 "spacecraft")
Traveling the vast distances of space isn’t cheap. It costs spacecraft time, fuel and money. Fortunately, nature offers free help along the way and mission designers always take it.
They’re called gravity assists.
In these manoeuvres, a spacecraft exchanges its momentum in a close encounter with a planet to gain velocity. Gravity assists have been used in numerous interplanetary missions to propel spacecraft towards their destinations.
Gravity assists are also useful because it’s not practical to simply add more fuel to power a spacecraft. Adding more fuel makes it weigh more. This means more fuel needs to be added to the rocket to
