Orbital period not as stable as expected

[Cairol]

A short question: Yesterday I set up a satellite network around Mun.

And while fine tuning the orbital period of the sats I noticed that the period was fluctuating by several seconds while the satellite was orbiting the Mun.

From my understanding, the orbital period should be perfectly stable down to some milliseconds if the satellite does not accelerate or rotate by active control inputs.

(RCS off, Engine off, SAS stability mode enabled)

My orbital network around Kerbin has super-stable orbital periods for all satellites. I was able to fine tune them down to a couple of milliseconds. The jitter of the shown values is miniscule.

But around Mun, it's not that stable.

My fear is, that those satellites will de-synch while on fast time acceleration during longer interplanetary transfers, because the deviation is in the seconds area.

Why is that?

Edited September 18, 2015 by Cairol

[Xeiki]

I can't tell you why, I can only say that in my experience, the farther away you are from Kerbin, the less accurate the Orbits and Nodes become. That may be just an illusion - but your satellites should be fine under time Warp, as orbits appear to be fixed then. But it can happen that you enter timewarp at a large fluctuation wich changes the orbit permanently.

[RidingTheFlow]

I can't tell you why, I can only say that in my experience, the farther away you are from Kerbin, the less accurate the Orbits and Nodes become. That may be just an illusion

It's not an illusion. They become less accurate and more "twitchy" because orbital velocity decreases to the point when even miniscule changes to ship velocity cause visible orbit changes. And when you are not on rails (timewarp), ship never has constant speed - it always fluctuates ever slightly, because physics engine is not 100% accurate.

Same thing applies to low-velocity orbits around bodies with low gravity.

[Cairol]

I thought Swat fixed this "increasing inaccuracy for outer regions" by dividing the space into several patches with their own center for calculations to reduce floating point errors?

So I basicly have to live with this and hope the satellites will not de-synch in the forseeable future...

[xtoro]

This is where I go into my persistent file to make changes for my RemoteTech network around Kerbin. I get them as close as I can to geosynchronous orbits, exit the game and open up my persistent file. Find both crafts, and under the orbit{ section, I make sure the SMA=##### are identical. Then they stay in sync as long as I dont move them.

Some may call it cheaty, but it's your game, do what you want. In my roleplay aspect of it, the satellites are just doing their own automatic adjustments to stay in position...

Edited September 18, 2015 by xtoro

[0111narwhalz]

It would seem your best bet is to never look at your satellites again. When they're unloaded, their orbits won't change because their velocity doesn't. You should be fine as long as you never load them back up.