I have been trying to work out how much ΔV would be required to deorbit a spacecraft after it had achieved escape velocity from the moon but I don't know how to work out what the radius of the orbit would be after it had escaped the moons gravity.
Say you were in a lunar orbit at 100km, and you made you burn at your lowest altitude (relative to earth) e.g. moons orbit minus 100km, when you got out of the moons gravity well and into the earths, how big would your orbit around the earth be?
Would I just have to rearrange the vis-viva equation to calculate my radius with the speed that I had after the burn?
I know thats not very well put but I hope you understand.