Question about what I think is a Geostationary Orbit

[G'th]

So with the Mun fiasco I had earlier, I resolved to finally set up my satellite networks for the Kerbin system, and my first task was to place one in a Geostationary orbit above KSC. The orbit I have right now is 2.868Mm by 2.864Mm.

Obviously eventually I'll lose connection with KSC with this sattelite, but is this good enough for this purpose, or will it deviate too quickly, relatively speaking? As in, how long can I expect the connection to remain with KSC?

[Snark]

Orbital period varies with the 1.5-power of the average radius (e.g., 4x radius = 8x period).

Your average radius is 3.466Mm (allowing for Kerbin's 600km radius), or about .9994 of the keosynchronous ideal. Raise that to the 1.5 power, we get .999135. Take the reciprocal of that, subtract 1, then reciprocal again, and we get an orbital period of 1155 days relative to the surface.

So if you're starting directly over KSC, you should have a few hundred Kerbin days before losing LOS.

[FancyMouse]

I don't put geostationary satellite at all. I just arbitrary pick one (depending on antenna I have, etc.) and shoot one rocket that carries all satellites on this orbit, and place them in one launch. First batch will be manned, of course, but that doesn't matter. You have full freedom of choosing which orbit you want to put. On the other hand if you just launch one satellite at a time, you'll need a careful plan of the second launch and often you can't just pick arbitrary orbit you want for the first one.

[MarvinKitFox]

There is a simple way to know when you are in a true geostationary orbit (as opposed to a mere geosynchronous orbit,)

If your ground speed is zero and stays zero, you are there.

This rather requires you to be directly above the equator, and at an altitude of 3468km. Correction, 2868km above surface.

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However, from your concern about communications line-of-sight, I believe that what you are looking for is not a geostationary orbit, but a geosynchronous one.

The only requirement for this is that you orbit in the right direction, and have an orbital period of *exactly* one day kerbal time.

Your ground track may wobble around in interesting ellipses or even figure-eights, but if your period matches Kerbin's rotation, you will not drift off to the east or west.

Edited June 5, 2015 by MarvinKitFox

[Geschosskopf]

What works for me is not to worry so much about being totally geostationary. If your satellite wobbles a little bit around a fixed spot in Kerbin's sky, that's good enough because you'll still never lose touch with the tracking station. It's like how Ike wanders around a small patch of Duna's sky but never leaves that area. So at the bottom line, all that matters is orbital period, which is what keeps your satellite from drifting below KSC's horizon over time. Put your satellite as close to KSC's zenith as you can, at approximately the right altitude and approximately 0 inclination, but don't sweat it if you don't get any of that exactly right. Then open some window that will show your orbital period and use RCS to tweak that until it's exactly 6 hours. That's it.

[Superfluous J]

Note that without something like HyperEdit (Or editing the save file directly) nothing will keep your satellites from wandering eventually. It's impossible to get the orbits exact. They may be good for years, but not forever.

I vaguely recall a mod out there that would do it. I think IIRC that if you got a satellite within 1% of the orbit you wanted, it would allow you to snap it to that orbit to keep it there forever.

[Orbital Vagabond]

Is Kerbin's sidereal period still 6 hours? I thought they changed the synodic period to 6 hrs back in 0.24 or something.

[Superfluous J]

It was 6 hours in .25, which is the last time I used RemoteTech and made a constellation of Keostationary satellites.

[GoSlash27]

So with the Mun fiasco I had earlier' date=' I resolved to finally set up my satellite networks for the Kerbin system, and my first task was to place one in a Geostationary orbit above KSC. The orbit I have right now is 2.868Mm by 2.864Mm.

Obviously eventually I'll lose connection with KSC with this sattelite, but is this good enough for this purpose, or will it deviate too quickly, relatively speaking? As in, how long can I expect the connection to remain with KSC?[/quote']

According to my math you'll lose 25.43 seconds a day. That's good for 189 days.

Bump up your periapsis to 2.869 and you'll lose 2.9 seconds per day have LoS for a lot longer than it'll ever matter.

And it's not like you can't make minor correction burns to keep it on station.

Good luck!

-Slashy

Edited June 5, 2015 by GoSlash27