Whats the atmosphere of Pandora like?

[Lukas]

If its mentioned in the movie, then i missed it. Or is it described in the book? Whats the air the Na'vi breathe? How do you think they smell? I need a heads up, thanks.

[~ViperSB1~]

The Pandoran air has toxic levels of Methane, Chlorine, and Amonia and thats why the humans cant breathe it. But also has oxygen in it so I think thats what the Na'Vi actually use. I read somewhere that the atmosphere is like 20% thicker and the gravity is much weaker.

[Lukas]

The Pandoran air has toxic levels of Methane, Chlorine, and Amonia and thats why the humans cant breathe it. But also has oxygen in it so I think thats what the Na'Vi actually use. I read somewhere that the atmosphere is like 20% thicker and the gravity is much weaker.

I was thinking about that cause oxygen supports life. Maybe that combo of gasses made their skin blue, and that the reason why they have large cat-like noses. I noticed too the horses have gills, and if they use it like fishes do, then its to separate oxygen from other gasses. Thanks. Cameron really made a new world out there.

[NBrazil]

The Activist's Guide breaks it down...

From memory, Pandora has a Nitrogen/Oxygen atmosphere. The amount of oxygen is comparable to Earth's, but it also has 18% Carbon Dioxide and 5% Xenon with small amounts of Hydrogen Sulfide. Other sources (not this book) say trace amounts of Hydrogen Cyanide and Ammonia.

So that gives something like 20% oxygen, 18% Carbon Dioxide, 5% Xenon, and 1% others... implying about 66% nitrogen. The atmospheric pressure is 90% of Earth standard, but because of the density of Carbon Dioxide and very high density of Xenon, it is denser than Earth standard (which is why combined with the lower gravity, falling from height has a slow enough terminal velocity to use the plants to brake the fall).

Humans have a physiological response to high levels of Carbon Dioxide - while not particularly "toxic," it shuts down the breathing reflex. And in regard to smell, Hydrogen Sulfide is the "rotten egg" smell (it is also VERY toxic). Xenon is non-toxic, just dense. (And, of course, cyanide and ammonia are also poisonous.)

Dat's my analysis. (I was a chemistry nut in my youth.) Hope this helps.

[Lukas]

The Activist's Guide breaks it down...

From memory, Pandora has a Nitrogen/Oxygen atmosphere. The amount of oxygen is comparable to Earth's, but it also has 18% Carbon Dioxide and 5% Xenon with small amounts of Hydrogen Sulfide. Other sources (not this book) say trace amounts of Hydrogen Cyanide and Ammonia.

So that gives something like 20% oxygen, 18% Carbon Dioxide, 5% Xenon, and 1% others... implying about 66% nitrogen. The atmospheric pressure is 90% of Earth standard, but because of the density of Carbon Dioxide and very high density of Xenon, it is denser than Earth standard (which is why combined with the lower gravity, falling from height has a slow enough terminal velocity to use the plants to brake the fall).

Humans have a physiological response to high levels of Carbon Dioxide - while not particularly "toxic," it shuts down the breathing reflex. And in regard to smell, Hydrogen Sulfide is the "rotten egg" smell (it is also VERY toxic). Xenon is non-toxic, just dense. (And, of course, cyanide and ammonia are also poisonous.)

Dat's my analysis. (I was a chemistry nut in my youth.) Hope this helps.

Oh thanks, follow-up question, how about the decay process in that atmosphere? Like the dead Na'vi they just put it under a tree.

[NBrazil]

Oh thanks, follow-up question, how about the decay process in that atmosphere? Like the dead Na'vi they just put it under a tree.

Your guess is as good as mine - nuthin' 'bout dat in the book (and why should there be?).

Eh, I figure it is no different than on Earth in all respects, what happens here happens there (I assume scavengers, bacteria, etc.) Just an ecosystem doing its thing (I figure only higher organisms have the "interconnectedness," not single-celled ones - but that is just an opinion based on common sense.)

[sullyjakes14]

if so hydrogen sulfide smell like rotten egg smell .. so then can i just like fried my egg and let it rotten and smell it ?>? how bad can it be..come on now..is pandora we are talking about..and i would guess they must have alot of aerobacteria ..the bacteria that only live in extreme condition!

[RDAGoon]

On Earth you get lots of hydrogen sulfide gas where there are things like volcanic vents or in some cave systems.

[NBrazil]

From Wiki...

Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H2S is comparable with that of hydrogen cyanide. It forms a complex bond with iron in the mitochondrial cytochrome enzymes, thereby blocking oxygen from binding and stopping cellular respiration. Since hydrogen sulfide occurs naturally in the environment and the gut, enzymes exist in the body capable of detoxifying it by oxidation to (harmless) sulfate. Hence, low levels of sulfide may be tolerated indefinitely.

At some threshold level, the oxidative enzymes will be overwhelmed. This threshold level is believed to average around 300–350 ppm. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm.

So you see, it is very poisonous at a fraction of a percent value, and since it is a significant component of the atmosphere on Pandora, it would kill in minutes.

[NBrazil]

On topic, actually a more interesting question is why does the (fictional) Pandora have so much Carbon Dioxide?

While I'm no planetary scientist, I have a good layman's understanding of some of the principles as it relates to our solar system. For instance, it has been suggested that both Earth and Venus had similar amounts of primordial CO2, so why does Venus have a crushingly thick atmosphere of it while with Earth it is a minor component? The generally recognized answer is water. Venus is too hot for water to have ever existed in liquid form, whereas Earth isn't.

Water dissolves CO2 leading to the formation of carbonates. This process is both mineralogical and, later, organic. If all of the carbonates on Earth were broken down, we would have an atmosphere with as much of it as Venus has.

Now obviously Pandora has water too, yet it still has a very high CO2 content in the atmosphere. How can this be?

As I said, there is an organic fixation of CO2 on Earth. It is an essential part of marine biology (shells, for instance), and just as it took ages to create the oxygen atmosphere here (and I assume on Pandora), it took ages to remove the CO2. This didn't happen on Pandora. This may be "because" (remember, this is a fictional place) life took a different route.

Terran animals have bones with a mineral component of Calcium Phosphate, on Pandora the hard structures are based on carbon fiber substrates. Perhaps calcium carbonate shells never developed just like calcium phosphate bones didn't, leaving behind substantial CO2 (which, like Earth, is also replenished by Volcanic activity).

So, to get back to your initial inquiry in a round-about way, this means that water on Pandora would also be saturated with CO2 and hence acidic. Not seltzer water, as that takes extra pressure, but it would definitely have a tangy taste!

So now you have an idea of not only what the air smells like, but what the water tastes like.

All of this is pure speculation based on a layman's understanding of chemistry and astronomy - and put to the imagination of what it is like on this world. Kind of fun to look for consistency with real world science in regards to Pandora.

Cheers!