Pandoran atmosphere hypotheses.

[Spock]

The atmosphere of Pandora is made up of: Nitrogen, Oxygen, Carbon dioxide at 18%, Xenon at 5.5%, Methane, and Hydeogen sulfide. Can someone with enough experience put togethor a hypotheses of what would happen, specifically, to the human body when exposed to this atmosphere. Plus the atmosphere is also 20% more dense.

Another thing I want to ask is, if we were exposed to this atmosphere for say.... 15 seconds a day of breathing, would our bodies adapt?

[Prometheus]

The atmosphere of Pandora is made up of: Nitrogen, Oxygen, Carbon dioxide at 18%, Xenon at 5.5%, Methane, and Hydrogen sulfide. Can someone with enough experience put together a hypotheses of what would happen, specifically, to the human body when exposed to this atmosphere. Plus the atmosphere is also 20% more dense.

Another thing I want to ask is, if we were exposed to this atmosphere for say.... 15 seconds a day of breathing, would our bodies adapt?

You'd choke to death almost immediately...the high conc of CO2 would hit you like a runaway train let alone the H2S and HCN which is in the atmosphere. Only takes 1 part in 2 billion of H2S to start affecting you (bad smell), any higher than 1 part in 1 billion and it will kill you. HCN is even deadlier.

Actually, 18% CO2 would make the planet that hot, it'd be on its way to ending up like Venus. The surface temp would be close to the boiling point of water. The atmosphere would be like a dense, hot, foggy soup.

No amount of adaptation would allow you to live there.

[Mongo]

Actually, 18% CO2 would make the planet that hot, it'd be on its way to ending up like Venus. The surface temp would be close to the boiling point of water. The atmosphere would be like a dense, hot, foggy soup.

No amount of adaptation would allow you to live there.

That would depend on the insolation level as well. If Polyphemus (Pandora's gas giant primary) were at the equivalent of Mars's orbit in terms of insolation level (and don't forget that it probably eclipses Alpha Cen A for some part of each of Pandora's orbits about it), then the lower insolation level would presumably counteract the high greenhouse effect due to the CO2 (and CH4).

Indeed, to my knowledge the much lower solar luminosity in the Hadean/Archaean eons (70% of modern levels at 4.4 GA, rising to 80-85% at 2.5 GA) was more than counteracted by the very high CO2 and CH4 levels at the time, resulting in average temps in excess of 50 degrees C.

So if Polyphemus is sufficiently distant from Alpha Cen A, the average surface temps should be quite comparable to Earth's, if somewhat higher.

[Atan]

In the movie the humans where always wearing masks or holding their breath. I couldn't help but wonder, it's not just our breath that takes in oxygen, but our entire body. A lesson hard learned during one of the James Bond movies when a women died after being coated with enough paint that her body couldn't breath.

I would imagine just wearing a mask and having the rest of your body exposed to that environment for prolonged lengths of time would make you extremely sick.

[Pjalok'shi]

In the movie the humans where always wearing masks or holding their breath. I couldn't help but wonder, it's not just our breath that takes in oxygen, but our entire body. A lesson hard learned during one of the James Bond movies when a women died after being coated with enough paint that her body couldn't breath.

I would imagine just wearing a mask and having the rest of your body exposed to that environment for prolonged lengths of time would make you extremely sick.

I was thinking this too. The toxic air would get into your blood stream via you skin. Same way if you got into a bad tub full of alcohol. You would get drunk over time. The Mythbusters had an episode about his where they sat in a bath tub full of beer and their blood alcohol level slowly but steady when up and beer is only like 7% alcohol. This process is very slow, but with the concentrations being stated above. I would imagine it wouldn't take very long before you started to get sick from the aspiration through your skin. Maybe JC will come up with a Pandora rule to address this like "Humans are only slowed in the atmosphere for 30 at a time"

[Spock]

Thanks for your replies. These answers are very helpfull.

[Prometheus]

That would depend on the insolation level as well. If Polyphemus (Pandora's gas giant primary) were at the equivalent of Mars's orbit in terms of insolation level (and don't forget that it probably eclipses Alpha Cen A for some part of each of Pandora's orbits about it), then the lower insolation level would presumably counteract the high greenhouse effect due to the CO2 (and CH4).

Indeed, to my knowledge the much lower solar luminosity in the Hadean/Archaean eons (70% of modern levels at 4.4 GA, rising to 80-85% at 2.5 GA) was more than counteracted by the very high CO2 and CH4 levels at the time, resulting in average temps in excess of 50 degrees C.

So if Polyphemus is sufficiently distant from Alpha Cen A, the average surface temps should be quite comparable to Earth's, if somewhat higher.

Yes, but Alpha is 1.57 times more luminous than the Sun. Even at the distance of Mars, it would be receiving nearly as much light as we do from our Sun. Even when it first formed Alpha was brighter than the present Sun...not by much (about 5%), but it was brighter. The best distance from a star such as Alpha for an Earth like planet is around 1.34AU, just short of Mars' orbit about the Sun (1.52AU)

The effect of eclipsing caused by Polyphemus wouldn't counteract any warming effects generated by the CO2 enough to make a large difference. There is just too much CO2 in the atmosphere to counteract....that much CO2 would be the perfect blanket, it would trap L-IR that well. Not only that, Pandora would orbit the giant in fairly short time...probably a few days at the most, so for most of that time it would be out of the shadow of the giant planet. To be effective, it would have to linger in the shadow of the giant for quite some time (a week or more), and to be at the right distance to do that, the gravitational pull of the outer giant planet would probably disturb Pandora's orbit sufficiently enough to fling it out of the system.

In effect, there's too much CO2 in the given atmosphere of Pandora. Now, if JC had've said about 8000-10000ppm (not the 180000ppm quoted), that would be more like it. Even 20000ppm would be reasonable. We certainly couldn't breathe in an atmosphere like that, and it would keep the planet warm...4-10degrees warmer on average than we have at present...think Cambrian Period in Earth's history (CO2 = 7000ppm), the only difference being higher oxygen levels.

[Mongo]

Pandora would orbit the giant in fairly short time...probably a few days at the most, so for most of that time it would be out of the shadow of the giant planet. To be effective, it would have to linger in the shadow of the giant for quite some time (a week or more), and to be at the right distance to do that, the gravitational pull of the outer giant planet would probably disturb Pandora's orbit sufficiently enough to fling it out of the system.

I have to say that I don't follow you here. The percentage of its orbit that a moon could be in its primary's shadow increases with decreasing distance, with the limit being 50% of its orbit if the moon were skimming just above the primary's atmosphere. (Actually, the situation is more complex if the moon's rotation is tidally locked. The portion of the moon's surface that never sees the moon's primary would get the full stellar insolation, while the portion of the moon's surface that has the moon's primary directly overhead would get considerably lower direct insolation due to being blocked by its primary for some fraction of the time the star is above the local horizon. I imagine that there would be ferocious winds redistributing energy between the sub-primary and anti-primary hemispheres, with their strength depending on how much of the sky the moon's primary fills.)

From what I recall from the movie, Polyphemus takes up about 30 degrees in the sky, and hence (assuming that Alpha's apparent movement takes it directly behind the center of Polyphemus as viewed from Pandora) reduces Pandora's total globally-averaged insolation by 1/12th (plus whatever Polyphemus contributes in IR and reflected visible light).

[Human No More]

Carbon dioxide in that concentration would cause you to pass out very quickly, then eventually die of poisoning from it. The hydrogen sulphide would also cause rapid poisoning.

* 530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
* 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
*Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

So I'd guess the levels of H2S in the atmosphere are somewhere in the lower end of 530-1000

[Spock]

Carbon dioxide in that concentration would cause you to pass out very quickly, then eventually die of poisoning from it. The hydrogen sulphide would also cause rapid poisoning.

So I'd guess the levels of H2S in the atmosphere are somewhere in the lower end of 530-1000

Whoo, lets boogie. I love hearing this this kind of thing.