Spacecraft use "rocket propulsion" to move up and forward. Rockets use the push of burning fuel. They do not use air, like a jet, since space has no air.

A jet airplane uses less fuel than a rocket. The jet engine uses air and fuel to push forward, the rocket must use only fuel. In both a rocket and a jet the push forward is called the "reaction thrust principle".

An easy way to demonstrate this principle is to take a balloon, fill it with air, point the opening down and let go. The air in the balloon will escape "pushing" the balloon in the opposite direction, up!