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Avoiding probe deadlock without tracking panels


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TLDR: What's the best method to avoid a probe running out of electric charge (and therefore becoming uncontrollable) over long durations of not monitoring it if you only have static solar panels?

I've recently sent a probe to Moho and I did so with less tech than I would have liked because the transfer window was there and it seemed exciting to try. I'm now getting concerned though because it will be on a long voyage and the static solar panel may move away from sunlight while I'm not watching and then I will lose the ability to control the probe.

I have two batteries, and I just tested a theory I read online that said you can deactivate one so that if you come back and the rest is depleted you can simply activate the full battery. My experiment showed that this doesn't work, because once the probe is out of electric charge you can no longer activate that battery remotely, so you're really just losing more buffer.

I have tried activating SAS while facing the sun (risky I know, since it uses even more charge, but if it guaranteed sun facing it would of course be worth it). Unfortunately some limited testing suggested that this doesn't necessarily work over long periods. This also wouldn't work with the round probe that doesn't have SAS.

My best idea so far is to use the reaction wheel to set the probe into a slow diagonal spin and leave SAS off. This gives a big arc within which the the static panel will catch at least a few rays on occasion, thus making the only 'deadzones' for the panel when the probe is perfectly perpendicular to the sun, which is very unlikely to happen and unlikely to stay that way for long. Other ideas would be appreciated!

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I generally face the probe normal or anti-normal. They should stay in that orientation and have their side mounted panels facing the sun throughout their orbit.

I'm pretty sure spinning won't help in the stock game since it gets cancelled when you timewarp or when the ship is placed on rails when you return KSC.

 

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4 hours ago, Snark said:

My most common setup is 4-way symmetry.  It's hard for them to be completely occluded unless the axis of the ship is pointing perfectly through the sun.

I do something similar (until I get PB-NUKs, then I rarely use solar power again) but I mount them in pairs and give them a one-click rotate so that they have at least a bit of the panel in light if the craft gets inline with the sun forward or aft...

4rtWT7F.jpg

Edited by Foxster
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2 hours ago, Zo San said:

I have two batteries, and I just tested a theory I read online that said you can deactivate one so that if you come back and the rest is depleted you can simply activate the full battery. My experiment showed that this doesn't work, because once the probe is out of electric charge you can no longer activate that battery remotely, so you're really just losing more buffer.

This used to work, but it really wasn't a "feature" as much as it was an oversight. It was fixed when 1.1 came out, so no, you can't do that any more. 

As for the rest of it, I agree with @Reactordrone. Put your ship so that it's pointing Normal or Anti-normal. That way when the ship naturally "rotates" it will appear to spin on it's long axis and thus hopefully always have at least one panel pointing towards the sun. 

I think the rules for electric power generation and consumption change if you're controlling the ship versus if you're flying something else or if you're in the Tracking Station at KSC. You might try redoing your tests, but instead of going into time warp while controlling the ship, go to KSC and time warp from there. 

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Your post makes it sound like you only have one solar panel? I kinda hope you have two, at least. But the main point goes like this: as long as you are not watching the probe, it does not use any power. It only uses power when the ship has focus. So, if you make sure your batteries are all charged when you switch away from the ship, then they will still be all charged when you come back to it. The way to kill a battery is to not pay attention to whether your solar panels are getting any light, and then timewarp. So, for a probe, make it a habit that the first thing you do is always point one of the solar panels at the Sun.

The trick with disabling a battery was cancelled with version 1.1.

There is a request in the bugtracker for some kind of standby mode for probes, that will stop them from using electricity -- we will see if that gets implemented in some near-future version.

Yes, your rocket will drift slightly off-line over time. I just recently had a probe in Minmus orbit end up pointing tail-first at the Sun with drained batteries (I timewarped). I had to wait half an orbit for the probe's orientation to change a little bit, so that I got enough power to start a tiny rotation -- which got me more power.

As Reactordrone said, if you point your probe north or south, then it will automatically rotate slowly as it goes around its orbit. You can still end up with short periods where you have no incoming solar power, though.

 

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Thank you for the responses! You're right, I noticed when I came back to my probe that I had set to spin it was no longer spinning - a bit of a shame that the rotation isn't tracked but I understand that would probably be a performance hog. This probe I've got going to Moho has the static panels on one face only (a design oversight from focusing far too much on engines, ascent, orbits, etc and not enough on the important utilities layout). I guess I will have to keep an eye on it for... a long time :(

I have some cheap satellites that do have the panels on several faces though - will try the normal orientation on those. Thank you for the recommendations.

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Whoops, posted at the same time as you bewing so I missed your response earlier. That's really good to know that they don't waste charge when they're not in focus/flight mode and makes all of this a much smaller deal than I thought it was.

I do have two panels on the probe but sadly both facing the same direction... not entirely sure what I was thinking when I built this craft but I sure will be changing the design drastically before launching any more like it haha!

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The fact that no electricity gets used when it's out of focus makes things a lot easier.

My minimal solar panel setup is 3 panels in tri-symmetry, which works out nicely in early game when my go-to probe core is the HECS.

My most common setup is 4-way symmetry.  It's hard for them to be completely occluded unless the axis of the ship is pointing perfectly through the sun.

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30 minutes ago, Epox75 said:

If you are into mods Persistent Rotation might be what you are looking for. 

 

Forgive me for nitpicking, never tried the mod,  but seems to me that one may still run dry.:  Forget  SAS on,  ship stop rotating with solar panels facing away sunlight,  end up with no EC.  Correct me if I'm wrong.

If I understood correct still is the positioning that solves the issue,  granted that the mod make it simpler.

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2 hours ago, Spricigo said:

Forgive me for nitpicking, never tried the mod,  but seems to me that one may still run dry.:  Forget  SAS on,  ship stop rotating with solar panels facing away sunlight,  end up with no EC.  Correct me if I'm wrong.

If I understood correct still is the positioning that solves the issue,  granted that the mod make it simpler.

It's actually SAS that activates the mod and body relative rotation is the option you are looking for. For instance if you are in orbit around Kerbin you can choose either the Sun or Kerbin as reference body. If you choose the Sun, engage SAS and activate the relative rotation option, your spacecraft will always face the Sun.  And the mod makes also possible the use of gravity gradient stabilization even during time warp. Also this option is activated engaging the SAS

Kerbalism is also a very nice mod but it make the game more difficult and frustrating sometimes, thou it keeps track of the EC of all your spacecrafts, inform you if it's dropping too low and even automatically deactivates all the EC demanding parts and reactivates them as soon as the charge is back to a reasonable level. 

Edited by Epox75
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Never had issues with two panels except then I placed them on an MK1 pod sides and the engine pointed towards the sun. Luckily the pod was manned so kerbal went eva and rotated it. 
however I tend to use 3 panels on probes who don't need the tracking ones around kerbin, you can use solar out at Jool however here you need multiple tracked just for probe functions, 

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6 hours ago, Spricigo said:

Looks like I stand corrected. This mod is leaving my "interesting but not necessary"  list and entering "deserves evaluation"  list. 

SAS in this mod, doesn't make your ship stop rotating. It makes your ship rotate and face a selected body... always. Just try it :) I've started looking for this mod because I had a problem similar to yours. 

Edited by Epox75
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My preferred method of dealing with small probe power is mount several fixed solar panels radially, with a minimum of four.  These might not be "optimal" in terms of mass to generated power, but they are so light and so rugged that unless the probe is a power-hog they are generally sufficient to keep it operational.  All you need is just one small panel to be facing the sun, even obliquely, for your probe to function.  Admittedly, it might not charge very much at such an angle, but it only needs a little bit of charge to get the probe core going, and the probe core can run the reaction wheels just enough to orient the craft for better electricity generation.  

This only works well for smaller probes that do not have substantial power requirements, but if you are building big probes that require lots of power you are better off waiting until you get more advanced electronics anyway.  

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De-activating batteries and activating them again when the spacecraft is dead no longer works in 1.1.2. It was my preferred method to have a backup in case of electric starvation.

Orientating the craft Normal or Anti-Normal (point the nose north or south) and putting 3 solar panels in radial symmetry on the craft makes sure that a little bit of solar panel is always pointing to the sun. That's what I always use.

I haven't tested is entirely but I think that spacecrafts that are on rails don't use any electric energy in 1.1.2. If not, most of my probes are dead by now because they don't have enough battery to stay alive while they are in their parent body's shadow.

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