectory-changing planetar)' encoun ters, it is theoretically possible for a free-fall vehicle to travel to many planets without any onboard rocket propulsion (beyond that required to reach the firstplanet and to correct for minor trajectory errors).