Space: Desert Planets

[Nymdok]

Originally Posted by whswhs

How did we get from "less than 250 mm" to "zero"?

I think this is at the crux of it. A really small amount of rain with a little 'life finds a way' optimism could lead to something that is at least 'plausible' depending on your tastes.

Arrakis (didnt read the books, just saw the movies) DID have water, just not enough to qualify as 'alot' on a global scale. But it WAS enough to keep the fremen alive and even at the end of the movie have a nice rainstorm.

One of the areas you might explore for 'wiggle room' in building a desert planet is abandon the idea of a completely oceanless world. If venus, for example, DID have (signifigant) water (and of course a different atmosphere), the oceans would be shallow and I would think more subject to larger temperature swings and maybe even enhanced cloud production that could carry enough rain over a desert landscape to still qualify as a desert AND support life.

So in your pursuit of a Desert world, consider a spectrum of systems from the Atacama to the Sonoran and I think you might be suprised what you could come up with. Dont think of JUST the barren arrakin landscape, but think of one that has that as a large component but maybe also fragile arid ice caps, thin cranky oceans, and in spots even cactus type plants and tumbleweeds with Gorn like creatures existing quite comfortably.

Now Anthony IS right about Water going hand in hand with what we consider liveable mostly due to the large amounts of Oxygen needed to make water, but its not absolutely the case. Consider again, Venus, which technically has more oxygen (in the form of CO2) in its atmosphere than Earth does! (About 100 times as much!) And yet, due to other reasons, there is little water.

Nymdok

p.s. Please note that I dont have the planet building rules from GURPS Im just trying to throw out ideas.
p.p.s. Please also note that Im a firm believer that with enough explanation, almost anything can be plausible.