Placing my communication satelites

[wildwinds]

Say I have a comm sat in geostationary orbit around Kerbin, how do I launch another one into the same orbit but 180 degrees away from the first one. Also what is the proper terminology for what I am try to accomplish?

Thanks in advance!

[Jupiter3927]

Launch it exactly like you did for the first one.
Set the first relay as your target and play with manuevers until your closest approach is about 180 degrees away from your target.
Perform the manuever and circularize and you're done.

Most relay systems need at least 3 satellites.
Your 2 satellite system will never have both relays connected directly.

[andylaugel]

The way I've done this sort of thing is to put my craft in an eccentric orbit whose Ap is at the geosync altitude. At the Ap, I can burn to adjust my orbit's period to be whatever fraction of the geosync's period to get where I need to go. In a pinch, you can be a little random and just wait until the orbit that lands you where you want to be.

When I've done this, it's been with a single multipayload craft. For a perfect triange, I'm aiming for a 2/3 geosync period--although 5/6 can work if I'm willing to wait two orbits between each launch. At the Ap, I'll detach a single satellite and have it circularize its orbit.

[wildwinds]

I know I need more than 2 sats, I figured if I could launch 2 sats 180 degrees apart, then I could do it again with 2 more sats and have 4 total. I tend to use MechJeb 2 for a lot of my maneuver planning, is there anything in their that could make things a bit more precise?

[Jupiter3927]

Do all your tiny manuevers manually with an Ant engine at 0.5% thrust.
Autopilot sometimes has a hard time with precision.

Getting your orbit exactly perfect is impossible.
Altitude is measured down to at least millimeters but is displayed in meters.

[desrtfox071]

One option to do this (not quite what the OP is asking) is to launch a rocket with all of the communications sats onboard (say 3 of them). Put that rocket in an eccentric orbit such that the Apoapsis is the altitude that you'd like to deply your sats too. Then, make sure your Periapsis is such that you evenly divide the projected oebital duration by the number of sats.

So, to make things more clear. Say you're launching 3, get your rocket build, and get it into an orbit with an Apoapsis at the right elevation (let's call it 800km), now make your orbital period something liek 2/3rds (or 1/3rd) of the orbital period of the circular orbit at that altitude (look that up or calculate it). Now, each time your rocket reache the Apoapsis, it will be 1/3rd of the orbit off from the previous time. Each time the rocket reaches Apoapsis, launch one sat from it, and circularize the orbit with that sat (it must have it's own engine obviously). In this way, you can easily deploy a whole constellation of comm sats and keep them pretty evenly spaced out.


Now, given that the OP already has one sat in orbit, the thing to do would be to launch the new sat into the elliptical mentioned above, and compare the position of your new rocket, with sat on bard, with the existing sat already in orbit. When you are at apoapsis with the new sat, and your farther than about 1/3 of the orbit back, deploy the new sat. Do this a couple of times ans you should be good.


If you don't like precision, or don't want to take the time, you can always just launch a bunch of comm sats to the same circular orbit. So long as you launch them at different times, you'll get enough coverage to do the job. That's not as efficient, or elegant though :)

[Mor'finn]

If you want to be precise and without any guesswork, you can just calculate distance between satellites in your constellation. It is just simple geometry, s=2*sin(pi/n)*(r+a), where s is separation between satellites, n is number of satellites in constellation, r is planet's radius and a is constellations altitude.

For two, three and four satellite constellation, formula simplifies nicely to s=2*(r+a), s=sqrt(3)*(r+a) and s=sqrt(2)*(r+a).
For two satellite constellation at keosynchronous orbit separation is s=2*(600 km+2863.33 km)=6926.66 km.

To get the satellite into constellation, launch to 80 km parking orbit. Then match planes with the target satellite. Next make maneuver node to raise the apoapsis to constellation altitude and adjust burn timing so that the separation at the intersect is calculated separation. After executing the maneuver just circularize at the constellation altitude and match orbital period with the target satellite.

https://steamcommunity.com/sharedfiles/filedetails/?id=1619220395

[RoofCat]

it's all nice and accurate for satellite launch spacing in general case. Like solar orbits.

But doing that for geostationary Kerbin it's not really needed. LKO is just ~30 minutes. So decoupling and propelling prograde another satellite every 10 (..11) min will pretty much send them in an almost perfect 120°-120°-120° distance.
Geostationary orbit is exactly one day long. Just not the solar day of exactly 6h. One full Kerbin rotation is slightly shorter than that. Kerbin moving on a circular orbit while also rotating makes sunlight (day) cycles slightly longer than one full rotation (which is about the geostationary stuff).
So keeping that in mind you can actually make perfect spacing taking into account proportion of how much 10min delay on GEO orbit is when projected on LKO (10min vs. 359:xx min)

So in case your full (as circular as possible) LKO takes exactly 30 minutes, your next launch should be not just 10min, but rather 10min+1/36 from 10min. Something like that. Because the first satellite has already moved (a bit) while the second one is launched after a delay.

But really that level of spacing accuracy might be overkill as the accurate GEO altitude and perfect circularity is much more important long term than perfect spacing. As even few minute orbital length differences will get some of them close within months thus ruining even the best spacing.

And then GEO satellites for Kerbin are almost useless (except you keep just one ground station). The range is much too short to profit from these relays in a global case. They don't even help with Mun. All craft will connect to ground stations directly anyway. Just a waste and debris spam in space. As for surface operations with small antennas in hard to reach spots - well why would you do those in the first place on Kerbin in a space sim. And then GEO might be too far already for those tiny, snail slow rover antennas hiding behind a hill from nearest surface anteanna. Planes are high enough for most part and fly manned!



I'm not saying it is all bad and you should never ever do GEO satellites around Kerbin. But in 99% cases it pretty much is complete waste and bs. Splitting molecular nuts for dead squirells.

[Toastie Buns]

You only ever need 1 GEO sat, it's a range extension for your tracking station (Gives it the ability to look past the only issues it has; KSC's mountain range and the horizon)
Another two lofted into an inclined polar orbit gives you the ability to look over/under everything, far more valuable than satellites stuck in the same orbit as the Mun. If you super size the ♥♥♥♥ out of them, they're fully upgraded Eeloo capable DSNs, you won't even need T3 tracking stations.
Keep that periapsis low and apoapsis as high as you desire (keep in mind you want antenna-less craft to connect so too high is silly) and you'll find you've got damn near 99% connectivity.