Is it really possible for Minmus to be made of ice?

[Streetwind]

If you bring a 2HOT thermometer to Minmus and take a surface reading, you will notice the temperature is always roughly around 0°C, maybe one or two degrees lower. One of the science messages (dunno if it's from the thermometer or from a different report) also states that it is "just cold enough for water to freeze".

So from an ingame canon standpoint, something keeps Minmus cool enough. What that something is - albedo, rotation, a giant fridge inside the core or other things entirely - that's for everyone themselves to imagine

[KerbMav]

Mostly albedo I think. And temperature readings in the game have been wonky and will stay wonky until a dev has enough spare time I think.

[boxman]

Assuming that Minmus has an icy surface, would it really be possible for that to exist?

Icy moons are common in the outer solar system where sunlight is weak, but in Kerbin orbit, direct sunight would melt any ice. Without much gravity or any atmospheric pressure, the water would instantly boil off and probably be lost into space.

Nope... If it is any substance we know of like water ice then it would not be possible at all because it would evaporate like you said. Minimum would also have a very high surface temperature in sunlit regions thanks to no atmosphere as well.

[boxman]

It is not entirely impossible.

Take Earth and Moon as an example: The moons average temperature is well below freezing (220K at the equator) while the Earth's is just above freezing (288K). The difference is a result of the effects of albedo, atmosphere and radioactivity.

On the Moon temperatures rise up to 390K, enough to biol water at normal pressure, but Minmus with its high albedo and relatively fast rotation my actually stay below freezing at all times.

The sunlit regions would still be hot on surface no matter what albedo it got. Also when there is no atmosphere the rotation rate matters very little since temperatures climb very quickly when shaded areas move into the sunlight.

The only place such a moon in real world could have ice is in the shaded areas like deep craters.

[lajoswinkler]

Assuming that Minmus has an icy surface, would it really be possible for that to exist?

Icy moons are common in the outer solar system where sunlight is weak, but in Kerbin orbit, direct sunight would melt any ice. Without much gravity or any atmospheric pressure, the water would instantly boil off and probably be lost into space.

No, it would not be possible.

If you had a chunk of ice the size of Minmus, its center would be liquid because of the pressure, and indeed, even pretty small bodies (accounting for the higher gravitational constant in KSP universe) would reach equilibrium and become rounded.

However, the ice would sublimate (no melting in vacuum) very fast and it would create a huge coma (way larger than Kerbin's SOI) around the body. It would essentially be a comet orbiting a planet with the planet inside the coma, a weird sight from far away. The tail would be still, pointing away from the star, the planet would essentially be in the middle of it, and the comet nucleus would orbit it.

No reasonable amount of albedo would save such body. It would gradually thaw into vacuum, probably shooting some geysers, launching ice chunks in the orbit. A temporary icy ring could be established if the decay is sufficiently powerful.

It could last for thousands of years. A blink of an eye in the geological timescale.

Any crust forming on the body would not stop it from thawing. Comets have nice, coal-black crusts and they decay.

Solid methane is even worse, and methane clathrates quickly decay when brought into vacuum. So that's absolutely impossible, too.

I always imagined Minmus just being a giant chunk of irradiated salt.

Me, too. Crushed greenish inorganic minerals. No ice at all.

[Brapness]

However, the ice would sublimate (no melting in vacuum) very fast and it would create a huge coma (way larger than Kerbin's SOI) around the body. It would essentially be a comet orbiting a planet with the planet inside the coma, a weird sight from far away. The tail would be still, pointing away from the star, the planet would essentially be in the middle of it, and the comet nucleus would orbit it.

That sounds unbelievably awesome. I hope that somewhere out in space this is actually happening. Wish I could see it...

[Kerba Fett]

It couldn't be made of ice. I've landed at the same spot next to my methane drill quite a few times. If it were ice my rocket engines would have caused some melting.

The huge flats are obviously from an advanced alien species strip mining there long before kerbals ever went to Minmus.

[Starwhip]

I think it's made of all the dead Kerbals that the space program killed before they found the big three, and they clumped them all far enough away as to not arouse suspicion. Until they started sending Jeb there...

[Skorpychan]

Best I've heard so far is that it's made of microcline. Which, as a DF player, I like. Because YOU HAVE STRUCK MICROCLINE is either the most annoying thing ever (YES I KNOW THE WHOLE MOUNTAIN'S MADE OF IT), or useful (Ooh, just what I need for my cyan megastructure).

Otherwise, some kind of syrupy dessert.

But, really, water ice is not green. It's white, or blue, or clear. And Minimus is a distinct greenish-blue. Water ice with impurities.