The Physics of Space Battles - Space battle - Gizmodo
http://gizmodo.com/5426453/the-physics-of-space-battles

"Another is that combat in orbit would be very different from combat in "deep space," which is what you probably think of as how space combat should be – where a spacecraft thrusts one way, and then keeps going that way forever. No, around a planet, the tactical advantage in a battle would be determined by orbit dynamics: which ship is in a lower (and faster) orbit than which; who has a circular orbit and who has gone for an ellipse; relative rendezvous trajectories that look like winding spirals rather than straight lines."

First, let me point out something that Ender's Game got right and something it got wrong. What it got right is the essentially three-dimensional nature of space combat, and how that would be fundamentally different from land, sea, and air combat. In principle, yes, your enemy could come at you from any direction at all. In practice, though, the Buggers are going to do no such thing. At least, not until someone invents an FTL drive, and we can actually pop our battle fleets into existence anywhere near our enemies. The marauding space fleets are going to be governed by orbit dynamics – not just of their own ships in orbit around planets and suns, but those planets' orbits. For the same reason that we have Space Shuttle launch delays, we'll be able to tell exactly what trajectories our enemies could take between planets: the launch window.

The Physics of Space Battles

I hope someone's working on the simulation.