Duna's ice caps are too big

[Mitchz95]

Seriously, they must make up thirty percent of the planet's surface. Compared to the ice caps on Mars or even Kerbin, they are massively oversized.

Is there a reason for this? If not, I think they should be reduced in size at some point. Maybe not as small as Mars', but small enough that the planet looks "red with some white" from orbit rather than "red and white".

[AndrewBCrisp]

Maybe Duna was fortuitously placed to capture more water in its youth than Mars did?

Assuming Duna went through a similar history to Mars, then we'd see similar conditions that led to Mars losing its water and air. But if Duna had more water to begin with, then it would probably take longer for it to lose it. We're just at a point in Duna's history where it's still slowly losing water, and in another billion years, its icecaps will be no bigger than the Martian ones.

This has some interesting possibilities for surface conditions. Duna probably has most of its water not just in the icecaps but in permafrost around the planet. Maybe during local summer conditions warm enough that some of these areas (probably around the equator) thaw for a while, creating muddy or sludgy conditions, perhaps even spots of quicksand (quickdust?) that could trap unwary kerbonauts. Possibly a few light, sparse rains might dot the planet during the summers before the planet freezes up again. With each summer, some water escapes to the upper atmosphere, where photo-dissociation breaks it down. It could make for some interesting story and mission conditions - perhaps even an option for any weather modders out there.

Edited October 9, 2014 by AndrewBCrisp

[Tery215]

Because Duna is really cold, also theoretically an element that does that.

Sounds logical to me.

[boxman]

Seriously, they must make up thirty percent of the planet's surface. Compared to the ice caps on Mars or even Kerbin, they are massively oversized.

Is there a reason for this? If not, I think they should be reduced in size at some point. Maybe not as small as Mars', but small enough that the planet looks "red with some white" from orbit rather than "red and white".

I agree.. I have had the same issue since I started playing KSP back in .17 or .18.

Another thing I wish it had was some axial tilt and seasons so it actually changes depending on where it is in orbit. Would also be nice to have one of the poles be in dark side during winter. Another thing that would be nice is if the transition from desert to ice caps was more smooth and uneven.

Edited October 9, 2014 by boxman

[problemecium]

I agree with Andrew; Duna is cold, like Mars, but significantly "wetter", allowing more water (or perhaps another liquid) to freeze at high latitudes. Earth has looked like that a couple times actually during major ice ages (except not red of course).

[Rithsom]

It's not so much the size of the ice caps that annoy me, it's the transition from red to white. the red should slowly fade away the closer you get to the pole, not an abrupt line that separates the two.

[KerikBalm]

I suppose it would be cool if it goes from solid white to some red patches at the bottoms of drepressions, to white patches at the tops of high areas.

But as to the size: Its Duna, not Mars.

Will you complain that the atmosphere is too thick next (its over 10x thicker at at Duna's lowest point compared to Mar's lowest point)

[I_Killed_Jeb]

it looks nice, that's why

[Spatzimaus]

It's not so much the size of the ice caps that annoy me, it's the transition from red to white. the red should slowly fade away the closer you get to the pole, not an abrupt line that separates the two.

Yeah, that's not how ice caps work. It's not a smooth transition with the color gradually changing as you go. On a planet with a thick atmosphere you'll get enough weather to erode things to get the gradient you're thinking of, but one with a thin atmosphere just won't have the same effect. Any ice crystals that were away from the cap would be quickly covered in fine dust, melted, and eventually deposited back on the cap.

As to the rest, Duna is not Mars, Eve is not Venus, Jool's moons are not the same as Jupiter's, and so on. They were inspired by them and might have some similarities, but there are also some very noticeable differences, like the oceans on Eve and Laythe. So you just can't judge Duna's caps by Mars'.

[Commissioner Tadpole]

I think it is Duna's ridiculously huge ice caps that marks Duna an inspiration of Mars instead of just a clone. Seriously, it sounds silly, but it's what makes Duna be Duna, just like Spatzmiaus just said.

Edited October 9, 2014 by Commissioner Tadpole
Typos! Gotta catch 'em all!

[FenrirWolf]

If I recall correctly, Duna's design was pretty much lifted from a nifty looking randomly generated planet someone found in universe sandbox. Or was it space engine? I forget which.

[Liowen]

Duna ≠ Mars ......unless SQUAD changed its name in .25

[geb]

For comparison, here's Mars as shown by the Rosetta probe's OSIRIS camera during one of its flybys:

The ice caps are actually pretty big. It doesn't look too far different from Duna to my eye.

Also note that there's a big difference between the hemispheres. That's because Mars took an enormous whack with an impacting body at some point and the entire northern hemisphere is basically a crater. One entire hemisphere is at a higher average altitude than the other, and the different ground level atmospheric densities change what kind of weather they get. I think the difference is in how much CO2 falls as snow. Not 100% sure about that.

Edited October 9, 2014 by geb

[Sky_walker]

If KSP planets would make a logical sense - then perhaps this whole topic would make it too, but.... they don't, so.... it's kinda pointless thread, though mildly amusing.

[NovaSilisko]

Mars has undergone ice ages in the past which are theorized to have brought its ice caps down to very low latitudes. That was my main inspiration for Duna.

However, Mars' ice ages are caused by periods of high axial tilt, something KSP doesn't support.

FUN FACT TIME

The original idea I had for Duna, way before it was named such, back when it was the moon of a gas planet, and months before I joined squad, was an almost complete iceball world, with a thin ice-free band of mud at the equator - deep canyons of ice 10-50 km wide, and a few km deep, and at the bottom of them, the atmosphere would collect thickly enough to allow small bodies of water to form. This would've been boring as hell though, in hindsight, with the only interesting parts being at the equator with the rest being just frozen flat wasteland.

[Mitchz95]

Mars has undergone ice ages in the past which are theorized to have brought its ice caps down to very low latitudes. That was my main inspiration for Duna.

http://upload.wikimedia.org/wikipedia/commons/thumb/2/26/Mars_Ice_Age_PIA04933_modest.jpg/600px-Mars_Ice_Age_PIA04933_modest.jpg

However, Mars' ice ages are caused by periods of high axial tilt, something KSP doesn't support.

FUN FACT TIME

The original idea I had for Duna, way before it was named such, back when it was the moon of a gas planet, and months before I joined squad, was an almost complete iceball world, with a thin ice-free band of mud at the equator - deep canyons of ice 10-50 km wide, and a few km deep, and at the bottom of them, the atmosphere would collect thickly enough to allow small bodies of water to form. This would've been boring as hell though, in hindsight, with the only interesting parts being at the equator with the rest being just frozen flat wasteland.

Ah, I understand now. I still don't really love the look, but I guess that's what Texture Replacer is for.

I think that idea for a moon actually sounds interesting, as long as there's some varied terrain and an anomaly or two on the icy parts. Landing in that canyon with a spaceplane would be an awesome challenge. If more celestial bodies are ever added, it might be something worth revisiting.

[metaphor]

Duna also has an atmosphere that's about 30 times thicker than Mars's.

That ice canyon moon sounds awesome, especially if all the atmosphere collected in the canyons (with a very low scale height) so you could either land there with parachutes or land on the top propulsively.

[KerikBalm]

Also note that there's a big difference between the hemispheres. That's because Mars took an enormous whack with an impacting body at some point and the entire northern hemisphere is basically a crater. One entire hemisphere is at a higher average altitude than the other, and the different ground level atmospheric densities change what kind of weather they get. I think the difference is in how much CO2 falls as snow. Not 100% sure about that.

Thats 1 theory, for which there isn't all that much evidence.

The other theory is that its ancient seafloor.

And of course, there's the combined theory that the crater depression later filled with water.

Duna also has an atmosphere that's about 30 times thicker than Mars's.

That ice canyon moon sounds awesome, especially if all the atmosphere collected in the canyons (with a very low scale height) so you could either land there with parachutes or land on the top propulsively.

No, its not 30x thicker.

There is a difference between pressure and density.

Mar's atmospheric density gets over 1% of that on Earth, while the lowest spot on duna is less than 20% of kerbins atmosphere, as duna has no spot that is at exactly 0 altitutde

[smart013]

Mars has undergone ice ages in the past which are theorized to have brought its ice caps down to very low latitudes. That was my main inspiration for Duna.

Thats great! How often you get answers about a planet you are looking at directly from the creator? Never happens to me when i look at Jupiter, thats for sure

[worir4]

On those images you can see that the ice fades to sand and is not just a abrupt line separating them. I hope to see something like that in stock KSP.

@Nova, That original Duna you speak of sound really cool actually. Have you got any pictures of it?

[Geschosskopf]

Mars has undergone ice ages in the past which are theorized to have brought its ice caps down to very low latitudes. That was my main inspiration for Duna.

And here I'd been thinking all along that Duna was really modeled on the #13 pool ball

EDIT: This even allows for changing seasons

[NovaSilisko]

@Nova, That original Duna you speak of sound really cool actually. Have you got any pictures of it?

No, it never existed anywhere near KSP. I made a terrible rendition of it in Celestia a long time ago but I don't think I still have it.

[TimberWolffe]

I'm still confused at how polar ice caps are formed though because orbitally speaking they're the bits of the planet which are almost always in the sun

[lajoswinkler]

An old and quite valid complaint, but with modification - the sizes of the caps aren't the most important thing, their shapes are.

They are basically equal. It would be a lot better if there was some diversity, like if one cap was smaller and their borders were variable like real polar caps are on Earth and Mars. Valleys of red among the weird peninsulas of white.

[lajoswinkler]

Here's the diversity I was talking about.

Doesn't have to be exactly rugged like this, though.

Also this.

Some craters near the poles can have frozen lakes. All this combined makes an interesting terrain to wander around with a rover.