O2 source on a desert planet

Who says your life forms didn't evolve to live off of very minimal oxygen, thus allowing you to use underground moss and algae to provide for the planet's oxygen needs.

It's the visitors to your planet that would have to cope with less oxygen. Your natives would be just fine. You may have to research what kind of physiology would be needed for something to live on very minimal oxygen, but maybe those physical alterations would move your plot in some way?

No problem. Sometimes I 'm good at thinking outside-the-box. If you ever want to bounce more questions off of me, go right ahead.

TurkeyLurkey said:

I am writing a sci-fi that takes place on a desert planet. Water sources are only located in underground wells, and there is hardly any vegetation. So now I am realizing that I am missing a source for oxygen.

I am thinking about the idea of using underground vents or caves which would add some ambiance to a few scenes.

Any other suggestions?

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SiO[SUB]2[/SUB], aka silicon dioxide, aka sand.

TurkeyLurkey said:

I am writing a sci-fi that takes place on a desert planet. Water sources are only located in underground wells, and there is hardly any vegetation. So now I am realizing that I am missing a source for oxygen.

Any other suggestions?

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No. If you're trying to be physically scientific here (and by even mentioning oxygen, you pretty much need to be), you're in trouble without an oxygen-generating biota. The only reason free oxygen is present in the atmosphere of the earth is that it is continuously being replenished via photosynthesis by plants. Oxygen is extremely reactive, and will readily combine with any available cation. Iron rusts, copper corrodes, etc., for precisely this reason. No free oxygen exists on any of the other solar planets. If we ever detected a spectral signature of free oxygen in the atmosphere of an extra-solar planet, we could be 100% assured that some form of organic metabolism existed there.

Further, because of its reactivity, oxygen would very quickly disappear from any place where it wasn't biotically regenerated. Mars is covered with iron oxide, which is why it is rusty-looking. Somewhere in its distant past it had an oxygen chemistry going on, which is one of the major reasons scientists are looking for evidence of ancient organisms there. Something fed that oxygen into the early Mars atmosphere. Today, there is none. We saw wonderful evidence of that when one of the Mars rovers, early in their remarkable journeys, stumbled across a pristine iron-meteorite the size of a basketball, just sitting by itself on the surface:

http://marsrovers.nasa.gov/gallery/press/opportunity/20050119a/Sol339B_P2581_L456-B352R1_br.jpg

The damthing is just sitting there, with a little ferrous oxide dust from the surrounding surface deposits, probably deposited on it by wind, but otherwise is shiny metallic. No oxygen, no water, no rust. Clearly, when you get away from the Earth, Neil Young is wrong; rust does sleep.

Now, we have forms of life, perhaps representing vestiges of the earliest living things on planet Earth, that not only do not require oxygen, but find it toxic. These anaerobic bacteria metabolize sulfur in environments extremely hostile to oxygen-breathing organisms, places like deep-sea thermal vents and sulfurous hot-springs fed by volcanoes. But we humans would have a hell of a time (literally) in finding a safe way to interact face to face with beings living on brimstone.

caw

You could have some vegetation on the surface despite it being a desert. In real life there's shrubs, prickly pears, and cacti.

Blacbird has your answer - the planet USED to be oxygen-rich, but it isn't anymore, due, say, to an environmental disaster.

blacbird said:

No. If you're trying to be physically scientific here (and by even mentioning oxygen, you pretty much need to be), you're in trouble without an oxygen-generating biota. The only reason free oxygen is present in the atmosphere of the earth is that it is continuously being replenished via photosynthesis by plants. Oxygen is extremely reactive, and will readily combine with any available cation. Iron rusts, copper corrodes, etc., for precisely this reason. No free oxygen exists on any of the other solar planets. If we ever detected a spectral signature of free oxygen in the atmosphere of an extra-solar planet, we could be 100% assured that some form of organic metabolism existed there.

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Ganymede (Jupiter's largest moon) has an atmosphere of free oxygen. Venus' atmosphere is 97% CO[sub]2[/sub], so oxygen doesn't always form mineral compounds.

May I suggest that you look through Frank Herbert's Dune? That was a desert planet, and I guess Herbert just ignored the science needed for the production of oxygen. Might give you a path to pursue.

What about photosynthetic bacteria? Supposedly, that's how Earth got it's original source of oxygen. Perhaps it could be a hardy, drought resistant bacterium.

Just remember how large a planet is. It's not a state, a country, or even a continent. It's huge, about several million square miles (possibly even billion). See how diverse we are, and so far we've only inhabited ONE planet.

Your planet doesn't have to be all vegetation, or all barren wasteland, it can be varied. You could have several thousand square miles of bleak, sandy wasteland, and several thousand square miles of desert similar to Arizona. I understand you don't want full blown forests on your planet, but you can have some vegetation and still keep the feeling of bleakness. You don't have to stick to the stereotype of planets with one single landscape that goes on forever especially since you're apparently aiming for some level of realism.

Also, a place completely unsuitable for life generally won't sustain it, and often kill life that enters it. Does the surface have to be completely dry? Even deserts have some water. For example, the Sahara desert has the Nile River, and Arizona has the Colorado River. Lakes also form, though those are usually temporary and shallow. Only the Atacama desert, the driest desert in the world, has the Loa River, and it's about as bleak as it gets, being almost completely sterile of all life.

As an interesting side note, assuming the poles are roughly as desert as the rest of the planet, albeit slightly colder, the equator will logically be completely uninhabitable.

MargueriteMing said:

Ganymede (Jupiter's largest moon) has an atmosphere of free oxygen. Venus' atmosphere is 97% CO[sub]2[/sub], so oxygen doesn't always form mineral compounds.

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Ganymede has no substantial atmosphere whatever, as far as we know. Its gravity is far too weak to hold an oxygen atmosphere, or nitrogen or even carbon dioxide, which is heavier. And regards oxygen, I was specifically addressing free molecular oxygen, diatomic O2, not oxygen compounded with other elements as in the very stable compound CO2, which constitutes the major part of the atmospheres of both Venus and Mars. Point being, that the free oxygen readily combines with carbon, exactly in the way it does on earth when you burn any carbon-containing substance, like wood or paper or petroleum.

caw

A few thoughts.

Beings native to the planet live on CO2, not Oxygen and their skin photosynthesizes. like sentient plants or little green men.

The planets' "sand" is iron oxide, the planet consists mostly of it. When iron is heated it gets rid of its Oxygen. Volcanoes.

The landmass on the planet is a super continent that is converging. The large center area of the planet is desert, due to the rain shadow from the mountains that formed from the drift. The oxygen comes from the thin belts of life between the mountains and the oceans.

Use one of your big lies.

Significant underground vegetation that requires almost no light would work, but light is required for photosythesis as we know it.

Alternately, large-scale quartz deposits can be exposed to the surface and conduct light below ground where liquid water could be adequate to support vegetation. Extensive cave systems in areas of relative geologic stability would allow air conduits to the surface.

Consider that seasonal phytoplankton blooms contribute non-trivial amounts of oxygen to Earth's atmosphere. Subterranean oceans fed by quartz-conducted light could fill the same function on your own Arrakis without requiring subterranean forests.

An interesting plot point could be that the number of oxygen-consuming creatures on the planet far exceeds the oxygen-production capability of the planet's sparse biosphere.

I hope that's useful in some way, and that you'll forgive my speculation.