How Do Planetary Flybys ActuallyWork?
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?
A flyby, also called a gravity assist, is a manoeuver that allow a spacecraft to gain velocity or delta-V from passing by a planet, and in some instances, use that planet’s gravity to bend its trajectory to change direction. No matter the specific flyby’s outcome, it negates the spacecraft’s need to carry a big engine to make a trajectory-modifying burn. This is different than a flyby mission; a flyby mission is one that sees the spacecraft photograph and measure its target without stopping in orbit.
We can look at the New Horizons mission to Pluto to understand one of the basic issues affecting all spaceflights. When the spacecraft did its close encounter with Pluto, a lot of people asked why it wasn’t going into orbit. It was, in effect, going too fast to stop. The crude but apt explanation: it was launched on an Atlas rocket, so it would need the same thrust in reverse to slow enough to stop at Pluto since the small planet’s gravity wasn’t enough to…
