Once a satalite is in orbit, it takes very little energy comparitively to maintain said orbit. as the satalite approaches the highest point in its orbit, it turns prograde and fires thrusters to raise the lowest orbital point to the same elevation as the highest orbital point, which is usually a rather small adjustment. The hard part energy wise is getting the satalite into orbit in the first place.
The whole reason for earth launches having two stages, one vertical, one horizontal(orbital) is due to our relatively thick atmosphere. A launch on the Moon say, would be much more effecient at an angle to give it high initial Horizontal (orbital) speed.
Not sure how much any of this would have an effect on the game... it's too early... where's my cofee? *wanders off in search of cofee*
