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Your relays outside Kerbin's SOI


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Hello guys! It's very common for people to set relays orbiting Mun and Minmus, but have you set any relays at other planets' orbits or any of their moons (or even Kerbol)? Or you really don't need'em?

This is my Joolian relay, helped me a lot in many missions to Jool's moons and in my Eeloo mission.


LY132uQ.png

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I usually try to send an array of relays (3 or 4) before I send manned missions, and attempt to arrange them for proper coverage.  Since I do manned missions far more frequently, the relays are usually just for making sure I can get my science to KSC.

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Frankly, in my recent-ish trip to Duna (and I'd use the same technique for other planets) I sent a set of three relays for equatorial coverage, along with several other manned ships. However, when doing a mission all in one transfer window, I like to plot the transfers so that the relays arrive first. That way they're in the vicinity and at least not on an escape trajectory by the time the manned vessels enter the SOI. I tend to slightly overkill the dV on board the relays' transfer stage so that they can take a faster less 'efficient' path to the body. Depending on how long til your manned craft arrive, you may even have enough time to set the separation orbits for the relays too. :)

Edited by drewthedrewman
Apostrophes dear, apostrophes!
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Since the comm network was included in the game, I changed my way to approach missions and relays quite a bit. I used to put a million relays everywhere and it bugged me to have to launch so many.

Right now, I mostly fly manned within Kerbin's SOI. I find that the low dV requirements of Kerbin's SOI flights don't justify rushing a network to use probes and such. Instead, I wait for RA-2s, set four of them up between the orbit of Minmus and the edge of Kerbin's SOI so that I only really need one launch to get almost uninterrupted 100% signal at equator anywhere around Kerbin/Mun/Minmus.

Then I launch an interplanetary relay, either a ton of RA-15s(to be upgrade later) or RA-100s, and set it up so it trails Kerbin outside of its SOI. That relay then gets uninterrupted signal using the RA-2 satellites and allows me to send pretty much uninterrupted signal to other interplanetary relays even with extra ground stations off. So, in total, that only requires two launches so far.

After that, when I choose to send probes anywhere, I just need to recycle the previous relays and set them up in a similar fashion around my target celestial body. Like @drewthedrewman, I try to get them there earlier using a less efficient but faster transfer.

I also don't really bother with putting satellites around everything elsewhere either. With 4 satellites on extremely high orbit and a 5th sitting just outside your target's SOI, getting eclipsed is rather rare.

I don't really have such an elegant and minimalist solution to getting signal to the poles, though.

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I so far have only played sandbox, and because of that, anything that will stay in orbit has relay capabilities. My main probes, my unfinished space station, and my dedicated relay satellites have 2 RA-100 relays, and my SSTO and first shuttle's external fuel tank have high gain antennas to supplement my relay system. The external fuel tank is from my first space shuttle clone, where I decided to include a mammoth engine on the bottom of the tank to simplify engineering. It also has RCS and a docking port, and is cabable of interplanetary travel, though it would require a slingshot off the Mun to make it to Duna without using RCS fuel for more delta v. I found this out when I decoupled from it with max throttle and it ended up in orbit of kerbol, out of LF+O:D

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I recently did a mission to Duna, but it was manned, didn't need KerbNet for anything, so I didn't bother.  However, I would like to start hunting anomalies and checking out ore locations with probes. (Having life support needs is certainly an incentive for probes.)  I'm curios about how I should go about getting good coverage (and get around Ike, dang it) without using a huge number of probes... for garbage stutter reasons.  I have Memgraph but, while I don't usually have high FPS standards and my PC handles KSP fine, the stutter scares me when attempting suicide burns...

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Well, of course one needs relays for communication with the far side of these bodies.

In the kerbin SOI, I simply put 3 RA-15's outside the orbit of minmus. With all the moons inside the set of relays, they get pretty good coverage, and the RA-15 is strong enough for links with Comm 16s (unless you go very close to the soi edge). I supplement this with an HG-5 on the a polar mapping sat, just to give at least partial coverage of any dead areas near poles.

This is my plane for Duna as well, Jool will require 3x RA-100s past the orbit of Pol.

I also make large ground based arrays of 20+ RA-100s - intending to use them with OPM. In that case, I plan to have a local relay of multiple RA-100's (combined on a single craft) as well for Nedion and Plock communication (maybe Urlum too).

I may not do that with plock though, and I'll just use multiple HG 88's and transmit from the near side.

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I've found that a relay in a highly elliptic polar orbit (with the Pe and AP lining up with the pole) gives a very high percentage of coverage of the body, and any of its moons.  Putting these around a few planets and moons in the Kerbol system, especially if these are stacked Ra-100, or Snark's modded relay antenna, gives good coverage nearly everywhere.  Not necessarily 100%, so planning to ensure capture burns occur within view of Kerbin is a factor in planning.

 

I tend to put these polar relays at Eve and Duna, because they are easy to get to, and quickly add possible paths for comms to go through when the direct path to Kerbin is obstructed

 

BTW, I play extra hard on the comnet, with the only ground station being KSC.  The Keosynchonous satellite above KSC is the most important relay I have 

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25 minutes ago, Birdco_Space said:

BTW, I play extra hard on the comnet, with the only ground station being KSC.  The Keosynchonous satellite above KSC is the most important relay I have 

This really only matters early in career.

Later in the game, the ground network obtained through the buildings is basically obsolete. 250G is not that much compared to this 562G array (I used to thing it was 1000, but I've been told the combinabiltiy exponent is 0.75... so 10^0.75 * 100 = 562)

0BStZOE.png

For the outer planets of OPM, 250 G doesn't really cut it. So I have to make my own ground stations or orbital relay.

Making a massive ground station at KSC is easy, but then its only pointing in the right direction half the time (and there are additional LOS breaking eclipses)

I've thought about assembling other big ground station of kerbin, but it may be easier to just build and even bigger array than what is above, and put it into a very high polar orbit.

Anyway, my strategy is to have just a few, but powerful, relays.

A triangle around a planet and its moons, with the antennas of sufficient power for com 16 connections to the moon/planet. An HG-5 on the polar ore sats just in case.

Massive arrays at kerbin for distance communication (not needed in stock, as an RA-100 pair is good enough for getting to Jool/Eeloo) to the local triangle+ polar orbit relays of other planets.

RA-15's for dres inward, RA-100s for beyond that.

 

Some selected ranges from my spreadsheet:

RA-15 to Comm16 connection (for the triangles): 7.2 "Mun orbit Radii" Kerbin's SOI by contrast has a "mun orbit Radii" of 7.01. So... there 3 can cover the whole kerbin system if placed just beyond the orbit of minmus (approximately 4 mun orbit radii)

RA-15 to RA-15: 1 Kerbin orbit Radii 9What I call a KU)- not really enough for the kerbin triangle to reliably talk to the duna triangle.

RA-15 to RA-100: 4.5 KU. The greatest distance between kerbin and duna is 2.5 KU- It is thus really easy to replace 1 of the RA-15s in the "triangle" with a RA-100 to ensure mun eclipses of Kerbin don't block comminication (Except very very rare events when the RA-100, Kerbin, Mun, and Duna are colinear)

RA-100 to RA-100: 11 KU. Jool orbits at 5 KU, the max distance between kerbin and Jool is 6 KU. We could only encounter a problem when kerbin and jool have the sun between them. Here a single RA-100 in part of the triangle around Duna or Eve should fix that.

Fully-Upgraded DSN to RA-100: 18.38 KU

So now, the outer Planets orbit radii:

Jool - 5 ;  Sarnus - 9.25 ; Urlum - 18.7 *problem* ; Nedion - 30.1 *problem* ; Plock Apoapsis - 49.6 *problem*.

a space based 562 G array to RA-100: 27.5 KU - communicates with an RA-100 triangle at Urlum just fine, but Nedion and Plock are still too far.

Ground/space based 1000 G arrays (22x RA-100s): 36 KU - Will reach an RA-100 and Nedion, no problem. Routine comminication with Nedion (but not constant) is thus relatively easy just by plopping a big array down at KSC.

However, to communicate with a 100G antenna at plock apoapsis, you need a 1894 G array.... which is 51 RA-100s... which IMO is a bit excessive.

adding 4 88-88 antennas (combined mass: 0.4 tons to a probe at plock will allow it to communicate with a 1000 G array at kerbin. To relay to the back side, you need a 4x RA-100 array instead (combined mass 2.6 tons). For plock, I would just use a 1000G array on kerbin, and always land/transmit on the kerbin facing side (if you can wait for the transfer to plock, you can wait for a landing site to rotate to have LOS with kerbin)

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Well, the stock solution for distant places is to set up a 'command center' consisting of a large probe core, a pilot and a big relay antenna. Then you can set up a relay network at the destination normally.

Mod? I'd have to check what mod provided a relay antenna of some rather extreme range I have. Plus non-relay antennas from D-Magic Orbital Science - they are actually experiment devices for listening in for radio signals from deep space, but they can double as non-relay antennas of... I think intergalactic range. I don't think I've seen larger structures in the game. Even USS Enterprise (actual size, from a ship parts mod) could sail around in the bowl of the larger antenna if you could fill it with water. Unfortunately, vacuum operation only, they are really fragile.

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I drop a ScanSat in a high polar orbit of each body before I send kerbaled missions there(to scan for ore and biomes mostly, using all 3 ScanSat scanners plus the stock scanner), with the addition of antenna range, I just started adding a couple relay antennas instead of a couple of 88-88s.

With the relays in place around Mun, Minmus, Moho and Gilly, my Moho explorer vessel was able to spend back data pretty much whenever I wanted to.

I'm a little less confident about my Ike relay being adequate for both Duna and Ike however.(I really should have sent out relays to start scanning Jool by now, possibly even Dres and Eeloo)

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First off, I had a quick look at the equations. As far as I got it, the antenna range is determined by <Range>=<HighestPower> × (<Sum of all Antenna Powers> / <HighestPower>)**0.75 In other words - if you have a vessel with a certain range R, then doubling the antenna(e) will increase your range to 1.682×R.

The communication range of any two given sets if antennae is given by ComRange = (<Range1> × <Range2>)**0.5 - or in plain English: Two identical sets of antennae have a ComRange which equals the Range of a single set. If you increase the range of one set by a factor of 1.682 (i.e. you double the amount of antennae on one vessel) your ComRange increases by a factor of 1.297. If you double the antennae on both craft your ComRange increases by a factor of 1.682, obviously.

The tricky part, however, is signal quality Q which is described by  Q = (3-2×(1-<relative Range>))×(1-<relative Range>)**2, where relative range equals <relative Range> = <vessel distance> / <ComRange> or in plain English, the relative range is the fraction of the possible communication range. Now, no matter what you do, at 50% of your possible ComRange you obtain a signal quality of 50%. The function, however, is not linear, meaning at 25% of the range you still achieve 84% while 75% send you down to 16%.

We obtained that doubling your antennae on one and both vessels will get you a 1.297 and 1.682 boost in ComRange, respectively. This means your relative range of the vessels decreases to 0.77 and 0.59, respectively if their real distance is not changed.

In contrast, assume you would build an additional satellite equiped with the same set of antenna configuration and place it half way in between the two spacecraft. Your real distance is cut to 50%, while the ComRange does not change. Your relative Range is at 50% of what it used to be. However, you now do have two connections on your way to Kerbin instead of just one. The total signal strength is the product of the signal strengthes of the two single connections. Assume your signal strength of the two connections would be 60% = 0.6. Then your overall signal strength would be 0.6 × 0.6 = 0.36 = 36%.

So how does that compare to the original signal strength without relay? Imagine you would operate at 50% of your ComRange and want to improve your signal strength which currently is 50%. You basically have three options: Double the number of antennae on Kerbin to increase your Signal strength to 66.9%. You could double the antennae on your satellite as well which gives you a 79% connection. Great. With one relay satellite in between you get 73.8%. So in this case it would be  best if you increased (doubled) both ends of the connection.

But say, what happens if you operate long distance at 75% of you range (signal at 16%)? Doubling the antennae on both ends gives you an increase to 58.6% while adding a relay in between gets you an amazing 73.6% of total signal strength.

 

As a conclusion we can state that relays are superior to increasing the number of antennae on Kerbin, especially when operating over long relative distances. Especially as doubling the number of antennae on both craft gets exponentially tedious and lets the rocket equation kick in to make that endeavour ever more expensive a single vessel somewhere in space with a few dishes is the best choice.

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Well, the thing about putting a relay halfway between kerbin and your target is.... the rocket equation and orbital mechanics. Half the time, it will be farter away from the destination than kerbin is, so you really need about 4 of them equally spaced to get a reduction in distance. Then you need to spend all that dV to get the multiple relays in position.

In contrast, its really easy to spam relays on kerbin. There is a reason that in real life we have massive arrays of massive dishes on earth on moderate dishes on the spacecraftrt, rather than a series of relay arrays in orbit.

Its also much more versatile than positioning a set of large-ish relays halfway between the origin and destination, for every destination

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  • 2 weeks later...
On 1/24/2017 at 0:55 PM, Fearless Son said:

Duna, baby:  

NYpLJmv.jpg

What's your orbital height and speed on these guys?  I have a contract to place a satellite in a "stationary orbit" of Duna and after the contract completes, I want to move it to set up a relay network like this because Ike is a mean little dude screwing everything up.

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I put "Relay Power Flowers" on highly eccentric orbits around each Kerbin pole, each has 16x of the big stock relay.  I'm sending 2 of them to Jool to be put just outside of Tylo's SOI and canted opposite of Bop's inclination.  Each Joolian moon is getting 2x relay probes with 1 big dish a piece for farside coverage.  Here is the MIRV I'm sending there to deliver it all:

T6scNbO.jpg

 

Each of the MIRV "warheads" has 2 of the relay probes and a polar scanner in the base.  The big booster on then end and the core truss get ditched in to Tylo with some tiny SRBs.

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On 2/6/2017 at 9:00 PM, Railroad said:

What's your orbital height and speed on these guys?  I have a contract to place a satellite in a "stationary orbit" of Duna and after the contract completes, I want to move it to set up a relay network like this because Ike is a mean little dude screwing everything up.

Lower than Ike, clearly.  

I do not have the exact numbers on me at the moment, I had to estimate the orbital height, but got them into a resonant orbit with each other by using multiple maneuver nodes and closest approach markers.  One thing that I did know going in though was to not bother trying to get into geosynchronous orbit around Duna.  Ike makes that all but impossible since it Duna's geosynchronous altitude falls within Ike's SOI.  They had to be close enough to Duna that Ike was well out of the way, but far out from Duna enough that each could trace a line of sight to the other two over the horizon.  

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1 hour ago, Fearless Son said:

One thing that I did know going in though was to not bother trying to get into geosynchronous orbit around Duna.  Ike makes that all but impossible since it Duna's geosynchronous altitude falls within Ike's SOI.

Could someone just put relays in the same orbit as Ike? They wouldn't be precisely Duna-stationary but at least Ike wouldn't mess with them.

Once in a 1.0.5 career I got a contract to do something similar; set up a sat above a specific point on Duna. Never got that far, but the specific point wasn't near Ike's point in the Duna sky.

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2 hours ago, Gordon Fecyk said:

Could someone just put relays in the same orbit as Ike? They wouldn't be precisely Duna-stationary but at least Ike wouldn't mess with them.

Once in a 1.0.5 career I got a contract to do something similar; set up a sat above a specific point on Duna. Never got that far, but the specific point wasn't near Ike's point in the Duna sky.

I am curious about this too, but I was not about to try in career mode.  Though considering that Ike is tidally-locked with Duna, you could get one of the three points of the relay to be a surface base on the Duna-facing side of Ike, then put two satellites in the same orbit for the other two points.  

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4 hours ago, Fearless Son said:

I am curious about this too, but I was not about to try in career mode.

Ahh the joys of sandbox and cheats.

I cheated a launcher that I used to set up a trio of sats around Kerbin, around Duna following Ike's orbit, and it seems to work. Though I reviewed Ike's AP and PE to make sure I got the orbits right, and found that the KSP Wiki needs updating.

Ike's AP and PE, as of 1.2.2, are 2976.000 km and 2784.000 km respectively. I took video of this to make sure and maybe I'll cut and post it later.

With that info, I put my cheated craft into low Duna orbit and into Ike's orbit plane, and placed it directly across Duna from Ike. After matching orbits as closely as I could with the launcher's Rhino engine, I deployed the first sat at Duna AP and made adjustments with their smaller engines. After following the launcher around to Duna AP again, I deployed the second sat and reduced its orbital period from 3.0 days (uncanny, huh?) to 2.0 days, which put it between Ike and the launcher, then reset the orbit at AP. I repeated these steps with the third sat, then crashed the launcher into Ike to appease it and hopefully discourage it from eating my sats.

I did further adjustments using Ike as my target and fixing up the AN and DN nodes.

DunaSynchOrbit.png

This was the end result. I ran time ahead a few months to make sure Ike didn't mess with them, and it seemed OK.

So as long as I matched Ike's orbit but changed the spacing, I could put relays in Duna-synchronous, if not Duna-stationary, orbits.

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