Question

So, I haven't been very active in KSP since last year, and only dabbed a little bit once the comms were introduced. Well, just yesterday, I attempted a Duna mission with a probe only in career. I had a pretty big commsat setup in the Kebrin system. And yet while I still had some control on the approach of Duna (even during the Aerobraking phase) I had completely lost comms with my probe after I left Duna's atmosphere. Let me begin by saying that since this last time I restarted career mode, this was the first probe ever in the Dunian system. I tried to wait for one more aerobrake after I lost control and I still didn't get my comms back online and I had totally lost the probe. Gosh, it felt like a scary mars mission blowing millions of USD for nothing.

 

Anyway, what is the best approach of an unmanned mission to a new world for the first time? Is there anyway to maintain that control without a commsat setup already in place? It's very different trying this with the comm networks now, and exploration seems even harder now. Not that I mind the challenge, but I have a laythe probe already on the way even before my Duna mission and I am afraid I will not be prepared for it by the time it reaches the Joolian system. How do I prepare unmanned missions with the commnet, and what steps should I take before sending a probe to unexplored worlds so that I do not lose it like I did with my Duna mission?

 

**EDIT**

Yes, I have upgraded my tracking station to the max. It is fully upgraded.

Edited by Der Anfang

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You should be able to regain comms unless your antenna broke during aerobreaking or you forgot to redeploy it. If you want comms at all time, you need Commsats around Duna, but loosing communications while behind the Horizon is usually no big deal.

Is the antenna strong enough for duna? 

What level is your Tracking station? Upgrades enhance the strength of your groundstations signifficantly.

A comment around Kerbin will usually not help you with interplanetary missions because your Satelites (unless they have ridiculously many antennas) won’t be as strong as the grounstations, so any probe will connect to the groundstations directly.

Edited by Physics Student

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what i use to do was build the space craft that would fly there, then build a small relay and add it to a decoupler on the craft. once i got a good orbit at the planet or moon i want i would decouple the relay antenna probe and begin my landing burn. the probe will be above you so landing  should not be  an issue unless a moon or another planet is in the way.

then when you want to leave just  wait till the probe is above you again and take off.

do a few practice runs using alt f-12 on the mun and see how it works.

 

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Well, if you don't have any commsats around Duna, you won't have a signal when Kerbin is below the horizon of Duna (or simpler: not visible).

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As said above, it's best to have the relay at your destination -- not at Kerbin. Or at least halfway to your destination. Or in a higher orbit than your destination. And the relays don't need to be hanging around a planet -- they can be out in the middle of space somewhere. So just shoot a small, fast relay off in the general direction of the ships you have en route.

 

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Best thing is to set up one or two comsats. Note that normal antennas do not combine with relay ones. So use relayantennas only.

Best orbit for a comsat is a high excentrical polar orbit. Why? The polar approach ensures that you have line-of-sight to Kerbin when burning the Duna orbit insertion. While high over a pole the sat will move slow and will stay a long time above or below, providing a line-of-sight to other vessels.

Note that the ground stations at Kerbin are way more powerfull than any relayantenna in the game. Note also that the power of the groundstations depends on the level of your tracking station.

If you rightclick a relayantenna in the VAB/SPH there are shown 3 values of range: L1, L2 and L3 - that means against a level 1, 2 or 3 tracking station. 

 

If your probe still has a functional antenna and electric charge upgrading your trackingstation may solve your actual problem. 

 

As comnet is new for you i want to note also that there is a thing called "advanced tweakables" in the settings now. Check that they are activated. Chutes have now the option "deploy when safe". You can arm them on your probe while in space and have line-of-sight and they will deploy at the right moment, even if you are out of l-o-s. Chute parameters should be min. pressure and full deploy at highest pos. altitude for Duna.

Search the forum for "fuel priorities", another great new thing with advanced tweakables.

Last not least take a look at the new science part, the container. It equals a kerbal taking data on EVA and store them into the pod. Nice thing to recover data uncrewed on Kerbin - there is a new 0,625m heatshield too :wink:   ---- Did i mention that probe cores do have a hibernation mode now? I didnt? Well, thats because it would be a completely new topic :wink:

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Line of Sight is necessary for communication.  If you don't have relays, try to stay in the near side (relative to Kerbin) for the necessary maneuvers. And have some extra fuel for the eventual unavoidable occlusion and adjustments.

If you are going to aerobrake, I recommend the Antenna Sleep mod. (IMHO should be stock)

If you have the [requires signal for control] option disabled a probe without communication can still orient itself with SAS and you can burn at 100% throttle.  

 

 

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Lots of solid advice in this thread. My only addition is, if you're unsure if you'll have comms, a quick way to test is to put your ship on the launch pad, alt-f12 and change it to be orbiting the destination world, then revert so it never actually happened. 

Edited by 5thHorseman

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Yep, just to summarize:

On 10/15/2017 at 1:34 AM, Der Anfang said:

Anyway, what is the best approach of an unmanned mission to a new world for the first time?

Solving your problem depends on what your problem is.  There are two main reasons why you may be losing comms:

  1. You just don't have enough oomph in your antennas, and they can't reach between Kerbin and your destination.
  2. You're getting occluded by the planet.  e.g. your probe is moving around behind Duna (as seen from Kerbin), so it doesn't matter how powerful your Kerbin network is because Duna's in the way.

(There's also a third possibility, "plasma blackout", if it's during aerobraking that you're losing comms.  But I expect that's probably not the case here, since that option is turned off by default unless you've turned it on, and also it's a very temporary thing that only applies during the fastest/hottest part of reentry.  So I'll assume this isn't it, here.)

Solving your problem vitally depends on knowing which of the above two things is your problem, because they're completely different problems and would have completely different answers to your solution.

So we need more info from you, to tell whether problem #1 may be the case:

  • What kind of antenna (or antennas) do you have on your probe?
  • What level is your tracking station on Kerbin?
  • Do you have "additional ground stations" turned off?   (If you don't understand what that question means, the answer is "no".)  :wink:
  • What kind of antennas do you have on your Kerbin-centered network?

 

If the problem is #2-- and I'm guessing that's what your issue is, here, but that's just a guess-- then what you need is some way of maintaining a connection back to Kerbin when Duna is getting in the way.  In practice, what that means is that you need a relay satellite that's not around Kerbin, that your probe can bounce signals off.

Lots of ways to do that.  Easy way #1:  your Duna ship also has a relay satellite that decouples upon arrival at Duna and stays in orbit, as @invision suggests above.  Easy way #2:  Scatter a few powerful relay satellites around the solar system, so that your Duna probe can see them even when it can't see Kerbin.

(Note that solution #2 will generally need more powerful relay antennas than solution #1, for reasons involving antenna math that I won't go into unless you're interested.  The simple boiled-down answer is that solution #1 only needs a relay sat powerful enough to talk to Kerbin, which doesn't have to be too strong because Kerbin's so powerful; but solution #2 needs a relay powerful enough to reach the probe over a distance of many millions of km, which needs a beefier antenna because the probe's antenna is likely wimpier than Kerbin's.)

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