[RemoteTech] Comm Relay -- Getting Angle of Seperation right?

[Peppe]

I successfully deployed a warp stable network -- it may eventually need a tuning, but the orbital periods are synced by the semi major axis down to the meter (using VOID - clicking on the major access changes the units).

My plan worked, but would like to understand why it worked. Also if i wanted to make it a 4 sattelite network how i would move the existing satellites around to equally space the new amount.

Should the argument of periapsis be 120 degrees apart or is that only if they are all circularized perfectly?

What data can i use other than lost signal to identify if I need to move any of the satellites?

or

If i had launched each satellite separately what would be the best/easiest way to ensure they were 120 degrees apart?

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My mission plan to deploy a remotetech comm relay network.

3 Satellites with 5000 km omni antenna.

120 degrees apart to form a triangle around the equator and maintain 100% comm with KSC.

Satellites in circular orbit @700km.

Deploy on one craft initial deploy orbit 700km 70km. This is 2/3 of the final orbital period. Each apoapsis I released a relay and circularized it. Circularize burn got a little tricky. First two i ended up doing with my deployment craft and then the third had to do it's own burn.

Edited January 2, 2014 by Peppe

[DeMatt]

I successfully deployed a warp stable network -- it may eventually need a tuning, but the orbital periods are synced by the semi major axis down to the meter (using VOID - clicking on the major access changes the units).

My plan worked, but would like to understand why it worked.

Hrm... I'm not entirely sure what to tell you, other than to point out that synchronizing the orbital periods (or the semi-major axes) is exactly how to get satellites into a stable configuration.

Also if i wanted to make it a 4 sattelite network how i would move the existing satellites around to equally space the new amount.

Adding a fourth satellite to an existing three-satellite constellation would require you to 1) pick one satellite as your reference, 2) move the two other existing satellites into (probably) the +90 and -90 degree positions (from their current +120 and -120 degree positions), and 3) launch the fourth satellite into the +180 degree position.

Should the argument of periapsis be 120 degrees apart or is that only if they are all circularized perfectly?

The traditional way of setting up a global communications relay is to put three satellites, spaced by 120 degrees, into the same orbit. That is, all their orbital elements are identical save for the "mean anomaly at epoch", placing one satellite "ahead" or "behind" the other two by the aforementioned 120 degrees. The "argument of periapsis", in such a case, should be identical for all the satellites, as they are all tracing out the same orbit - just at different epochs along said orbit.

What data can i use other than lost signal to identify if I need to move any of the satellites?

Since "carriage of signal" is the only reason for those satellites to be where they are, I would suggest that "loss of signal" is indeed the only data you need to decide whether to move a satellite or not.

If i had launched each satellite separately what would be the best/easiest way to ensure they were 120 degrees apart?

Launching them 1/3 of an orbital period apart, and doing your best to follow the exact same launch trajectory each time, would probably be your best bet.

[Peppe]

Thanks. Think that confirms I did things about as well as you can by hand.

In the last few minutes I have found the rendezvous information screen on VOID useful.

I could set both a target and have another vessel selected from the register. This allowed me to see my distance to both other satellites at the same time. Pretty easy to fix a triangle using that information

Since my orbits aren't perfectly circular I just picked a satellite and adjusted so the distance to each other satellite was equal. Watched a few orbits and as they speed up/slow down in Ap/Pe they moved a little, but I think i averaged their distance well. Did the same for a second satellite (affected the first one a little, but mainly dialed in its distance to the final satellite).

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I also found in this situation the actual angel of separation is local sidereal longitude. If I bounce to each satellite quickly enough their sidereal longitude values are now all ~120 degrees from each other. Before i adjusted they were 124, 118, 118 -- seeing these confirmed what i felt that my triangle was a bit off

I think if my orbit was KEO the sidreal logitude would not change and that would be an easy reference point to place satellites along.

Looking at adding a satellite to an existing set I used a spreadsheet i have been working on. It calculates the distance to the neighbor satellite. With that as a guide i would launch the 4th satellite roughly in a spot it will eventually go. Use one existing satellite as an anchor and move the other two to the proper average distance, then nudge the 4th around so it too is equidistant. Then use longitude to confirm their degree of separation is right -- hard to use that to do the actual maneuvers since it is a moving target.

Maybe you could use the rotation of the planet to predict what your longitude should be at a certain point? seems more complex than figuring out what your distance should be and extending/shorting your orbit as needed for a lap or two to line things up..

Spreadsheet mentioned above:

http://forum.kerbalspaceprogram.com/threads/52132-Spreadsheet-to-Calculate-Orbit-Orbit-Darkness-and-Recommended-Battery-Capacity