Space: Desert Planets
 

GURPS Space doesn't really seem to allow for desert planets as rolled up "by the rules". The planetary generation system was written according to cutting edge science when it was written in the mid-200x's, but science marches on.

Here's a reference ( http://arxiv.org/abs/1304.3714v3 ) that I admit I didn't read all that much because I'm not a scientist, but what I got out of it is that we can have our Tattoines and Arakkises!

My question is, should we still call these Whatever-size (Greenhouse), or do they get a new (Desert) tag?

Re: Space: Desert Planets
 

I rolled up a few "hot garden" planets when I was working on my own space opera setting, one of which I jokingly named Tatooine as it was in a binary system (the geek shall inherit the stars, after all). I think calling a planet that could nominally be called a Garden planet with a "Hot" Climate (a high blackbody temp and an average surface temperature at the high end of the human survival range) can pretty much be called a "Desert" planet without too many problems.

Re: Space: Desert Planets
 

A planet being on the inner edge of the life zone isn't going to make it a desert planet, it's going to make it a hot one. In fact this is likely to lead to more super storms which means more rain, leading to less deserts then normal

Re: Space: Desert Planets
 

Here's my take on Desert planets.

You have to make some concessions in GURPS space to have a breathable atmosphere, presuming that's what you want.

Re: Space: Desert Planets
 

The problem with desert planets is mostly that the only means we know of for creating or sustaining a breathable atmosphere involves quite substantial amounts of water. Other than that, dry planets are perfectly possible, though they'd probably resemble Mars more than Arrakis.

Re: Space: Desert Planets
 

You overlooked the way to get a natural garden-world's hydrosphere lower than 45%. Tide lock it.

Re: Space: Desert Planets
 

Right, so, okay, my intention here: This is for a GURPS Space Opera... concept that I'm working on, and the idea is that it emulates the sort of Captain-and-Crew sci-f that tends to populate TV. One element of that is that you have many "single biome" planets, and that those biomes imitate what we expect. You are completely correct that in a strict definition of "desert," we mean "lacking water," but to most people, when you say "Desert," they picture a hot, sweltering landscape of sand and stone. When you load up a video game or turn on a TV show and it features a planet with such a landscape, people would cal it "a desert planet."

Hence why my desert planet is hot. It's not because that's the only way to get a world with low hydrography, but because I'm trying to show how to emulate the sort of planets I'm talking about that you might find in such sci-fi. That means the two defining characteristics for the average space opera fan of a "desert planet" would be "It's hot" and "It's dry"

(The link I gave, of course, lacked that context).

The purpose of my GURPS Space examples are to show how you might go about creating such a world "by the book," following the GURPS Space rules. On the softer-science side, I have no problem with someone simply declaring a world a desert world, and on the harder science side, I don't have a problem with someone coming up with their own planet-generation system. The purpose of that side-bar is primarily to discuss such a world in the context of the GURPS rules.

I'm completely open to the idea of expanding a new section that details the scientific mechanics of other ways to plausibly have a world (I want this particular site to cater to a sliding scale of scientific accuracy), but I honestly lack the scientific acumen to expand such a section on my other biome-worlds.

EDIT: And I believe my side-bar actually accounts for all of the stuff you mention regarding the lack of moisture, at least inasmuch as the climate rules of GURPS space covers that, which is why the black-body temperature is so high. The lower hydrography does impact those numbers, IIRC, though it's been some months since I looked at the numbers. Though, as I said, that sidebar is about staying in the lines painted by GURPS Space, rather than necessarily digging into the actual mechanics of real planets.

Re: Space: Desert Planets
 

The thread itself can be about those things. I was just offering the context for my particular article. Someone is asking about desert planets, I'm showing some of the work I've done on it. It doesn't have to be exhaustive or all-encompassing. Many of the points you made are valid. But you also made them in regards to my specific article, so I was answering your points in regards to my specific article.

For the purposes of the OP and this thread, I suspect your points are perfectly valid, and a nice contribution in addition to and in parallel with my contribution.

Re: Space: Desert Planets
 

Deserts are defined as getting fewer than 10 inches of rainfall a year, I believe. I feel people here define it as hot and dry.
The problem is that truly dry regions on earth like the heart of the Atacama, where rain hasn't fallen for centuries, there is zero life, not even lichen or native bacteria.
If you want a true desert planet with water based life, then you need to throw realism out the window entirely.

Re: Space: Desert Planets
 

Can you get a water cycle with something other than oceans and rain? A shifting fog, perhaps?