Pressurized underground natural caverns?

[daniel l.]

Is it likely that worlds like Mercury or Mars might have sealed-up underground caverns that maintain an atmosphere comparable to an earlier stage in the planet's existence? If so, then given the lack of plate tectonics on such worlds, such a cave could be billions of years old, and could have enough pressure to sustain liquid water.

[kerbiloid]

Caves depth is very limited (iirc, 1.5 km for the Earth, and absolutely no caverns below 10 km, due to the yield strength).
And this is much less than atmosphere thickness, so atmosphere can be just a little denser there.

[Scotius]

Unless there is natural outgassing from the rocks, any gases would escape anyway - just slower Theoretically, on Mars we can maaaaayyyybbeeeeee find caves with higher concentrations of CO2 and methane. But it will be nothing like early atmosphere.

[magnemoe]

You can get over pressure gas pockets this is an danger with coal mining, don't think this is real cave sized. 
Natural gas tend to be under pressure but no caves. 

Caves tend to be created by running vater eroding on earth. Lava tubes is another way. 
On other planets you might have ice or other frozen stuff like co2 or methane melting or diffusing away leaving an cave. 

Now if a cave is blocked of air thigh and has an influx of gas you can get an over pressure.  
The problem is there the gas should come from, on earth we have natural gas who can do this, you might get something like this in the ice on ice moons but not realistic on geological dead bodies. 

[Nibb31]

Most caverns aren't sealed up. There will always be leakage from the surface, cracks, etc... Even without tectonics, there are still tidal forces and thermal variations that will cause cracks.

If you want to use caverns, you would need to seal them with either an in inflatable bladder or an applicable sealant.

[sevenperforce]

4 hours ago, Nibb31 said:

Most caverns aren't sealed up. There will always be leakage from the surface, cracks, etc... Even without tectonics, there are still tidal forces and thermal variations that will cause cracks.

If you want to use caverns, you would need to seal them with either an in inflatable bladder or an applicable sealant.

I think the question was more "could there be caves preserving ancient atmospheric conditions" rather than "could we use existing caves".

But yeah, unfortunately any ancient caverns would have long since equalized by now.

[kerbiloid]

39 minutes ago, sevenperforce said:

I think the question was more "could there be caves preserving ancient atmospheric conditions" rather than "could we use existing caves".

Or about an underground world with lakes and water droplets.

[sevenperforce]

27 minutes ago, kerbiloid said:

Or about an underground world with lakes and water droplets.

Sort of a "Journey to the Center of the Mars" notion.

[cubinator]

I don't think you could find a very large cave full of preserved ancient atmosphere, but frozen lava and ice on Mars might contain unchanged ancient air bubbles, and are a good place to look. I don't know if you could go back a billion years or four, but you could probably learn about at least the past hundred million.

Edited June 15, 2018 by cubinator

[NSEP]

I wouldn't want any Mars/Moon dust in my pressurised environment. Its fine, toxic, and has no wear, breathing that stuff is essentially like smoking, but instead of tar and char clogging your lungs, its nano-knives cutting your veins.

You probably won't be drowning, but definitely coughing up 'gruesome red fluids'. Oh, and that's just the lungs, imagine what this stuff can do to your 'greusome red fluids', food, clothing, spacesuits, et cetera, et cetera.

Im probably overexaggerating the power of space dust, but you get the idea. Space dust is not healthy. And im not living in an environment where im openly exposed to any of that.

[kerbiloid]

10 hours ago, NSEP said:

Space dust is not healthy.

And that's not just about Mars, but about almost any other celestial body except Earth.
That's all about any colonization. The dust is either abrasive, or toxic.

10 hours ago, NSEP said:

You probably won't be drowning, but definitely coughing up 'gruesome red fluids'. Oh, and that's just the lungs, imagine what this stuff can do to your 'greusome red fluids', food, clothing, spacesuits, et cetera, et cetera.

Oh, that's really not a problem.

Spoiler

 

[monophonic]

16 hours ago, cubinator said:

I don't think you could find a very large cave full of preserved ancient atmosphere, but frozen lava and ice on Mars might contain unchanged ancient air bubbles, and are a good place to look. I don't know if you could go back a billion years or four, but you could probably learn about at least the past hundred million.

+1 for adressing the actual question rather than some imagined far fetched idea of a question.

[FireKerb]

It's not space dust.

It's asbestos.