# How precise must a satellite's orbit be?

I was thinking about the question on solid upper-stages and my feeling that a liquid upper-stage would allow a more precise orbit. But... how precise does an orbit actually have to be? I guess I mean the initial placement, and we can assume the satellite can make small corrections if needed. But there are also a lot of satellites without engines, like most cubesats, and they just tumble around wherever the dispenser throws them along the orbit of the primary payload, and it could be days before the operator is even given the official orbit parameters. So there has to be a certain amount of "slop" that can be tolerated, I would think.

• Perhaps a more useful question would be, "Which satellite applications require the most precise orbit?" – DrSheldon Jun 9 '19 at 1:20

This largely depends on purpose/application, but if you want it just to "be in orbit" then the answer is "not very precise at all.". Or quantifying better, the periapsis speed must be between the speed of circular orbit and escape speed which is $$\sqrt{2}$$ of that - so about 40% of "slop".