Kerbal Space Program (KSP) is a computer game in which the player can build rockets (and spaceplanes, rovers, etc.) from a large set of predefined parts and then pilot them in a simulated solar system. In the simulation, every vessel in space travels according to Kepler's laws (i.e., the vessel's path follows a conic section, as though it feels gravity from only one planetary body). This simplification has been the topic of many conversations in the game's forums and I thought it would be interesting to explore whether and how more accurate trajectories for vessels could be computed using Newton's laws. I believe that using Newtonian trajectories in KSP is possible, although whether there is a compelling gameplay reason to make the change is a different question.