How many hours of darkness does the Mun get?

[Kimberly]

I want to land a base station at the Mun's equator, which will receive RemoteTech satellite dish signals from two communication relays in orbit around Kerbin. It will then transmit the signal to satellites orbiting Mun, via antenna. The base station would always be pointing towards Kerbin, seeing as Mun is tidally locked, and the satellites are spaced evenly apart so at least one has a clear line of sight to Mun at any time.

The issue is providing power to the station. I want to do it with solar power, but that presents a problem. The base station would be pointing away from the sun for at least half of its orbit, and Kerbin will eclipse the sun regularly as well. Can anyone give me an estimate of how many hours of darkness I should count on? I need to know how many batteries to put on the base station.

Edited July 9, 2013 by Kimberly

[GJames]

I believe it's about 3-4 hours, but a few RTG's should help.

[Xaiier]

Half of the Synodic orbital period - 139812s, assuming your base was zero height on a perfect sphere of a Mun.

Realistically there will be loss/gain due to the terrain elevation around you as well as the loss for the eclipse.

[Lord_Zord]

The Mun makes one rotation in 138984 seconds = 1 day 14 hours 36 minutes 24 seconds.

So the night is half that, which is 69492 seconds or 19 hours 18 minutes 12 seconds.

(Assuming you are at ground level and no hills are blocking the sun)

From the wiki.

[Xaiier]

The Mun makes one rotation in 138984 seconds = 1 day 14 hours 36 minutes 24 seconds.

So the night is half that, which is 69492 seconds or 19 hours 18 minutes 12 seconds.

(Assuming you are at ground level and no hills are blocking the sun)

From the wiki.

The mun makes one rotation (and one orbit) in that time, but in that time Kerbin has moved along the path of the sun so the sun comes up on your Mun base 13.8 minutes (828 seconds) after one Mun orbital period.

[Kimberly]

So I should count on 70320 seconds of darkness, then, plus eclipses? That's great, my current design gives me 76661 seconds of power! And my two solar arrays will recharge the battery in 208 seconds, which should be more than enough to make use of pre- and post-eclipse sunlight. Thanks for the help, everyone.

My current design:

The part the solar arrays are attached to is the battery, which holds a charge of 7500; it's pretty powerful, but weighs a lot as well. (And it's the only one in this size I had.) I intend to attach a small rover to the bottom docking port when deploying it, and later if I can I'll lift up the station with KAS and attach it to a manned structure, so it can use the RemoteCommand module it has to direct moon missions.

Edited July 9, 2013 by Kimberly

[JelloTickles]

Get RTGs dude

[Kimberly]

Get RTGs dude

Engineering is not about doing things in the easiest possible way. It is setting a goal, and designing something that will help you achieve that goal. It is nothing less than bending the very fabric of time and space to your will!

[msyblade]

RTG's are more efficient for your needs than solar panels + 1600 worth of batteries. Engineering is more about functionality and efficiency, without needing to bend space or time to your needs. RTG's can even be laid flat on most surfaces, in symmetry, if it is an aesthetic concern you have. Just my 2 cents, I prefer solar panels in space (mostly an aesthetic choice, rather than engineering), and RTG's for planet bound craft.