Chapter 9. Rocket Science

Rocket science has a bad reputation: like brain surgery, it has been held up as something too hard for the average Kerbal in the street to understand. In the last chapter, we took a tour of the basics of the game. In this chapter, we’re going to start learning rocket science.

You don’t have to be a rocket scientist to use rocket science, as there are a few simple numbers you can calculate using relatively simple formulas that are going to help you not blow up your rockets quite as much as you would otherwise.

You don’t have to know everything in this chapter in order to have fun playing Kerbal Space Program. That said, KSP attempts to model space flight as realistically as possible and implements rocket science as well as it can. If you understand why rockets, planets, and moons move in the way they do, you’ll find it easier to do more advanced stuff in the game.


The Kerbal Space Program Wiki has a good summary of physics and orbital mechanics terminology that may come in handy.

The Law of Conservation of Momentum

The basic principle that all rockets work by is the law of conservation of momentum. If we have an object with a mass m moving at velocity v, then the momentum of the object will be p:

p equals m nu

However, the law of conservation of momentum states that the total momentum in an isolated system is conserved; it can’t change. That means if the “system” ...

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