PDA

View Full Version : Desert Planets in sci-fi.



Click Ticker
2007-Oct-09, 03:32 PM
Not sure if this should be here or in Small Media - but I don't get it. Is this just one of those many areas in fiction where we are just supposed to suspend disbelief? Seems like science fiction is always coming up with a setting on a desert world. Without any plants - what's generating the oxygen? Or - since there is oxygen - why aren't the population centers near the plant life?

Or do I just ignore it and chalk it up to story telling?

Neverfly
2007-Oct-09, 03:47 PM
Not sure if this should be here or in Small Media - but I don't get it. Is this just one of those many areas in fiction where we are just supposed to suspend disbelief? Seems like science fiction is always coming up with a setting on a desert world. Without any plants - what's generating the oxygen? Or - since there is oxygen - why aren't the population centers near the plant life?

Or do I just ignore it and chalk it up to story telling?

Maybe some of the aliens breathe in CO2 and put out oxygen.

Do you know that according to Star Trek, Vulcans (like Spock) have green blood because of their close relation to plants? I can't remember exactly, but I think they supposedly had chlorophyll in their blood (suggesting that they could slightly photosynthesize...).

Swift
2007-Oct-09, 05:01 PM
It all depends on whether other planets' life behaves like ours. If it does, then you would need some quantity of water to create oxygen. But, I suspect, that might not be a lot of water. Most deserts on Earth support life and contain some small amounts of water. Particularly if there were not a lot of oxygen "sinks", either biological or mineralogical, you might not needs a lot of oxygen production to keep a reasonably high steady state concentration.

As far as Vulcans, I always heard that their blood was green because it used a copper-based equivalent of hemoglobin, as do some life forms on Earth (such as some mollusks) - more information here (http://www.daviddarling.info/encyclopedia/B/blood.html).

Tucson_Tim
2007-Oct-09, 05:05 PM
Do you know that according to Star Trek, Vulcans (like Spock) have green blood because of their close relation to plants? I can't remember exactly, but I think they supposedly had chlorophyll in their blood (suggesting that they could slightly photosynthesize...).

Isn't the green color of Vulcan blood because it is copper-based, compared to our iron-based blood?

Tucson_Tim
2007-Oct-09, 05:08 PM
In Dune, was it ever explained what the giant sand worms ate? Other than the occasional human or mobile spice factory.

tdvance
2007-Oct-09, 05:20 PM
Dune did seem to leave open the question of the great worms' energy source--sure they ate people, etc, but that doesn't seem enough to feed such energy expendature!

An alternate version of the first Dune story that Herbert never published had some info on underground caverns with mushroom-like life forms part of a tremendous ecology of which the sandworms were a part of. That still left open how the worms get energy--it would have to come either from the sun or the heat radiated by the planet's interior, and no mention was made that I remember of any means of converting one or the other into sandworm power.

For another desert planet: Tatooine, which is almost surely a copy of Dune (given that in the original draft Star Wars script, I recall reading somewhere, Princess Leia was a spice smuggler!)

tdvance
2007-Oct-09, 05:23 PM
Ok, I guess theoretically, it could use nuclear reactions to convert silicon in the sand into iron, but that would be quite a mechanism! Man would need to study that and figure out how to duplicate that! Cars running on sand....

Ilya
2007-Oct-09, 05:39 PM
In Dune, was it ever explained what the giant sand worms ate? Other than the occasional human or mobile spice factory.

I thought worms were land equivalent of whales -- they fed on vast amounts of microscopic organisms in the sand.

Of course that makes for a completely implausible energy budget, not to mention gives worms no reason to seek out and swallow vibration sources.

Tucson_Tim
2007-Oct-09, 05:42 PM
I thought worms were land equivalent of whales -- they fed on vast amounts of microscopic organisms in the sand.

Of course that makes for a completely implausible energy budget, not to mention gives worms no reason to seek out and swallow vibration sources.

I'm not terribly worried about it Ilya. Dune was a good book. It's a rare science fiction book that doesn't have a plot hole or two. Another question: Is it really possible for a giant worm to move at those incredible speeds thru sand?

Ronald Brak
2007-Oct-09, 06:10 PM
Sandworms are so long they make use of the temperature gradient between both ends. They are giant biological heat exchanges that. Usually they are inert and storing energy for vast periods of time, but ones in heat will seek each other out and fight to see which one gets to be male. And those stories about sandworms moving through sand are probably false. You try wriggling through sand and tell me how far you get. Instead it has been suggested that they move through tunnels in the spliff layer. The spliff are the enormous underground "trees" of Arrakis. But insted of making use of sunlight they are indirectly wind powered. They generate energy pnematically from the shifting weight of the dunes as they are constantly blown across the immense sand oceans of the planet. And how do the sandworms move anyway? Well they don't like to expose them to sunlight, so they're almost never seen, but from between their ring segments pop out millions of little feet that can run really fast.

eburacum45
2007-Oct-09, 07:26 PM
A planet could have very large deserts and still maintain an oxygen atmosphere. When Earth had all its continents jammed together the interior was very dry, as this wiki entry suggests.
http://en.wikipedia.org/wiki/Pangaea#Configuration_of_Pangaea

If a planet had much less water than Earth, so that the seas were all small inland seas, this still might be enough to support a population of photosynthetic water dwelling organisms, enough to produce a fairly oxygen rich atmosphere. In fact, once the crust was oxidised, the oxygen content could keep rising, as there would be no land based forests to combust and limt the oxygen levels.

Bur a completely dry planet- nope; I can't see that having an oxygen atmosphere.

Click Ticker
2007-Oct-09, 07:40 PM
A planet could have very large deserts and still maintain an oxygen atmosphere. When Earth had all its continents jammed together the interior was very dry, as this wiki entry suggests.
http://en.wikipedia.org/wiki/Pangaea#Configuration_of_Pangaea

If a planet had much less water than Earth, so that the seas were all small inland seas, this still might be enough to support a population of photosynthetic water dwelling organisms, enough to produce a fairly oxygen rich atmosphere. In fact, once the crust was oxidised, the oxygen content could keep rising, as there would be no land based forests to combust and limt the oxygen levels.

Bur a completely dry planet- nope; I can't see that having an oxygen atmosphere.

Good answer. Of course - bodies of water with heavy salt content would remove some of the motivation for settling near them (other then for shipping and other transportation conveniences. But I suppose any mammalian life forms would evolve near whatever fresh water sources are available, perhaps before the planet degenerated to a desert.

So to further this - what would prevent plant life from eventually adapting to land before humanoid life evolved? Assuming that the life on these desert worlds is native rather than colonists. Giving Star Trek some credit here - they did typically indicate that any humanoids encountered were colontists (at least on desert worlds).

JohnD
2007-Oct-09, 08:32 PM
Why do SF writers have to explain in detail 'how it works'? As long as the fact that it does work is extrapolated logically and entertainingly?

How many SF stories involve an FTL? That is never explained? (Apart from the Infinite Improbability Drive and the Bloater Drive)
Larry Niven has written about the difficulties that his JumpShift device caused him in describing a logical society - it would be just so damned useful!

Dune was (originally) not about sand worms, but about power politics and about the messiah cult.
The worms were incidental, 'macguffins' as Hitchcock called them, 'narrative devices' as described in any writing course.

Though it can be fun to tease out the mechanisms, just enjoy!

John

RalofTyr
2007-Oct-09, 09:13 PM
Deserts are the most common terrain on extra solar worlds, apart from gas giants.

Over 90% of the worlds in our solar system are desert. Mars, frozen desert. Venus, hot, hot desert. Io, volcanic desert. The Moon, airless desert.

Only for the last, 11% of Earth's existence, as there been land terrain other than desert.

eburacum45
2007-Oct-09, 09:45 PM
The problem with Dune was that it used ecology as a major plot device. I read it way back when I was an undergrad studying environmemtal science- the holes in the ecology seemed so blatant that I just wanted to rewrite it all the time.

Noclevername
2007-Oct-09, 09:52 PM
Sand plankton.

phaishazamkhan
2007-Oct-09, 11:28 PM
Why do SF writers have to explain in detail 'how it works'? As long as the fact that it does work is extrapolated logically and entertainingly?

Some people like hard science fiction with verifiable facts or at least plausible science.


How many SF stories involve an FTL? That is never explained?

Lots of them. FTL tends to be a plot device rather than a setting or simply something that keeps the story moving along. I'm sure there would be greater stories being told had they taken place aboard generation ships where the original crew won't see their destination yet their descendants will have the pleasure.


Dune was (originally) not about sand worms, but about power politics and about the messiah cult. The worms were incidental, 'macguffins' as Hitchcock called them, 'narrative devices' as described in any writing course.

Oho, so spice played no part in the politics and messiah cult? Spice mass becomes sand trout which become sand worms who continue the cycle.

In the case of George Lucas's films which inexorably are called science fiction rather than relegated to fantasy which happens to be set in outer space I believe that Hoth, Coruscant, Tattooine, Dagobah among others have a single environment for the sake of simplicity. Much the same way that the races in Star Trek are all one color with one language and one culture. Vulcans are exceptions which prove the rule and I do believe that Tuvok was a fluke.

I like authors to expand upon a concept, a setting or a plot device because there might be an interesting story within those topics. Doesn't mean that I don't know how to sit back and enjoy the show but I like to be challenged more than most folks.

Neverfly
2007-Oct-10, 12:53 AM
I had to rack my brains, but the reference to Vulcan blood came from the book "Spocks World" by Diane Duane.

Noclevername
2007-Oct-10, 01:01 AM
I'm sure there would be greater stories being told had they taken place aboard generation ships where the original crew won't see their destination yet their descendants will have the pleasure.



I don't know, I think the reason there aren't many such stories is that it's basically about a bunch of people sitting on a bus-- for their whole lives.

Tucson_Tim
2007-Oct-10, 01:04 AM
I don't know, I think the reason there aren't many such stories is that it's basically about a bunch of people sitting on a bus-- for their whole lives.

Deep Space 9.

Noclevername
2007-Oct-10, 01:07 AM
Deep Space 9.

At least on DS9, they could occasionally leave. On a generation ship, you're just stuck in the middle of nowhere. Not even waiting, except for that last generation who actually has something to wait for.

DS9's crew could also talk to other people outside their "world" without a decade-long time lag.

Tucson_Tim
2007-Oct-10, 01:08 AM
At least on DS9, they could occasionally leave. On a generation ship, you're just stuck in the middle of nowhere. Not even waiting, except for that last generation who actually has something to wait for.

DS9's crew could also talk to other people outside their "world" without a decade-long time lag.

So. It would be worse than DS9. That's pretty bad.

Noclevername
2007-Oct-10, 01:13 AM
So. It would be worse than DS9. That's pretty bad.

On the other hand, a ship full of scientists would have plenty of free time for education and research. A giant mobile University, with no funding issues.

Noclevername
2007-Oct-10, 01:15 AM
We've gotten away from "desert planets" a bit, haven't we?

Tucson_Tim
2007-Oct-10, 01:17 AM
We better get back on topic. Sorry Mr. Jenkins.

"Not one drop of rain . . ."

Noclevername
2007-Oct-10, 01:22 AM
http://en.wikipedia.org/wiki/Sandplankton

Told ya.

Noclevername
2007-Oct-10, 01:23 AM
Maybe SJ meant Dessert Planets. Mmmmm.... edible planet...

Noclevername
2007-Oct-10, 01:48 AM
From the Wikipedia Sandworm article:

The main diet of the worm seems to consist primarily of inorganic compounds of the Arrakeen soil, pre-spice mass and sandplankton tiny organisms that may even be immature sandtrout. They also seem to enjoy eating melange-harvesting equipment. The sandworm is equipped with a fearsome array of crystalline teeth (something not unheard of even in the worms of Earth), used primarily for rasping rocks and sand.

astromark
2007-Oct-10, 10:32 AM
Never mind the worms...you can get tablets for them. The deserts are common because the film set in the desert are cheaper than jungle locations... easy to fabricate a pile of sand and a blue screen. Sorry to spoil the fun.

folkhemmet
2007-Oct-10, 11:40 AM
One thing is for sure, the diversity of planetary systems and planets in the Universe is immense. We already know of one desert planet, Mars. What makes the sci-fi desert worlds interesting is that they have breathable, at least for humans, atmospheres. Without being constantly replenished, however, all of Earth's oxygen would have reacted with other substances long ago and we could not survive here without living in special biospheric domes. Actually, scientists involved in TPF and Darwin, two telescopic science missions supposedly capable of taking spectra of exoplanetary atmospheres, will be eagerly seeking planets with an strong O2 signiture because, as the theory goes, the presence of O2 in an atmosphere requires a replenishing source--which would probably be photosynthetic-based organisms.

So, I am not sure how a desert world with a O2 breathable atmosphere is possible without an O2 replenishment mechanism. And of course, lots of plants although doing the trick would sort of negate the label "desert world." I an interesting questions is this: Are there any other mechanisms capable of generating and maintaining O2 in a planetary atmosphere? How long would the O2 remain before reacting with other susbtances after the life died out?

Neverfly
2007-Oct-10, 11:54 AM
(snip)

So, I am not sure how a desert world with a O2 breathable atmosphere is possible without an O2 replenishment mechanism. And of course, lots of plants although doing the trick would sort of negate the label "desert world." I an interesting questions is this: Are there any other mechanisms capable of generating and maintaining O2 in a planetary atmosphere? How long would the O2 remain before reacting with other susbtances after the life died out?

What if we base an assumption that said desert world was not always a desert world but, rather at some point in its history, became one?
We cannot assume that only plants would make replenishment possible.

We are still working on explaining the real world we live in satisfactorily. If we are trying to explain science fiction, isn't it "acceptable" that there are unknown factors in sci fi just as there are in our real world that cause difficulty in explaining a given situation?

JohnD
2007-Oct-10, 12:25 PM
Some people like hard science fiction with verifiable facts or at least plausible science..
That's fine, just don't complain if the science isn't plausible.
As long as it fits the narrative.


Lots of them. FTL tends to be a plot device rather than a setting or simply something that keeps the story moving along.
Really? Lots of FTL drives have been explained?? Who has the Nobel Prize for Physics for an FTL drive then???
As I say, and FTL is just a narrative device. Apart from stories of the journey (Non-Stop?), other tales have to have it. "Sixty six years later, they arrived. Dead." The End. Doesn't make much of a tale, does it?


Oho, so spice played no part in the politics and messiah cult? Spice mass becomes sand trout which become sand worms who continue the cycle..
So we agree then - Dune IS about power politics and the messiah cult. Spice/worms etc were just narrative devices.

John

Click Ticker
2007-Oct-10, 01:27 PM
So, I am not sure how a desert world with a O2 breathable atmosphere is possible without an O2 replenishment mechanism. And of course, lots of plants although doing the trick would sort of negate the label "desert world." I an interesting questions is this: Are there any other mechanisms capable of generating and maintaining O2 in a planetary atmosphere? How long would the O2 remain before reacting with other susbtances after the life died out?

That's what I'm saying. The one possibility raised earlier is a vast ocean. The algae in the oceans replenishes the oxygen in the atmosphere.

Still doesn't make sense that colonists wouldn't settle by this ocean. Even if they couldn't drink it - they could use it for transport, and the sea life should be plentiful for dietary needs. The only thought that would overcome this would be that all the fresh water sources, even if they do require deep wells, are inland.

Click Ticker
2007-Oct-10, 01:33 PM
Why do SF writers have to explain in detail 'how it works'? As long as the fact that it does work is extrapolated logically and entertainingly?

They don't HAVE to. Some of the things in the stories are so obviously impossible that it's easy to dismiss them as plot devices. FTL is one of those things (at the same time - it adds to the enjoyment if the author put a little effort into how it might work). Other times - the ideas seem possible and part of the fun is to wonder if it could really work. For me, I'd like to know if such a setting were at all possible.

For instance, how long could a "Snowball Earth" maintain a breathable atmosphere?

Neverfly
2007-Oct-10, 01:39 PM
Bold mine:

They don't HAVE to. Some of the things in the stories are so obviously impossible that it's easy to dismiss them as plot devices. FTL is one of those things (at the same time - it adds to the enjoyment if the author put a little effort into how it might work). Other times - the ideas seem possible and part of the fun is to wonder if it could really work. For me, I'd like to know if such a setting were at all possible.

For instance, how long could a "Snowball Earth" maintain a breathable atmosphere?

I'm reminded of Sagans "Contact" and the work and lengths they went to to provide a realistic and believable, as well as researched FTL drive for the story. It was quite well done.

Noclevername
2007-Oct-10, 04:07 PM
The Alderson Drive from The Mote In God's Eye is an example of a well thought out and (within the framework of the fictional universe's laws of physics) scientifically plausible FTL. And yes, the fictional discoverers of this fictional FTL did recieve a fictional Nobel Prize for their fictional work.

Other scientifically plausible yet unproven FTL methods have been suggested by real world physicists, and subsequently adopted into fiction, such as a Kerr-Newman hypermass or a Morris-Thorne traversible wormhole.

Neverfly
2007-Oct-10, 04:10 PM
So that's the key then.

Hire the same guys that did FTL theorizing to do desert world ecology and Sci Fi will be set for at least a decade;)

eburacum45
2007-Oct-10, 04:40 PM
If a planet with a biosphere and a breathable atmosphere suddenly becomes a desert planet, gradually the oxygen in the atmosphere will migrate into the crust. Jon Clarke and I argued this out a few years back; it turns out he was right, and the crust will relatively rapidly (on a geological timescale) extract the oxygen from the atmopshere.
So if you fnd a desert planet with oxygen but no life, you can be pretty sure that the life disappeared a few million years ago tops.

Neverfly
2007-Oct-10, 04:44 PM
If a planet with a biosphere and a breathable atmosphere suddenly becomes a desert planet, gradually the oxygen in the atmosphere will migrate into the crust. Jon Clarke and I argued this out a few years back; it turns out he was right, and the crust will relatively rapidly (on a geological timescale) extract the oxygen from the atmopshere.
So if you fnd a desert planet with oxygen but no life, you can be pretty sure that the life disappeared a few million years ago tops.

Well, for Sci Fi, a few million years works doesn't it? I don't think the fictional characters care if the previous inhabitants vacated one hundred thousand years before as long as they can still breathe and don't need to worry about fighting the natives for water.

Delvo
2007-Oct-10, 05:19 PM
Exactly why would that happen?

Neverfly
2007-Oct-10, 05:21 PM
Why would what happen?

eburacum45
2007-Oct-10, 07:11 PM
I believe the question Delvo is asking is 'why would the previous inhabitants vacate the planet'?

It may be that the planet has been devastated by some astronomical disaster, such as a massive solar flare or nearby supernova, or even a gamma-ray burster jet. In this case the atmosphere would have been partially coverted to toxic nitrogen oxides; but these compounds aren't stable, so they'd get washed out of the atmosphere by rain over a few thousand years, leaving a sterilised planet.

The ozone layer would also have been destroyed by any nearby cataclysmic event, but would repair itself after hundreds of years. Perhaps some hardy organisms would survive, but all macroscopic biota could be destroyed by such an event.

Noclevername
2007-Oct-10, 07:16 PM
Perhaps an extremely omnivorous microbe wiped out all other life, then starved to death.

Delvo
2007-Oct-10, 07:47 PM
I meant why there is such certainty that oxygen would bind to crust minerals and be completely removed from the air. It couldn't build up significantly in the air until after it had saturated all of the available minerals that could absorb it and there was noplace else left for it to go. And when I learned soil chemistry in college there was nothing there to indicate any affinity for oxygen either, unless you plan on somehow getting it into positive radicals like nitrate and carbonate first.

Noclevername
2007-Oct-10, 07:50 PM
It couldn't build up significantly in the air until after it had saturated all of the available minerals that could absorb it and there was noplace else left for it to go.

Not quite true, with photosynthetic plants available the air can fill with free O2 much faster than the crust can absorb it.

Ronald Brak
2007-Oct-10, 08:13 PM
Maybe the sands of the planet Arrakis are filled with tiny photosynthetic organisms made of diamond. When they are buried deep in the sands they trap the trace amounts of water vapour that leak from the oceans of water that have sunk deep into the cooling crust that is hundreds of kilometers thick. When near the surace they use Photosystem I to create energy without water and fix carbon from the atmosphere leaving oxygen behind and digest particals of dust for the elements they need. Shield volcanoes over hotspots still add a small amount of carbon to the atmosphere each year and material is slowly circulated between the crust and mantle as the weight of material ejected by shield volcanoes causes the crust to sink into the mantle where it melts.

eburacum45
2007-Oct-11, 01:44 AM
The surface of the crust on Earth is nicely oxidised, you are correct. But new crust is being brought to the surface all the time, by geological processes; and that crust is less rich in oxygen. Jon supplied some figures to show that this slow turnover of the crust would extract almost all the oxygen from the air in a few million years; Wikipedia agrees.
http://en.wikipedia.org/wiki/Earth's_atmosphere#Evolution_on_Earth

Oxygen would vanish within a few million years due to chemical reactions

The crust has already sucked up massive amounts of biogenic oxygen; this slow turnover has extracted more than ten times the amount of oxygen currently in our atmosphere since the evolution of photosynthesis. This is one reason why the Earth had relatively low oxygen levels for a long time after the evolution of chlorophyll- the oxygen was being sucked greedily into the crust.

KaiYeves
2007-Oct-11, 01:47 AM
I'm reminded of Sagans "Contact" and the work and lengths they went to to provide a realistic and believable, as well as researched FTL drive for the story. It was quite well done.
Well, not all SF writers can be The Man.

Noclevername
2007-Oct-11, 03:22 AM
Forgot where I read it, but one sci-fi planet was described as being all shallow ocean, full of organic but toxic-to-Earthlife life, until a close passage of a rogue body a few million years ago churned up its interior, resulting in a sudden burst of continent-raising. End result, lifeless barren desert land just waiting for Terraforming, combined with small silty seas no one could swim in.

dtilque
2007-Oct-11, 05:31 AM
I thought Arakis had surface water until the evolution of the sandworm/sandtrout ecology.

Another desert planet with breathable atmosphere is Beta Colony from Bujold's Vorkosigan saga. No explanation there of how the atmosphere got that way.

BTW, you need more than just plants for an oxygen atmosphere. You also need a carbon sink where all the carbon from CO2 is sequestered. Calcium carbonate rocks and the bottom of the ocean are the two main carbon sinks on Earth. AIUI, you don't need life to make calcium carbonate rocks, but you do need water.

RalofTyr
2007-Oct-11, 06:30 AM
What about a "Near Desert World"? A world with say, half or less water. Sure, there are massive amounts of oxygen producing plants, near the waters, however, most of the world would look like the Saharas.

Sure, oxygen would go into the crust during usually earth like geologic activity, however, isn't water need for plate tectonics? No water means less oxygen would be absorbed into the crust.

also, what if an atmosphere was, like 70% oxygen? It would take a long, time to absorb that into the crust, etc.

Neverfly
2007-Oct-11, 06:42 AM
What about a "Near Desert World"? A world with say, half or less water. Sure, there are massive amounts of oxygen producing plants, near the waters, however, most of the world would look like the Saharas.

Sure, oxygen would go into the crust during usually earth like geologic activity, however, isn't water need for plate tectonics? No water means less oxygen would be absorbed into the crust.

also, what if an atmosphere was, like 70% oxygen? It would take a long, time to absorb that into the crust, etc.

You just described Australia.

Neverfly
2007-Oct-11, 06:43 AM
Yes, I know... I'm gonna get it:p

<covers his ears>

Nick Theodorakis
2007-Oct-11, 11:50 AM
... however, isn't water need for plate tectonics? ...

No.

Nick

jonfr
2007-Oct-11, 12:26 PM
If a planet with a biosphere and a breathable atmosphere suddenly becomes a desert planet, gradually the oxygen in the atmosphere will migrate into the crust. Jon Clarke and I argued this out a few years back; it turns out he was right, and the crust will relatively rapidly (on a geological timescale) extract the oxygen from the atmopshere.
So if you fnd a desert planet with oxygen but no life, you can be pretty sure that the life disappeared a few million years ago tops.

Is that what did happen to Mars ? It is a desert planet, by all definition. Even if it has a low air pressure.

eburacum45
2007-Oct-11, 12:28 PM
what if an atmosphere was, like 70% oxygen?
A planet with a very high O2 component in the atmosphere would support fire very well. If there is any surface vegetation, the plants would be constantly catchiing fire, unless they were extremely fireproof.

One type of planet which might have a very high O2 component is a waterworld; oxygen would form from photodissociation of water vapour, hydrogen would escape, but the oxygen could not reach the crust to be absorbed, because of a high-pressure ice layer on the seafloor.

The atmosphere would be breathable- just don't expect to smoke a cigarette without burning your lips.

eburacum45
2007-Oct-11, 12:33 PM
Is that what did happen to Mars ? It is a desert planet, by all definition. Even if it has a low air pressure.
There is no real evidence that Mars ever had a biosphere, or a substantial proportion of oxygen in its atmosphere. Perhaps Jon Clarke would know if there is any evidence available yet to rule out a past biosphere; there may not be.

But I think that most of the evidence suggests that Mars has had a low pressure environment for more than a billion years, at least.

Neverfly
2007-Oct-11, 02:39 PM
No.

Nick

Really?

Man my education must really be lacking...

I had thought oceans were an essential part of plate tectonics.

mugaliens
2007-Oct-11, 03:47 PM
Do you know that according to Star Trek, Vulcans (like Spock) have green blood because of their close relation to plants? I can't remember exactly, but I think they supposedly had chlorophyll in their blood (suggesting that they could slightly photosynthesize...).

I thought Bones said it was because it was based on copper, and not iron.

Neverfly
2007-Oct-11, 03:53 PM
I thought Bones said it was because it was based on copper, and not iron.

Yeah, I gave the reference where I had read the part about chlorophyl.
But it seems that particular author was off her rocker on this one. I googled it at that time and the cencesus is that it was copper.

Hey I dunno.
I'd ask Leonard but he might pop me in the nose.

Tucson_Tim
2007-Oct-11, 03:59 PM
I thought Bones said it was because it was based on copper, and not iron.

I mentioned that earlier in this thread. But there probably are good chemical reasons why copper wouldn't work.

Ronald Brak
2007-Oct-11, 03:59 PM
I'd ask Leonard but he might pop me in the nose.

Or pinch you on the neck.

Ronald Brak
2007-Oct-11, 04:03 PM
But there probably are good scientific reasons why copper wouldn't work.

It works on earth for a variety of critters. However it is not as an efficient oxygen carrier as hemoglobin. But I guess there would be ways to work around that.

Actually copper based blood is blue when oxygenated. But there are animals such as sea squirts with green vanadium based blood.

Ronald Brak
2007-Oct-11, 04:49 PM
One way to have a desert world with a long time permenant atmospere could be if the planet was tide locked with its closest star. There is an ice cap and open water on the dark side, but no permenant bodies of water on the sunlit side. However enough rain falls now and then to allow enough photosynthesis to maintain an oxygen atmosphere. Or if you want to get weirder, perhaps plants on the dark side split CO2 using kineticsynthesis powered by the planet's constant winds. If you'd like the planet to have a more earth like night and day then it could be tide locked to a brown dwarf which provides most of its heat while a distant but bright star provides most of its light.

Swift
2007-Oct-11, 04:51 PM
I mentioned that earlier in this thread. But there probably are good chemical reasons why copper wouldn't work.
I discussed it in Post # 3 (http://www.bautforum.com/1085348-post3.html), with references to Earth creatures with copper based blood and discussion about other possible metals.

Tucson_Tim
2007-Oct-11, 05:02 PM
I discussed it in Post # 3 (http://www.bautforum.com/1085348-post3.html), with references to Earth creatures with copper based blood and discussion about other possible metals.

Sorry. Didn't see that one. So, the TOS writers were pretty hip with that idea, huh?

Ronald Brak
2007-Oct-11, 05:12 PM
I didn't see it either. Sorry.

mugaliens
2007-Oct-11, 06:03 PM
Having lived in one desert for three years and another for a year, it's doable. Dig wells in dry riverbeds and you'll usually find water just a few feet down. Plants may not be plentiful but instead of trying to scavange the microfruit that does grow on them, you can scavange the animals that live on them. Food might be sparse but you really don't need 2,000 calories a day to survive indefinately. In many cultures 900 calories a day is enough for me and 600 for women. There's a lot of ways to obtain sustenance. Yes, it's a lot harder than visiting your local grocery store (which I did earlier today). But it's not as difficult as one might think.

Just a lot different than the farm life most of us are used to.

But in a desert with no water and no vegetation and no animals at all?

No way, unless there's some sort of sub-sand water-fixating mold on which humans can live...

mugaliens
2007-Oct-11, 06:06 PM
I mentioned that earlier in this thread. But there probably are good chemical reasons why copper wouldn't work.

Try Lobsters. Their blood is a light blue when oxygenated, which indicates copper.

RalofTyr
2007-Oct-11, 10:56 PM
A planet with a very high O2 component in the atmosphere would support fire very well. If there is any surface vegetation, the plants would be constantly catchiing fire, unless they were extremely fireproof.

Smokey the Bear would have had a hard time 320MYA.


One type of planet which might have a very high O2 component is a waterworld; oxygen would form from photodissociation of water vapour, hydrogen would escape, but the oxygen could not reach the crust to be absorbed, because of a high-pressure ice layer on the seafloor.

The atmosphere would be breathable- just don't expect to smoke a cigarette without burning your lips.

Which is very probable. Take Tau Ceti, it has ten times the cometry material our solar system has. So if there's a world orbiting that sun that can have liquid water, then it will have a lot of it and since the system is 10 billion years old, plate tectonics would have stopped as radiation decay inside the world is probably long over. Any continents would be worn down below sea level.

Also, a high oxygen level would create a Cambrian explosion of complex life, if it has life...

I would imagine a high O2 world to be breathable, but uncomfortable. Your eyes would water and burn from the O2.

Noclevername
2007-Oct-11, 11:35 PM
Actually copper based blood is blue when oxygenated. But there are animals such as sea squirts with green vanadium based blood.

Red blood is red because our blood plasma is transparent. Vulcans might have a green or yellow carrier fluid.

m1omg
2007-Oct-12, 01:23 PM
I think that microscopic algae photosynthesing in the rocks will do the trick, like on the planet Seat of Judgement in the Orions Arm.

m1omg
2007-Oct-12, 01:30 PM
I mentioned that earlier in this thread. But there probably are good chemical reasons why copper wouldn't work.

lol pseudo pessimism
crabs, for example, have copper based blood
And there is a benefit is that copper based blood is immune to carbon monoxide so this can be useful, for example, on a planet with a lot of fires

m1omg
2007-Oct-12, 01:31 PM
Smokey the Bear would have had a hard time 320MYA.



Which is very probable. Take Tau Ceti, it has ten times the cometry material our solar system has. So if there's a world orbiting that sun that can have liquid water, then it will have a lot of it and since the system is 10 billion years old, plate tectonics would have stopped as radiation decay inside the world is probably long over. Any continents would be worn down below sea level.

Also, a high oxygen level would create a Cambrian explosion of complex life, if it has life...

I would imagine a high O2 world to be breathable, but uncomfortable. Your eyes would water and burn from the O2.

Well there exists a hyperbaric oxygen therapy.

mugaliens
2007-Oct-12, 02:43 PM
lol pseudo pessimism
crabs, for example, have copper based blood
And there is a benefit is that copper based blood is immune to carbon monoxide so this can be useful, for example, on a planet with a lot of fires

Or during a young Earth where the CO2 level would have killed animals with iron-based blood.

Do you think perhaps that's why animals who's ancestors (crabs, particularly the horseshoe crab) which pre-date the explosion of life of on this planet have copper-based blood?

I wonder...

But I'm willing to bet trilobites had copper-based blood, as well.

Noclevername
2007-Oct-12, 04:29 PM
lol pseudo pessimism
crabs, for example, have copper based blood
And there is a benefit is that copper based blood is immune to carbon monoxide so this can be useful, for example, on a planet with a lot of fires

I think he meant for lifeforms of humanlike intelligence and sapience. Cuproglobin is less efficient at transporting oxygen. It works for arthropods, but large, complex brains need a lot of energy, and a lot of oxygen. So some way of boosting that efficience would be necessary. (Might explain why Vulcans are said to have a higher metabolism and blood pressure than humans; their cardiopulmonary system is built to work harder.)

eburacum45
2007-Oct-13, 08:13 AM
Smokey the Bear would have had a hard time 320MYA.


I think so too; however the forests of that time might have been particularly fire resistant, or fast growing. They were mostly horsetails and clubmosses if I recall correctly, so would have been reasonably different to today's trees. Perhaps they had a high moisture content or something.

Ronald Brak
2007-Oct-13, 08:35 AM
I think he meant for lifeforms of humanlike intelligence and sapience. Cuproglobin is less efficient at transporting oxygen. It works for arthropods, but large, complex brains need a lot of energy, and a lot of oxygen. So some way of boosting that efficience would be necessary. (Might explain why Vulcans are said to have a higher metabolism and blood pressure than humans; their cardiopulmonary system is built to work harder.)

As I mentioned before, there should be ways to work around it. And if you look at what an octopus can do it often doesn't appear sluggish at all and possesses intelligence comparable with many mammals. And if every creature on your planet has blood of similar efficiency then all you have to do is out smart them and out smart members of your own species and intelligence is pretty useful for out smarting, even if you are a slow thinker compared to us hemoglobin types.

Michael Noonan
2007-Oct-13, 08:49 AM
Well there exists a hyperbaric oxygen therapy.

Would there be anything in pressure differentials to the release of oxygen?

Say if a species had a lower oxygen releasing copper based blood system could travel to the depths of the ocean be a more efficient use of the carrier?

(Personally I am thinking along the lines of that clever Loch Ness Monster who knows when to show up and when not too. In brackets here because I am not being serious :lol: )