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Simplest communications setup


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What communications relays do you put in place when planning to visit another planet?

I've planned, and occasionally even launched, elaborate constellations for previous planned visits, but in my current career save I've got the funds rewards turned right down, and I'm wondering what little I can get away with, with my first Duna window coming up.

I was considering launching one powerful relay, which can reach back to Kerbin, into and eccentric orbit above the north pole, with a smaller in-system relay to detach and put into a similar orbit below the south pole. Then my main science probe/lander can go into an equatorial orbit, and drop off a similar small in-system relay to run around an equatorial orbit.

I think that should mean that the three relays will always be able to see each other, and between them they will cover most of the surface most of the time.

Is that already over the top? Have I missed something that I'll regret instantly when I try to land?

Thanks

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To some extent, it depends on just how complete you are determined to be for the science.

Duna and Ike are tidally locked. Which means the same face of Duna and Ike always point toward each other. Which means that if you have a relay landed right in the middle of the Duna-facing side of Ike, then you are guaranteed to always be able to see it from the Ike-facing side of Duna. Which is half the planet. So, 50% permanent coverage with just one relay. Which should be able to see Kerbin 50% of the time. If you put a strong direct antenna on your Duna lander, then you will have a direct signal to Kerbin for something like 25% to 50% of the rest of the time, when the relay is in a comm shadow. So as far as I'm concerned, that's a heck of a lot of coverage for one dinky little relay that can even gather some Ike science while its there.

 

 

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Relay coverage requirements depends on several things:

1) Your communication settings determine how many overlapping relays you might need. With default settings, a probe can see a relay even if it's slightly under the horizon. I'll often put a pair of identical relays in highly elliptical polar orbits above Duna, 1 above each pole. That covers the entire surface with only short blackout periods as a relay goes around periapsis. I prefer a pair of polar relays to a trio of equatorial relays, because the polar relays can be put into slightly sloppy orbits while the eq trio has to be carefully synced so all 3 orbital periods are identical.

2) Your probe control settings determine whether uncrewed missions can tolerate short blackouts. Default still lets you activate max throttle to get a rough orbit during a blackout, so your probe doesn't shoot past Duna. You can fine tune the orbit later when you have a comm link that lets you use precise throttle controls.

3) Do you like to "wing it" or do more careful mission planning? Loss of communication during a probe landing can be fatal. If you want to be able to land without much planning you want more relays to guarantee continuous coverage. If you like planning and are patient, probe landings can be done with just a single relay in orbit.

One way to build up a comm network over time is to include a relay and probe core on every new transfer stage. You'll gain an orbital relay for every new lander mission you send to Duna. When you have "too many" relays at Duna, find an old transfer stage with extra fuel and relocate it to Ike.

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Well, the simplest communication setup is strong enough direct antenna in the craft and planning/hoping to not lose contact at some critical moment. The question is if you can afford that risk. (Giving the question, I assume you are not exactly willing to do so).

 

10 hours ago, eatU4myT said:

I was considering launching one powerful relay, which can reach back to Kerbin, into and eccentric orbit above the north pole, with a smaller in-system relay to detach and put into a similar orbit below the south pole. Then my main science probe/lander can go into an equatorial orbit, and drop off a similar small in-system relay to run around an equatorial orbit.

 

That seems like a more elegant setup than what I do: spamming Gap Relays:  cheap probe core,  HG-5 antenna and  solar panel.  And, if available*, I use remote probe control points* instead of long range relays. If you want to try something even more elegant consider a single relay in Tundra_orbit.

 

 

*There are mods that provide it quite early.

**for Moho, Duna/Ike, Dress and Eeloo an HG-5 in the control point is enough. Eve/Gilly can be covered with an RA-2

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Comma networks depend heavily on what tech you have unlocked and your tracking station upgrades- with a level 2 tracking station you’ll need several RA-15s to reach back from Duna (and to a lesser extent Eve) to Kerbin but with a level 3 TS it’s easy to do with a couple of RA-2s or a single RA-15. Landing relays on tidally locked moons like Ike or the Mun seems like a good idea, but since they’re landed half the sky is blocked by the surface and for Ike that makes it harder to link up with either another relay or directly to Kerbin.

A couple of potent relays in really high polar orbits will provide a connection back to Kerbin under (almost) all circumstances, so other probes/rovers or crewed missions don’t need such large antennae to connect to those and can save mass, cost and space with smaller ones. Ike does pose a threat to anything orbiting Duna so stick with really high orbits to avoid it; for relaying around Jool one or two really powerful relays in polar orbits of Jool and smaller relays around each moon will probably be the best strategy. Including a relay fish on any crewed mothership will also help increase your coverage for surface missions.
 

A few big relays between planets can also help relay the signal and avoid blockages caused by other planets or moons, although it’ll cost a lot of fuel to get them into place without the help of a planet’s gravity well.

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