Welcome to the KSP Un-Orbit Calculator written by SharpCoder (@ecmahacker). This calculator is designed to tell you roughly when to burn retrograde during a landing. I am not a mathematics guy, so this works more like a simulator. Think Monte Carlo Method! In an effort to make it really easy to use (and in traditional kerbal fashion) I've made a lot of assumptions about your ship and its orbit. USE AT YOUR OWN RISK!