It wasn't long ago I was asking this very question. There are some awesome people here who helped, so hopefully I wont steer you wrong. What I do is take all four probes with me. I move to the geosynchronous orbit and circulize it. I then look at how long it takes to make a complete orbit (I use Engineer Redux but there are other ways). I divide that value by 4 (or however many probes you are launching) and then burn pro-grade until my new orbit is exactly that amount above the orbit time. Sorry, I think I'm getting confusing. As an example, if the orbit time is 4 hours, I would burn a new orbit that takes 5 hours; if the original is 6 hours, I would burn a new orbit that takes 7.5 hours, and so on. (Don't circulize this orbit, it will end up sort of egg shaped with the periapsis lying along the orbit you want) Then, I release a probe just before what ends up being the periapsis and have the probe circulize it's orbit which brings it's orbit time back down to the original amount (4 or 5 hours in this example). Then as my main ship moves through its longer orbit, I release another probe when it returns to the periapsis and follow the same steps. When done, I end up with four probes each spaced 1/4 of the whole orbit from one another. EDIT: This will work for any circular orbit. In case you don't already know, the Kerbal Wiki will give you the distance needed to orbit in a geosynchronous manner for each of the planets.