How Do Planetary Flybys ActuallyWork?

The Voyager spacecraft famously flew by the giants in the 1970s and 1980s. NASA.

Gravity assists, sometimes called flybys, are a big part of space exploration. These precision maneuvers involve harnessing a planet’s gravity to accelerate and direct a spacecraft to some far-flung destination so the spacecraft can go further without a big and heavy propulsion system. It’s a key element in both human and robotic space explotration.

What is a Flyby?