Jump to content

How do you make a proper constellation of geostationary sattelites?


Recommended Posts

Hello all,

i've been thinking of messing around with remotetech or antennarange or something similar, and i'd like to know how you can set up a proper geostationary constellation. By proper, I basically mean evenly spaced out sattelites on the same orbital height.

So what's the trick to doing this? if I have say 4 sattelites and I would like to deploy them in such a manner that I'll have them form a square on geostationary orbit, how do I do that?

In essence I guess I'd just have to get to orbit, release sattelite, burn prograde with mothership and make sure that the orbit of the mothership takes 1/4 times longer than the orbit of the deployed sattelite. But how can I calculate this or even get the data I need to calculate it?

thanks in advance

God I always feel like such a noob when asking this sort of stuff. I'm an engineer, I should bloody well know these things...

Edited by Cirocco
answered :)
Link to comment
Share on other sites

T=2À√(a³/μ)

T is Orbital period, a is semi-major axis and mu is standard gravitational parameter (you can find for each planet on the wiki). forum font does not display pi very well,

Edited by Rhomphaia
Link to comment
Share on other sites

So, here is my kerbal way of doing it (note- this is for dumb satellite without any kind of proplusions):

  1. Go to desired orbit - release first satellite
  2. Select the satellite as target
  3. Make a maneuver node at periapsis
  4. Add prograde movement to the node until you see your closest approach/target location is seperated by 90 degrees (get a protractor and place it on kerbin's pole)
  5. Execute it.
  6. Retro burn as you approach the periapsis again until your apoapsis get to the same height before. You are now behind your satellite by 90 degrees on the same orbit.
  7. Release second satellite.
  8. Select second satellite as target
  9. Repeat 3-6 with the second satellite.
  10. Do the same for subsequence satellite - remember to select the one you last release.

Edited by RainDreamer
Link to comment
Share on other sites

Or:

1. Make a mothership with 4 satellites.

2. Make your orbit with a period od 4:30 hours with AP at 2868,75 km.

3. Each orbit on Ap release 1 sat and cirlculaze it (make its orbit 6 hour long)

4. In 4 orbits of the mothership you shold have 4 evenly spaced comm sats.

Link to comment
Share on other sites

Or:

1. Make a mothership with 4 satellites.

2. Make your orbit with a period od 4:30 hours with AP at 2868,75 km.

3. Each orbit on Ap release 1 sat and cirlculaze it (make its orbit 6 hour long)

4. In 4 orbits of the mothership you shold have 4 evenly spaced comm sats.

That's the easiest way to do it, if your satellites are small enough that you can put 4 on a mothership.

Link to comment
Share on other sites

That's the easiest way to do it, if your satellites are small enough that you can put 4 on a mothership.

That was the idea, yes. They'd just be small comm sattelites.

Okay, got a lot of good info, thanks guys. I should be able to get a good constellation with this. Now I just need to figure out the easiest/quickest way to find/calculate the orbital period of my orbits.

Link to comment
Share on other sites

That was the idea, yes. They'd just be small comm sattelites.

Okay, got a lot of good info, thanks guys. I should be able to get a good constellation with this. Now I just need to figure out the easiest/quickest way to find/calculate the orbital period of my orbits.

Kerbal Engineer Redux has such readouts, you should try that. I think mechjeb has it too. If you don't want any mod, try this online calculator thing: https://dl.dropboxusercontent.com/u/1646976/KSP%20Calc2/index.html

Serveral more calculator on the wiki list: http://wiki.kerbalspaceprogram.com/wiki/Calculation_tools

Link to comment
Share on other sites

Launch first sat to an orbit of 3,000Km. It should stay in contact with KSP through the whole ascent. This is comms prime.

Wait until it is above KSC then drop your orbit to around 2.8Mm with an orbital period of EXACTLY 6 hours.

Make sure it has the 5Mm omni antenna at a minimum. Try to get your orbit as circular as possible.

Now you can launch two other comms sats to orbits of about 2.5Mm and 3Mm and then put them into 6 hour orbits when they are nearly on the other side of the planet but still with line of sight to comms prime (to make an equilateral triangle)

Now launch a directional (many dishes) comms sat to near comms prime also with a 6 hour orbit.

At this point you can launch your first Polar interplanetary comms sat (orbit about 5Mm one equatorial, one Polar) and link them to your multi dish sat

Now you have system wide comms.

EDIT : As you run mods already I suggest either VOID, KER or Mechjeb so you know when you have a 6 hour orbit.

Link to comment
Share on other sites

Or:

1. Make a mothership with 4 satellites.

2. Make your orbit with a period od 4:30 hours with AP at 2868,75 km.

3. Each orbit on Ap release 1 sat and cirlculaze it (make its orbit 6 hour long)

4. In 4 orbits of the mothership you shold have 4 evenly spaced comm sats.

I'll have to remember this. Did a constellation myself just yesterday and it never occurred to me to lift the mothership up to geosynch orbit - I released them one at a time from a mothership in low orbit. Six in my case, and I definitely did not end up with a right hexagon.

For step 2, what should the orbital period be if I did want to build another six-satellite constellation in the future?

Link to comment
Share on other sites

If you want to put up a 6 satellites constellation, each satellite must be 1 hour apart from the next one. To archive that set the orbital period in step 2 to 5 hours.

The calculation goes

pcarrier = pgeostationary - (pgeostationary/ nsatellites)

pcarrier - orbital period of satellite carrier, apoapsis must be at geostationary height

pgeostationary - orbital period of the geostationary orbit

nsatellites - number of satellites for the constellation

Worked great for my 4 sat network

YfBucOQ.jpg

My carrier had to switch between a 4.5h geosynchonous and the 6h geostationary orbit for each satellite because the satellites only have a small amount of RCS to fine tune the orbit.

Edited by *Aqua*
Link to comment
Share on other sites

I think putting up these constellations is cool... but is there any benefit as far as KSP is concerned with having such satellites with COMs on them? Does it enhance communications or something, or is it just a personal challenge? I've not seen anything in the documentation about that (yet).

Link to comment
Share on other sites

I think putting up these constellations is cool... but is there any benefit as far as KSP is concerned with having such satellites with COMs on them? Does it enhance communications or something, or is it just a personal challenge? I've not seen anything in the documentation about that (yet).

stock KSP no there is no benefit aside from personal challenge. If you play with the remote tech mod however you need to maintain a communications network if you want to use probes or transmit science. Each antina has range limitations and needs line of site to either KSC or a satellite able to relay the signal.

Link to comment
Share on other sites

Or:

1. Make a mothership with 4 satellites.

2. Make your orbit with a period od 4:30 hours with AP at 2868,75 km.

3. Each orbit on Ap release 1 sat and cirlculaze it (make its orbit 6 hour long)

4. In 4 orbits of the mothership you shold have 4 evenly spaced comm sats.

I did this for my comm network. Great compromise between simple to execute (but still took skill and care) and accurate. Which to me is "The Kerbal Way"

If you want one without too much work, use HyperEdit

And after I did the above, I then did this. If you put the work in getting them up there, you can consider HyperEdit the equivalent of having a flunky keep an eye on the satellites' orbits and make little adjustments when needed.

I'll have to remember this. Did a constellation myself just yesterday and it never occurred to me to lift the mothership up to geosynch orbit - I released them one at a time from a mothership in low orbit. Six in my case, and I definitely did not end up with a right hexagon.

For step 2, what should the orbital period be if I did want to build another six-satellite constellation in the future?

Any of 1 hour, 5 hours, or 7 hours would work. I doubt 1 hour would have a periapsis over the atmosphere so I'd personally go for 5.

Link to comment
Share on other sites

I honestly eyeballed it :P

Launched first commsat, put it into geostationary orbit.

Launched next commsat, put it into roughly the right direction (roughly a quarter behind or ahead). Used a sheet of paper held against my monitor with the corner pointing at Kerbin's pole, so I could use the sides as a measurement tool to get a 90 degree angle. Lined one side up with your existing commsat, figured out if the new one was slightly ahead or slightly behind, then lowered (or raised) its orbit every so slightly. A few minutes difference in orbital period is fine. Then I timewarp a bit until it is positioned precisely enough for my tastes. Then adjust orbital period to 06:00:00.

Rinse and repeat with the remaining two.

Result: who needs math anyway? :P

Link to comment
Share on other sites

My low-orbit mesh (@ 700km altitude) plus the two at KEO (around 2869km altitude) ends up looking like:

KSP%2B2014-12-06%2B11-52-40-60.png

The KEO sats are just ahead/behind of KSC. They have (1) directional antenna pointed at KSC and the second one is pointed at "active vessel".

Note: I only have 3 of 4 up in the 700km orbit, sat #4 was a failure (ran out of fuel) before getting into position.

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...