Frozen methane on Minmus?

[Jontu]

Minmus is too close to their sun (or whatever it\'s called - Kun?) to have methane ice.

[Ascensiam]

Clouds are yet to be added, how do you know Kerbin doesn\'t have an extremely carbon dense atmosphere, and anything outside it is frozen completely?

[UmbralRaptor]

eg: There\'s a working assumption that Kerbin has substantial amounts of sulfur hexafluoride in its atmosphere to explain the low scale height. As sulfur hexafluoride is a very powerful greenhouse gas, this could help explain things. Especially as Kerbol\'s mass is more consistant with a brown dwarf than a red one...

Alternatively, what\'s to keep Minmus from being moved once we have additional planets?

[thorfinn]

The only thing I don\'t like about the idea of strong greenhouse effect on Kerbin is unfortunately a kinda big one... every outer planet would by definition be a icy wasteland: in a game, we\'d like to have more variety.

[geb]

I prefer to think that Minmus is a huge corroded brass sphere, with asteroid debris piled up on it, but still with many patches of its surface poking through.

[closette]

It looks like frozen methane is HarvesteR\'s working hypothesis:

http://kerbalspaceprogram.com/forum/index.php?topic=13530.msg219016#msg219016

The sulphur hexafluoride component in Kerbin\'s atmosphere was my suggestion, based on the molecular weight derived from the scale height (5000 m) and the need for a greenhouse gas to keep its oceans and grass, e.g.

http://kerbalspaceprogram.com/forum/index.php?topic=2062.msg106155#msg106155

But there are quite a few inconsistencies with 'real world' expectations for all the objects in KSP.

The new KSP wiki gives Minmus\' density as 46.8 times that of water, somewhere between Kerbin\'s and the Mun\'s density:

http://kspwiki.nexisonline.net/wiki/Minmus

so it\'s certainly not methane all the way through, or 'cometary' material. It must have at least some of the super-dense (denser than Osmium) material that is a component of the Mun or Kerbin.

[Mr. Me]

(or whatever it\'s called - Kun?)

It\'s called Kerbol.

Kerbal+sol :

[duckunlimited2]

I believe the frozen methane on minmus isn\'t just composed of frozen methane but a combination of frozen methane and water called methane hydrate. Methane hydrate is methane molecules trapped in a cage of water molecules surrounding it. Now, methane hydrate can exist in a vacuum only if the temperature is -10 to -15 degrees Celsius. After doing a quick look on the forums, I found that the temperature of space outside kerbin\'s atmosphere is around 0 degrees Celsius, so I\'m guessing its the same on minmus. Now, that doesn\'t rule out that minmus can\'t be frozen. It can also be composed of other rock like substances on the surface with a methane hydrate layer underneath. Methane hydrate at 0 degrees Celsius forms if there is a pressure of around 50 earth atmospheres. Heavy rocks would do the trick and I would also imagine that it gets colder the further underground you go. The methane lakes are a bit tricky, since they exist on the surface. My theory is that some of the methane hydrate evaporates and forms a methane and/or water fog on the surface of the methane hydrate lakes. With cliffs as large as around 4000m (give or take a few thousand) surrounding the methane lakes, that fog ain\'t goin nowhere and can build pretty thick. once its thick enough it acts as an insulator blocking the heat that comes from Kerbol and cooling the surface of the methane lake to -10 to -15 degrees Celsius where the methane hydrate lakes can exist.

On a side note, it is said that methane hydrate can form in the outer reaches of the solar system. Being a small, icy body, I think minmus originated from the outer reaches of the Kerbol system that was slingshoted into the inner system where Kerbin picked it up.

There\'s my theory on how Minmus\' origins and how it can exist as it is now. Once we start adding clouds to the game, I would like to see fog on those methane lakes. YA HEAR THAT HARVESTER; WE BETTER PUT SOME FOG ON THOSE LAKES, OR ELSE IT GONE AND EVAPORATE ON US!

[closette]

Why methane hydrate in particular? Am I missing something? Solid methane + some impurities works fine for me.

I just did a quick (well not so quick) calculation of the effective temperature of a greenhouse-effect-free planet at the 0.09 A. U. distance from Kerbol, which I assumed had a red dwarf luminosity equal to that of Proxima Centauri (if anything it would be a little bit less, but Kerbol\'s stellar astrophysics doesn\'t make sense in any case).

I used a relation found here: http://en.wikipedia.org/wiki/Effective_temperature#Planet

... and got numbers between 100 K and 190 K, depending on surface albedo. Someone please check my calculations.

So you see Kerbin really needs that greenhouse effect! (One inconsistency - Kerbin\'s rotation should be tidally locked to its orbit around Kerbol, but either it is a new planet recently placed there by HarvesteR-God, or it has no tidal bulges).

It also took some digging but I found a phase diagram of pure methane, and sure enough it would be a solid, but probably slowly sublimating away on the sunny side of the planet. Not enough to give you the 50-bar pressure of a methane atmosphere though!

For other objects, perhaps a Venus or Titan analogue, I do like the idea of surface fog, which would make eyeballing a landing more interesting!

One could do this on the Mun already with dust clouds kicked up by rocket engines - '..picking up some dust' (Buzz Aldrin, Apollo 11 landing - http://www.hq.nasa.gov/alsj/a11/a11.landing.html

[closette]

The only thing I don\'t like about the idea of strong greenhouse effect on Kerbin is unfortunately a kinda big one... every outer planet would by definition be a icy wasteland: in a game, we\'d like to have more variety.

I know what you mean, thorfinn, but you just described Mars! More distant gas-baggiant planets could have large Titan-like moons with an atmosphere but that\'s a while off I bet.

An inner Venus-like planet with an atmosphere would be fun to try and get to and land on with parachutes, and I hope/presume something like that is being worked on...

[geb]

An inner Venus-like planet with an atmosphere would be fun to try and get to and land on with parachutes, and I hope/presume something like that is being worked on...

Venus would be very difficult to launch from if realistic atmospheric effects on the engines were modelled. Atmospheric pressure at the surface is so high that it chamber pressure in a rocket motor can\'t easilypush against it. Even a very powerful rocket loses so much thrust that it\'s not worth using.

[closette]

Good point. No spacecraft has ever lifted off another solar system body with an atmosphere (like a Mars sample return or manned mission would have to). Of course the devs can construct whatever conditions they want, such as an inner planet with a thinner atmosphere (and similar temperature to Kerbin\'s). That would make rocket launches easier but parachute-only or parachute-assisted landings harder - until we get airbags!

[thorfinn]

Good point. No spacecraft has ever lifted off another solar system body with an atmosphere (like a Mars sample return or manned mission would have to).

I think that the Kerbol system will let us experience many different regimes.

Actually, if it was me, I\'d make it a trinary or quaternary star system to make room for more combinations And maybe even have 'difficulty levels', by choice of which star to start from (each would have a life-supporting planet, with different parameters)

(The atmosphere of Mars is mostly negiglible in the return phase, by the way. Now, lifting off from Titan... )

[Jesus KerBeard]

I just figured the seas of Minmus had such high reflectivity that they never heated up enough to melt.

[Phoenix Aerospace]

Venus would be very difficult to launch from if realistic atmospheric effects on the engines were modelled. Atmospheric pressure at the surface is so high that it chamber pressure in a rocket motor can\'t easilypush against it. Even a very powerful rocket loses so much thrust that it\'s not worth using.

…Don\'t forget that on the surface, the temperature is hot enough to melt lead due to the greenhouse effect. However, one can bypass the problem entirely by building aerostatic habitats and outposts high in the atmosphere.

[tiger336]

it does not matter why it came from when i find out how i\'m towing it to deep space with jeb flying the darn thing!