In this chapter, you’ll learn how to design and fly vessels that travel beyond the orbit of Kerbin. You’ll learn how to get your craft to every Kerbal’s favorite tourist destination, Mun, and how to build craft that can travel to and land on the distant planets beyond.
There are three very important maneuvers that you need to get around in space: launching, landing, and transferring between two different orbits. We’ve talked about launching and landing quite a lot in this book, and it’s time to start talking about orbital transfers in more detail, since it’s a vital piece of knowledge if you want to travel to other planets.
An orbital transfer is a maneuver in which you change which planetary body you’re orbiting around. If you’ve traveled from Kerbin to Mun, then you’ve already done a simple orbital transfer: you’ve transferred from Kerbin’s orbit to Mun’s orbit, by raising the apoapsis of your orbit to match Mun’s orbit, and timing this burn so that the new apoapsis happens to be within Mun’s sphere of influence. From there, you can then perform another maneuver to circularize your orbit around Mun.
Because Mun is orbiting Kerbin, this particular orbital transfer is relatively simple. Mun’s orbit is almost circular, which means that the distance between Mun and Kerbin is roughly the same at all times. The orbit of Kerbin’s other moon, Minmus, is slightly more complex, because the orbit is slightly more ...