How to Setup a Synchronous CommNet Relay System Without Any Maths

[IndivisibleByOne]

So, a bit of an introduction:

Like many of us have before, I’ve found the need to put up some satellite networks as I play the game. Exactly when and where tends to vary a bit, but if you’re a bit mad like me and like to play without the extra ground stations, you need them sooner rather than later.

The best way to ensure commnet coverage is to have at least three satellites in orbits that are synchronous, so that their orbits keep them in the same relative position to one another getting no closer or farther apart. This way one of the satellites will always be in contact with Kerbin, and can then relay that signal out to the rest of the network. This doesn’t need to be geostationary, where they stay in the same place relative to the surface of Kerbin as well as each other.

I’ve read a few guides on how to do this, and they all talk about “resonant orbits”, “orbital periods”, and involve *shudders* maths. While all very interesting and accurate, these methods never felt very “Kerbal-y” to me. When I play, I like to just slap things together with a vague notion of what I’m doing and get to space with nothing more than a hope and a prayer… and maybe a few struts…

So, I’ve devised a method to create a stable satellite network without the need to use lengthy calculations. It involves no mods, and can be done in the base game. And I intend to describe it here in detail for everyone else’s enjoyment.

Below is the craft that we will be throwing into orbit:

Or more precisely we will be putting four of these simple satellites in orbit. Why four when we can get all the coverage we need with only three synchronous satellites? I’ll get to that later, but we will need to get the thing in orbit first. So, we need something to deploy it from first. Something like the below:

It’s pretty straight forward, I’ve complicated things somewhat with using the hardpoints and stack de-couplers rather than radial de-couplers, however radial de-couplers will leave something attached to the satellite making it harder to control. Hence my bodge job. Anyway, wrap that thing up in a fairing and strap an ascent stage to it and we can launch this sucker!

One thing to make sure to do before we do though (as well as check yo’ stagin’ ™) is to reduce the ejection force of your de-couplers/separators (which can be done by enabling advanced tweekables in the options menu). Otherwise you will catapult these tiny satellites halfway around the planet.

Next throw it into orbit. I’m not going to explain how to do that, I’m assuming that is straight forward for most people (otherwise there are good guides on this very forum). Select your preferred altitude and try to get a roughly circular orbit. I selected close to 1 million miles, as I like round numbers but am too impatient to get close to them.

Now here comes the clever bit. Decouple one of the satellites, let it drift away from the main craft for a bit and select the main craft as a target. (Don’t forget to deploy the solar panels)

With this done we will now have the closest approach indicators, orange and purple, showing up on the orbit of the little satellite. This is what we are after and is the key to this method of setting up equally spaced satellites. Now make sure the engine of the satellite is activated and point retrograde and fire up that mighty ant engine. Please be sure to allow for enough drift distance, or push away from the carrier craft just a little, otherwise you will rapidly disassemble everything. Anyway, what we are interested in here is the first and second intercept markers. We keep thrusting until the two intercept lines are visually at right angles. This is the only reason that I use four satellites, I find right angles and straight lines easier to judge by eye than 120 degrees. Note, if you build deploy your satellites using radial de-couplers rather than my needlessly complicated setup you will be left with de-coupler remnants on the satellite and it will need a little finagling to fly, but SAS is your friend.

Once that is done, let one full orbit go past and set up a manoeuvre to re-circularise the satellite’s orbit. Or if you are impatient like me you, can de-couple all of the little satellites and let them all fly our together. it saves time but can be a little hectic, so the choice is yours. You need to do one more exactly like before, we will let this one travel around this orbit twice to reach the opposite side of the planet with respect to the carrier. The third satellite will need to be accelerated forward prograde until the markers line up at right angles, so that it will go 90 degrees in the opposite direction from the first two.  The last satellite you will leave alone, it needs to stay in place because we are going to de-orbit the carrier as its job is over now and I detest space junk. You will also want to swap all the non-circular orbit satellites to target this one now that the carrier is gone.

Next when the first satellite we sent off completes one orbit we will re-insert it to a roughly circular orbit. Notice that lovely straight line made up of the purple and orange markers? That’s what we want to see.

Honestly though, it’s a little irrelevant at this point. Now we are roughly in place what we really want to do is get the apoapsis and periapsis values of the target satellite and this satellite to be as close as possible. The closer they are the less drift away from these relative positions there will be over time. You can check this yourself by placing a manoeuvre node and increasing the time to the node by a few orbits, as we can see the orbit remains almost unchanged after 70 days.

If the markers start moving, you will know that you need to do a little bit of tweaking. at either the periaps or apoaps to fine tune them. You may need to tweak the thrust limiter to get fine enough control.

The markers may not give a straight line, for the satellite pictured below I had to line up the top purple icon with the bottom orange one. You will also notice that my periaps is off by about 6km, so I had to fix this when this satellite eventually makes its way to apoaps, I could also trim the apoaps if I was a perfectionist, which I am not.

Once this has been done with all three satellites and you have trimmed the orbits as much as you desire (less fiddling now means more fiddling to restore the orbits in the future)

 

Hey Presto instant satellite network, no maths, no mods.

 

I hope everyone finds this useful.