If you are interested in gaining a more intuitive understanding of the forces in play (and have some time to kill), I recommend grabbing a copy of Kerbal Space

If you are interested in gaining a more intuitive understanding of the forces in play (and have some time to kill), I recommend grabbing a copy of Kerbal Space Program. Its only in alpha right now, but its a heck of a lot of fun already and does a really good job of teaching you how to use orbital mechanics to land on other planets (or to shoot a probe out of the solar system, if you want to try to do that). Their model is definitely simplified (no lagrange points, for example), but the major aspects are modeled well enough to give you an idea of how interplanetary space travel works. http://kerbalspaceprogram.com/ http://kerbalspaceprogram.com/