how do i modify my satellite network so that i can have zero downtime flying a probe?

[lammatt]

how can i modify my current setup in order to afford a zero down time for a probe (with one antenna only) orbiting sun?

- i can have zero downtime now with 3 antennas on the probe but how can i do so with only 1 antenna?

[Drew Kerman]

you can't. If you're doing anything beyond Minmus (which is what I interpret as "orbiting the sun")you need at least two additional probes in polar orbits so that they can relay signals from above/below the orbital plane. Otherwise while traveling within Kerbol's SOI from planet to planet (or to Kerbol itself) you will run the risk of a planet getting in the way of your signal.

[lammatt]

so does it mean, i have to put two probes into coplanar polar orbits,

and then relay my signals from the KSC, to the equitorial ones, then to my active vessel?

- but the polar probes will sooner or later run into the dark side of the planet, wont it?

[vger]

Wow... have I somehow missed something about this game? I have never lost contact with a probe. Is it just because I managed to cover target worlds with enough of them before worrying about constant contact? Or is this a mod-related question?

[Drew Kerman]

put the two polar probes into highly elliptical orbits, that way one can get high above the orbital plane while another goes below, and both spend a very short amount of time behind the planet as they will be moving very fast at that point. You can set it up so one is at the top of its orbit while the other is at the bottom. I will eventually have this same network setup, currently working to get my third equatorial satellite in position. make sure you have VOID installed so you can see your orbital period and semi-major axis values and be able to match the 3 equatorial probes so they don't lose position too much over time. It will be hard to get it exact, unless you go into the save file and manually make the values exact. I'm just getting it close and setting an alarm in Kerbal Alarm Clock to check up on them once every 30 days or so - plenty of RCS thrust to make adjustments over time as needed.

Also with this setup there's really no need at all for a GSO satellite. The 2.5Mm omni antenna will work just fine on all your sats and then dishes on those sats can be used to reach outside of Kerbin's SoI.

Edited March 30, 2014 by Gaiiden

[Deathsoul097]

Wow... have I somehow missed something about this game? I have never lost contact with a probe. Is it just because I managed to cover target worlds with enough of them before worrying about constant contact? Or is this a mod-related question?

This is a mod question. The OP is asking about setting up relay sats for Remote Tech 2, and a mod should probably move this to the appropriate subforum.

[Starstrider42]

how can i modify my current setup in order to afford a zero down time for a probe (with one antenna only) orbiting sun?

- i can have zero downtime now with 3 antennas on the probe but how can i do so with only 1 antenna?

http://i.imgur.com/JmUBySC.jpg

The polar orbit method is WAY more complicated than necessary, especially since you'll have a hard time targeting both with the same antenna if they have an extreme apoapsis.

Here's a simpler approach, requiring no extra launches: once you're far enough away that the equatorial satellites' orbit fits inside your antenna's cone (about 3-4 million km, if you're using the Communotron 88-88 or Reflectron KR-14), point the antenna at Kerbin (not at one of the satellites). There will always be at least one satellite inside the cone and not behind Kerbin.

[Drew Kerman]

There will always be at least one satellite inside the cone and not behind Kerbin.

Yea, so long as you don't have anything between you and Kerbin. That's the problem the polar satellites fix

[Respawn]

I'm messing around with rss and rt2 atm, and i had a similar problem.

The sun got in the way just as i was about to do my capture burn.

However my plan to get around the problem is to set up 2 relay stations at (what would be) L4 and L5 of the kerbin-kerbol L-points.

60º ahead and 60º behind kerbin in it's orbit.

I know the game doesn't simulate Lagrange points but those two points are stable sun orbits in the game and i'm allowed to pretend. ^^

[Hodo]

I found it useful to have 3 layers of satellites for a 99% coverage.

One section that is my low satellite network, which was at 250km orbit there were 6 of them, 3 are required but I had 3 for reduntancy.

Then I had the standard GSO network way above the base layer.

The last layer was the 6 more satelittes I had in a polar orbit. I had 3 in one polar orbit then another 3, 90deg off from those three in the same orbital alt as the low alt coverage network.

I think it gave me a total of 16 satelittes in orbit. But I had coverage all the way to Eve without interuption from Kerbin, except when Eve was in the way.

The only problems I found with this network is other planets and moons. The Mun and Minimus will occassionally interupt signal flow for a few minutes to an hour. But its not that bad if you plan for it. You can get around this by putting a network around the moon.

Edited March 30, 2014 by Hodo

[Amaroq]

I think you have the gist of things, here. The same concepts apply at just about each body you need to potentially work around; a triad of satellites 60-degrees off from each other should do it; at least one satellite in a low polar orbit will help to cut down your transmission times. Using "aim at the body" lets you pick up "whichever satellite near that body is talking to me", and should be used liberally to make use of any network redundancy you have.

[wmheric]

so does it mean, i have to put two probes into coplanar polar orbits,

and then relay my signals from the KSC, to the equitorial ones, then to my active vessel?

- but the polar probes will sooner or later run into the dark side of the planet, wont it?

Yes, you're right. Molniya orbits are for reducing the down time by lowering the proportion of time a probe spends close to (and behind) Kerbin, the relay satellite eventually goes into the "dark" side from time to time anyway. IMO Molniya constellations are much more tedious to set up/maintain/upgrade, and I always use equatorial circular orbits for relay outside the Kerbin system, unless I want low-orbit or ground coverage in the polar regions.

I'd like to talk more about the single-antenna case, as the OP tries to use.

...but how can i do so with only 1 antenna?

A simple answer is no, you cannot. You'll need at least 2 antennas to guarantee zero down time anywhere in the Kerbol system.

But as I often did, you can keep the probes with only one dish pretty safe if the down time is small. You can calculate the portion of the orbit in the "shadow", or more precisely, the angle (theta) that the "shadow" subtends with respect to the center of Kerbin:

sin (theta/2) = R_K / r

where R_K = radius of Kerbin = 600 km, and

r = radius of the orbit (now we only look at circular orbits)

(Here we assume that your probe is far away from Kerbin. You can treat "far" as the distance being much greater than R_K.)

From a period T = 2 hr given in your sketch (nice use of the compass!), the corresponding radius (the distance from the center, not the altitude) of the orbit is r = 1667.6 km, and the angle subtended is 42.2 degrees, or 11.7% of the orbit, so the down time is 2 hr * 11.7% which is about 14 min. Moving a maneuver node 14 min ahead/behind is not really a big deal compared to the whole interplanetary flight. It might become an issue in critical moments like a capture burn / landing, but you can always plan ahead to arrive earlier or later.

On the other hand, as Starstrider42 has pointed out, if the probe gets far enough away from Kerbin, you can switch the pointing to a single satellite to just Kerbin (always quicksave first…) and still have the dish covering everything, and now you have zero down time! The distance (d) required can be found in a similar way:

tan (theta/2) = r / d

where theta = cone angle of the dish, and

r = radius of the orbit

For example, for a Communotron 88-88 dish, theta = 0.06 deg, using r = 1667.6 km, we get d = 3185 Mm, which is smaller than the semi-major axis (5263 Mm) of Moho, or even the closest Eve can ever be from Kerbin (~3700 Mm).

(I hope I didn't make any mistakes, but I think you can figure out the geometry by yourself It works similarly for other planets as well!)

Edited March 31, 2014 by wmheric

[iStickyDuck]

Send small relay probes to every planet and moon in the Kerbol system that way, you will never lose connection

[federally]

Use the flight computer to pre program maneuvers into the probe. As long as you are connected when you tell the probe which way to point and when and how much to burn the probe will perform the maneuver with absolute precision regardless of whether or not you have signal.

Then make sure you do complex maneuvers that require you to have direct control while not in the shadow of the body you are orbiting.

The flight computer really lowers how much of a network you need to build.

[8749236]

Theoretically with only 3 sat it should work...

But the problem is you can't make them goes like a clock that each of them takes exactly same time or orbit around the kerbin...

At least I cannot make that happens... It always somehow has some slightly time variance..

So instead I launched 20~ probes for a full coverage with various orbit...

Then fired long-range-com specialized probe for that...

[lammatt]

Theoretically with only 3 sat it should work...

But the problem is you can't make them goes like a clock that each of them takes exactly same time or orbit around the kerbin...

At least I cannot make that happens... It always somehow has some slightly time variance..

So instead I launched 20~ probes for a full coverage with various orbit...

Then fired long-range-com specialized probe for that...

you can

there is thousands of data readout mods.

same semi major axis, same T.

[8749236]

you can

there is thousands of data readout mods.

same semi major axis, same T.

How do I do it?

I can't even do it with mechjeb..

unless i play around with sfs...

[Drew Kerman]

RCS - normally you have many quads spaced around. Disable all but one and activate precision controls (caps lock I think is the default key binding). Or, if you want to use a liquid engine right-click and dial back the thrust output. Then it's all about small, careful adjustments. Personally I keep mine like 0.01 second diff between orbital periods so I have to adjust every now and then just like real satellites (and the ISS) do

[lammatt]

How do I do it?

I can't even do it with mechjeb..

unless i play around with sfs...

CAPSLOCK and rcs

mehjeb offers a reading of the s.m.a corrected to 7 digits

Edited April 1, 2014 by lammatt

[8749236]

RCS - normally you have many quads spaced around. Disable all but one and activate precision controls (caps lock I think is the default key binding). Or, if you want to use a liquid engine right-click and dial back the thrust output. Then it's all about small, careful adjustments. Personally I keep mine like 0.01 second diff between orbital periods so I have to adjust every now and then just like real satellites (and the ISS) do

I guess that's just me..

Tried that and it still does not work very well =S...

But yeah, definitely works for years >_>..

Maybe I am just worrying too much...

[Renaissance0321]

You guys that are launching tons of probes to cover everything around Kerbin are not doing this efficiently. You only need 3 sats in geostationary orbit around Kerbin EVER. Use Scott Manley's tutorial on how to place them 120 degrees apart at the right altitude. For sats around other planets it's not possible to have 100% coverage unless you also make 3 sats in geostationary orbit around that planet or moon.

[mecki]

You guys that are launching tons of probes to cover everything around Kerbin are not doing this efficiently. You only need 3 sats in geostationary orbit around Kerbin EVER. Use Scott Manley's tutorial on how to place them 120 degrees apart at the right altitude. For sats around other planets it's not possible to have 100% coverage unless you also make 3 sats in geostationary orbit around that planet or moon.

Guess you are right.

But would the 3 satellites necessarily have to be in geostationary orbit? They could also be on a lower orbit, just high enough to see each other.

And the idea of 2 satellites in polar orbits with high apoapsis sounds like it would make sense…

[rkman]

Send small relay probes to every planet and moon in the Kerbol system that way, you will never lose connection

Right, that is how NASA does it: 3 big ground stations on Earth, relay sats around planets of interest. No relay sats in Earth orbit. Although it does not guarantee 100% coverage either, it is a lot more convenient than managing a bunch of relay sats in Earth orbit.

[MarvinKitFox]

Right, that is how NASA does it: 3 big ground stations on Earth, relay sats around planets of interest. No relay sats in Earth orbit. Although it does not guarantee 100% coverage either, it is a lot more convenient than managing a bunch of relay sats in Earth orbit.

Aside from the network of TRDS sats, you mean?

http://en.wikipedia.org/wiki/Tracking_and_data_relay_satellite

[rkman]

Aside from the network of TRDS sats, you mean?

http://en.wikipedia.org/wiki/Tracking_and_data_relay_satellite

Not used for anything outside of LEO.