Most Efficient Munar Orbit for Kethane Scanning

[Magmaros]

Hey guys, what sort of orbit should I be looking for height wise and inclination wise to map out the Mun in the least amount of time?

[CosmicGamer]

Well for the least amount of time im not sure all i know is in an almost polor orbit along the line where light turns to dark you will eventually map the whole planet with no power loss

[Spica]

I would go for a polar orbit of approximately 30 km in hight, however, since i don't play with the kethane mod that much, I may be wrong.

Spica

About CosmicGamer's claim that there will be no power loss in a polar orbit, not to be rude, but that is wrong. Eventually, the mün will have orbited around kerbin by about 90 degrees, your orbit will periodically dip into the mün's shadow. You will also have to periodically have to adjust your spacecraft's orientation to be pointed at the sun.

Edited August 13, 2013 by Spica

[espm400]

Personally, I go for a standard Munar injection, then mid-transfer adjust to polar orbit and circularize at ~50-100km (still don't know the optimal altitude).

[Trainsfan]

you'd want to be higher so it can scan more, but a polar orbit is the way to go. make sure you have plenty of batteries, and you don't need a full scan to know where the Kethane is.

[Johnno]

This topic was asked about/discussed just yesterday.

As for satellite design, I personally always add a RTG and a single battery, then you'll always have it functional in less parts than solar panels + batteries. Of course it depends how much the scanner uses in power nowdays, just adjust your design as necessary.

[annallia]

you'd want to be higher so it can scan more, but a polar orbit is the way to go. make sure you have plenty of batteries, and you don't need a full scan to know where the Kethane is.

Kethane scanner doesn't work that way. Doesn't matter if you are 50 meters off t he ground or 50 kilometers, it will only scan one hex at a time.

That said a 90 degree or so orbit (polar orbit) will be the fastest/most efficient as it uses the moons rotation to move your scanning area rather than you changing your orbit every few minutes. As to optimum altitude I don't know, that would depend on how fast the moon rotates. Faster it spins the lower the orbit you want, so long as you complete at least one full orbit before the moon rotates enough to make you move to the next line of hexes over you are ok.

Edited August 14, 2013 by annallia

[Respawn]

You want a formula to calculate absolute optimal altitude?

Number of seconds the mun take to rotate once

divided by:

number of hexes across the munar surface along the equator.

that gives you the number of sec you want your orbit to take. (one orbit pr hex)

call that number (T)

Look up the muns GM (newtons gravitational constant x mass of the mun)

and look up the radius of the mun, referred to in the formula as ®

calculate: cuberoot((T²xGM)/4pi²) - r = your optimal scanning altitude.

If that's inside the mun (ie "-something"), simply double (T) in your formula and you're all good.

this will simply make you complete the surface scan in 2 munar "days".

(if the number of hexes across the surface is an even number,

instead of doubling it, multiply it by 1,5 or 3 to avoid scanning the same lines twice)

Place your craft in a perfect circular polar orbit at your calculated altitude and you shouldn't miss a single hex.

happy counting..

[Frederf]

What kind of efficiency? Fuel? Game time? Real time?

[annallia]

What kind of efficiency? Fuel? Game time? Real time?

If that was aimed at me (since I am the only one who mentioned efficiency that I saw I assume it was) then all of the above. Since you won't have to constantly change your orbit it is more fuel efficient, more time efficient for you, and I guess there may be a faster way to do it in relation to game time but does that really matter? I would think that any benefit given by a different orbit would be negated by having to change your orbit every so often.

[Frederf]

Efficiency is mentioned in the thread title.

For complete coverage you absolutely need to to pass over the poles or at least within one hex radius. Thus the most efficient polar orbit entry is needed. For further efficiency one would capture into an elliptical orbit from minimum safe to max sensor range over a full set of latitudes (your Ap could be outside sensor range as long as you got from +90 to -90 latitude on one side of the body at least). But honestly fuel efficiency is not that critical. Slap an ion engine and a tiny Xe can on something and it can leave LKO and scan Mun, Minimus, Duna and Dres and have enough to come back.

Career mode may place some game-time restrictions. For example if life support ever gets modeled when not in focus it'll matter plenty. Some people just don't like time accelerating Kerbal years when it's only a probe.

Good time efficiency could involve a polar orbit that is reduced to equatorial gradually as the pole hexes fill and are no longer needed overflight.

I've also considered that your orbital period to Mun rotational period should avoid harmonization. Ideally your sensor craft would complete N polar scanning orbits as the Mun completed one rotation where N is the number of equatorial hexes. The idea is to have no duplicate scans and no gaps. I think this is physically impossible (negative orbit altitude) but 2, 3, 4, 5, etc. Mun rotation schemes are possible. The timing is frighteningly precise though.

[Kimberly]

It is probably more efficient to use a sub-polar orbit to scan most of the planet, and then switch to a true polar orbit to get the poles themselves.

[Zeroignite]

When it comes to resource scanning, on most worlds I don't even bother going above 30° inclination for the primary scan, since if the surface gravity is significant then I don't want to waste any fuel doing a plane-change on launch or landing anyway. I aim to put bases within 10° of the equator, and it's usually possible to find a combination of flat terrain and kethane in that band.