Are Breathable Desert Planets Unrealistic?

[Spacescifi]

I mean imagine a desert world with no ocean or even natural lakes or rivers on the surface... only ground water beneath as well underground rivers and subterranean lakes.

 

Could such a world even exist naturally?

 

I do not think so... unless some giant animal or a horde of smaller ones has a habit of boring through the crust.

Also, I suppose if a desert world has no water on the surface than it is so hot that the waters evaporate on the surface.

 

Meaning subterranean would be the only place to live.

 

So all in all... I guess I am implying that desert worlds like tantooine would be more hostile than they appear if designed as in the OP.

Edited November 25, 2022 by Spacescifi

[JoeSchmuckatelli]

Your inclination seems correct.

 

Need oceans and lots of microplants

 

[Spacescifi]

3 minutes ago, JoeSchmuckatelli said:

Your inclination seems correct.

 

Need oceans and lots of microplants

 

 

So Tantooine is either pure fiction or a world that was terraformed.

 

Knowing star wars I would not be surprised is if it was barren world with no atmosphere and they just terraformed it so that it did.

[JoeSchmuckatelli]

The legend has it that the Sand People are native, tho.

 

You need to go back to the Source Material: DUNE.

 

Dune had massive underground water reserves filled with life.  But reality; that place would not support complex life.  You have to have a LOT of the simple stuff first.

Edited November 25, 2022 by JoeSchmuckatelli

[JoeSchmuckatelli]

dune - How does Arrakis maintain a breathable atmosphere without vegetation? - Science Fiction & Fantasy Stack Exchange

[Scotius]

Reminder: Our sample size in the category "Habitable planets" = 1.

Let's not be hasty proclaiming that something is impossible.

[Spacescifi]

45 minutes ago, Scotius said:

Reminder: Our sample size in the category "Habitable planets" = 1.

Let's not be hasty proclaiming that something is impossible.

 

You have a point, I guess using Earth as a sample makes one use Earth as the standard... but seriously there are only so many ways you get enough oxygen to breath.

 

Earth has  so much ocean that even without plants I reckon/suppose the ocean will give up some oxygen atoms into the atmosphere anyway.

 

With just desert on the surface you won't even have that.

 

 

Edited November 25, 2022 by Spacescifi

[JoeSchmuckatelli]

43 minutes ago, Scotius said:

Reminder: Our sample size in the category "Habitable planets" = 1.

Let's not be hasty proclaiming that something is impossible.

I'd say, however, that we can put the likelihood at 'miniscule'.  Part of what supports your contention is that 'any' life found on a planet would make it, technically, 'habitable' or 'life-bearing'... but that's a far cry from hosting complex life.

i.e. Mars if we find bacteria or one of our ice moons; same.  Those would support Pan-Spermia as a theory... but not host humans.

So if you go to an entire 'desert world'... I think that it is a safe contention that absent a whole lot of water... there's no complex life.

[Scotius]

"The striking feature of Selaginella lepidophylla is its adaptation to conditions of prolonged drought in its natural environment. It deploys the physiological strategy of drying up and rolling inwards in the absence of water to form a ball, and can survive for up to several years, and lose up to 95% of its moisture content, without suffering damage."

As you can see, complex plant life doesn't require a whole lot of water. If Mars was a bit warmer, this sturdy plant could probably survive on what little moisture is available there. Life is an incredible process.

https://en.wikipedia.org/wiki/Selaginella_lepidophylla

Edited November 25, 2022 by Scotius

[RCgothic]

3 hours ago, Spacescifi said:

 

So Tantooine is either pure fiction or a world that was terraformed.

 

Knowing star wars I would not be surprised is if it was barren world with no atmosphere and they just terraformed it so that it did.

Tatooine was a verdant world laid waste by the Infinite Empire of the Rakata around 25200 BBY.

[magnemoe]

Single biome planets are an science fiction standard and I say mostly lazy writing.
Exceptions is  realistic ones water worlds or a water world with some small landmasses. 
And obviously dead worlds. 

Planet cities like coruscant is also impossible, not so much because of no oxygen cycle but that it would overheat, also an population of one trillion would just take up 12% more than humans on earth 

[Admiral Fluffy]

3 hours ago, RCgothic said:

Tatooine was a verdant world laid waste by the Infinite Empire of the Rakata around 25200 BBY.

"Tatooine was once a lush world that had large oceans and a world-spanning jungle inhabited by the native and technologically advanced Kumumgah. Against the elders' wishes they colonized nearby star systems and this drew the attention of the Rakata. In 25,793 BBY, the Rakatan Infinite Empire invaded the planet, conquered and enslaved its native inhabitants and then abducted many to their other conquered worlds. After a terrible plague weakened the Rakata, the Kumumgah eventually rebelled and managed to drive the Rakata off the planet. In response they subjected the planet to an orbital bombardment that "glassed" (that is, fused the silica in the soil into glass, which then broke up over time into sand) the planet and boiled its oceans away. It is possible that the Kumumgah's excessive production started this drastic climatic change before the Rakata arrived. Nonetheless this change split the indigenous Kumumgah into two races: the Ghorfas and the Jawas."

Quoted from wookipedia

[kerbiloid]

3 hours ago, Admiral Fluffy said:

an orbital bombardment that "glassed" (that is, fused the silica in the soil into glass, which then broke up over time into sand) the planet and boiled its oceans away.

1. Where has the ocean salt gone to? Why is the sand not too oversalty to farm?

2. Where has the ocean carbon dioxide gone to? Why is the planet not a supervenus?

10 hours ago, JoeSchmuckatelli said:

dune - How does Arrakis maintain a breathable atmosphere without vegetation? - Science Fiction & Fantasy Stack Exchange

Quote

But his inner digestive “factory,” with its enormous concentrations of aldehydes and acids, was a giant source of oxygen.

Acids don't provide free oxygen, they provide water.

Because they drop hydrogen.

They are something absolutely opposite to oxygen freeing.

Quote

Herbert never graduated from university. According to his son Brian, he wanted to study only what interested him and so did not complete the required curriculum.

Expectable.

Edited November 26, 2022 by kerbiloid

[Spacescifi]

45 minutes ago, kerbiloid said:

1. Where has the ocean salt gone to? Why is the sand not too oversalty to farm?

2. Where has the ocean carbon dioxide gone to? Why is the planet not a supervenus?

Acids don't provide free oxygen, they provide water.

Because they drop hydrogen.

They are something absolutely opposite to oxygen freeing.

Expectable.

 

You know the writers on the wiki page neither thought this through nor expect readers to.

 

Anymore than the 'turbolasers' which are'nt even lasers.

[KSK]

3 hours ago, kerbiloid said:

Acids don't provide free oxygen, they provide water.

Because they drop hydrogen.

They are something absolutely opposite to oxygen freeing.

Hmmm. A carboxylic acid (or an aldehyde for that matter) can be reduced to a primary alcohol plus water by adding hydrogen.

So, if the worms were capable of splitting water into hydrogen and oxygen (something equivalent to photosystem II in terrestrial plants) then I guess those aldehydes and acids could be a suitable hydrogen acceptor? Although that rather begs the question of where the all the water comes from.

Possibly? Maybe? Hey look over there - a squirrel!

But yeah,  I don’t think aldehydes and acids are likely to be a source of oxygen on their own.

[kerbiloid]

The problem is that the acids and aldehydes should be first produced from something.

[KSK]

More shower thoughts on Dune from a lapsed chemist.

1.  Water and carbon dioxide are both very stable molecules. As a rule of thumb, if either of them are one of the end products of a chemical reaction, then that reaction is likely to be favourable and go to completion.

2.   Aside. This is why hydrocarbons are so energy dense - they burn to two very stable molecules and release a shed load of energy in the process.

2.  It is demonstrably possible to biochemically split water into hydrogen and oxygen, else we wouldn’t be here discussing this.

3.  That being the case, I’d be reluctant to rule out the possibility of biochemically splitting carbon dioxide to carbon monoxide and oxygen [non-lapsed chemists feel free to chime in here].

4.   Carbon monoxide is poisonous to us but it’s also a versatile reactant for all kinds of chemical reactions, especially if you can also find some hydrogen from somewhere. Not necessarily a bad by-product to have around.

5.   End result. I can imagine some critter in the Arrakan ecosystem which is capable of directly recycling CO2 back to oxygen without requiring water as a primary electron acceptor (as per Terran photosynthesisers).

6.  Said critter probably wouldn’t be green (no chlorophyll, different wavelengths of light captured) so would be unremarked upon (compared to something green which would be very distinctive on a desert world.

 

[Superfluous J]

1. Discussing science.

2. Discussing Star Wars.

Pick one.

[KSK]

19 minutes ago, kerbiloid said:

The problem is that the acids and aldehydes should be first produced from something.

Probably from carbon dioxide and hydrogen. But yeah, this all gets messed up and back to front.

[kerbiloid]

50 minutes ago, Superfluous J said:

1. Discussing science.

2. Discussing Star Wars.

Pick one.

Dune.

[Nuke]

dune got away with it because the sandworms exhale oxygen, which it liberates from metal oxides in the sands. dune actually does have water its just walled off by the sandtrout.  dune does a really good job at explaining the ecology of arrakis. 

21 hours ago, JoeSchmuckatelli said:

Your inclination seems correct.

 

Need oceans and lots of microplants

 

need more datapoints. we only have one with reguards to life supporting planets. 

Edited November 26, 2022 by Nuke

[JoeSchmuckatelli]

27 minutes ago, Nuke said:

need more datapoints. we only have one with reguards to life supporting planets

I understand that hesitancy - but I think calling our planet a single date point is incorrect. 

This wet rock is more akin to a system of systems - and touring the system we find subsystems that are mutually hostile to one another, each hosting life.  (e.g. Sonora Desert and Atlantean volcanic vents) 

The one constant is water. 

So on balance, I find arguments suggesting that the next rock we find with life on it must be wet  far weightier than those like 'who knows maybe there are silica based life forms with radically different chemistry and they don't need water". 

Both could be correct - but the scale is tipped in a particular direction. 

[KSK]

Agreed.

Radically different chemistry - sure. Radically different chemistry of sufficient complexity to support life - that’s a quite a bit more difficult.

And whilst I’m reluctant to dismiss anything as outright impossible (because life is a tricksy thing and turns up in an incredible range of environments using an equally incredible range of nutrients and energy sources), as a species we’re pretty good at chemistry up to and including the more exotic ends of the Periodic Table.

So yeah, my money would be on carbon based watery alien life rather than rock beasties.

Edited November 26, 2022 by KSK

[Beamer]

Earth has technically been a desert world at several periods in its past (after the start of life).

There are a couple of definitions of a 'desert'. The biological one is typically centered around the hostility to life. Needless to say if you take this definition it would be unlikely as the definition itself is specifically centered around "hostility to life".

The geological one typically mentions the lack of precipitation caused by extreme heat or cold and/or the absence of abundant surface water. By this definition, Antarctica is a desert, and the entire Earth was a desert planet the few times in its past when it froze over completely. Of course life was quite simple during those times and it's possible biogenesis couldn't occur on such a world, but once life gets a foothold it is very good at hanging on.

We have a considerably large sample of planets and moons in our solar system. Virtually all of them are desert worlds. As far as we know only one of them carries life, I'd say it can't be a coincidence that this is also one of the very few rocky bodies that isn't a desert world. The only other ones I can think of are Venus and Titan. The idea that you need a world with water on it to have life isn't based on a sample of just 1, it is based on a single positive in a large sample of different worlds.

Of course the final word on whether there's microbial life elsewhere in the solar system isn't out yet, we still have quite some sub-surface work to do to be certain, but so far the results are pretty bleak. The universe at large doesn't seem to be very kind to life.

 

[Spacescifi]

13 minutes ago, Beamer said:

Earth has technically been a desert world at several periods in its past (after the start of life).

There are a couple of definitions of a 'desert'. The biological one is typically centered around the hostility to life. Needless to say if you take this definition it would be unlikely as the definition itself is specifically centered around "hostility to life".

The geological one typically mentions the lack of precipitation caused by extreme heat or cold and/or the absence of abundant surface water. By this definition, Antarctica is a desert, and the entire Earth was a desert planet the few times in its past when it froze over completely. Of course life was quite simple during those times and it's possible biogenesis couldn't occur on such a world, but once life gets a foothold it is very good at hanging on.

We have a considerably large sample of planets and moons in our solar system. Virtually all of them are desert worlds. As far as we know only one of them carries life, I'd say it can't be a coincidence that this is also one of the very few rocky bodies that isn't a desert world. The only other ones I can think of are Venus and Titan. The idea that you need a world with water on it to have life isn't based on a sample of just 1, it is based on a single positive in a large sample of different worlds.

Of course the final word on whether there's microbial life elsewhere in the solar system isn't out yet, we still have quite some sub-surface work to do to be certain, but so far the results are pretty bleak. The universe at large doesn't seem to be very kind to life.

 

 

What do you mean that Titan and venus are not desert worlds?

 

Do they have oceans of carbox dioxide?

 

I think titan has lots of ice but I think it's carbon dioxide ice or something not water.

Venus rains acid, so you may get pools of the stuff but it is so hot I doubt it would make any standing bodies of liquid last.

Jupiter, Saturn, and Uranus are rumored to have oceans of hydrogen which sounds cool... but trying to reach it sounds suicidal because of the 500 mph winds you would encounter on the way down and stormy atmosphere.