Duna's ice caps are too big

[Whirligig Girl]

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.

No. Space Engine is the only which creates procedural worlds, Universe Sandbox doesn't. (Well, Ubox2 does) However, Kerbin's design was lifted directly from LibNoise. They didn't even change the generation seed. They just flipped it backwards!

[Alshain]

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

They receive the least amount of direct sunlight. The angle that the sunlight approaches to the poles causes more of it to refract off the atmosphere and less to reach the surface. Tangent rays of light may light up the sky but they never reach the surface. That is my understanding anyway, I'm no expert. There is probably someone that can better explain it than me.

EDIT: Here is a picture I just googled.

Edited November 5, 2014 by Alshain

[Red Iron Crown]

The sun's light must pass through more atmosphere to reach the surface at the poles, so more energy is lost heating the atmo instead of heating the surface. Imagine a cloudless summer day, does the sunlight feel as warm early in the morning or late in the afternoon as at high noon?

The poles are also a tiny bit further from the sun, but that's not as significant.

[Bill Phil]

Mars can have an equatorial region that's actually fairly small that is the only place without ice. So they're too small, really.

Mars has an incredible axial tilt, and it's not stabilized by a moon like Earth's.

[NERVAfan]

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

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

Yeah, it's not really that much thicker, though it looks like it if you compare the nominal values. But the nominal value for Mars is at a "datum" altitude and much of the planet is much lower than that.

Mars datum altitude pressure is about 0.006 atm, but the highest pressure (in Hellas Basin) is around 0.016 atm, whereas Duna's nominal pressure at 0 altitude is 0.20 atm - but, as KerikBalm says, it doesn't quite get down to 0, so I'm not sure what the actual max is.

In any case the difference is somewhat more than a factor of 10, but definitely not 30.

[Kerbonautics]

It is also impossible to drive on Duna:mad:

[sal_vager]

How so Kerbonautics ?

[CaptainTurbomuffin]

it's easier to land there.