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Humans find themselves on a really hard to survive planet. I have a good idea on how I'd like it to be, but no clue on how that could be possible.

  • Atmosphere is breathable and temperatures make it possible to live there without the need of sophisticated technology.
  • There are no masses of water (nor other liquids). There might be puddles or really small lakes, but no big bodies of water.
  • There are many vapor geysers. Whatever gases emerge from this geysers, should find a way to go back there. Otherwise I understand it would mean that at some point this planet will stop expelling such gases.

How could such planet exist?

I find myself hard to put all this together (specially the last two). It's my understanding that if a lot of gas is continually expelled, for it to go back underground it should condense, rain and filter underground. That would easily imply the apparition of the seas I want to avoid.

I'm completely open to any size and orbit of the planet to make the three points happen.

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    $\begingroup$ Unless there is sufficient water, it doesn't matter if the atmosphere is breatheable. You simply cannot bring in enough water to colonise the entire planet, unless you hit it with an ice asteroid or something. We have oxygen because plants convert $CO_2$ for us, and those need water to function. You would need to posit some other alien mechanism to free up oxygen, but that leads to a xenobiology question, $\endgroup$ – nzaman Oct 29 '18 at 14:21
  • $\begingroup$ I would like to handle the water needed for life on another question, since I understand that atmosphera will have Oxygen and Hydrogen. I'm ok with some sort of aparatus to synthetize water from there. Anyway, the vapors could be simply water vapor, and humans could be able to get water from there, but I did not want to make it a must-be. $\endgroup$ – Masclins Oct 29 '18 at 14:24
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    $\begingroup$ Of possible interest to you worldbuilding.stackexchange.com/q/51272 $\endgroup$ – Ash Oct 29 '18 at 14:44
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    $\begingroup$ Free hydrogen would escape into space unless it was trapped in the gravity well of a gas giant or larger. $\endgroup$ – nzaman Oct 29 '18 at 17:39
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What you need is a planet that has a deep coarse regolith so that rain water can't stay on the surface then the geysers are just a matter of hot rock under the regolith converting the water that percolates down back into vapour. You can have a surprisingly large volume of water without anything showing on the surface this way. If you also have single-celled photosynthesisers that live on the surface and intercept a little water and sunlight then the atmosphere can be oxygenated as well.

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I'm pretty sure my guess doesn't fit your desired world.
What if the vapor geysir don't just shoot any type of gas, but water?
The world has a water cycle in which the water doesn't really stay above surface, but under: Water gets heated up by earth core and shoots through the geysirs into freedom. And then it rains back to the underground pool.
It seems that there is no really reachable water for the survivors.
I hope this helps :)

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  • $\begingroup$ This fulfills my expectations, but I wonder how is it possible that water doesn't create lakes and rivers when it rains. $\endgroup$ – Masclins Oct 29 '18 at 14:57
  • $\begingroup$ @Masclins it rains back in the underground holes. or it rains down and flows in the underground pool. It could sink through the surface or flow in rivers there. You can do whatever you think is right $\endgroup$ – user55267 Oct 29 '18 at 14:58
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The entire surface of the planet must be made of a very porous substance. This way, when it rains, the rain immediately flows down into the earth's mantle, where it is re-heated and re-shot back into the atmosphere.

Take for example, the sidewalks at Yellowstone, they are designed so that water flows through them and does not sit.

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    $\begingroup$ A sponge planet, in short :) With a huge moon for the squirt action. $\endgroup$ – Maarten Bodewes Oct 29 '18 at 22:39
  • $\begingroup$ Lol, id say thats an extreme example. 😂 $\endgroup$ – Alice Oct 30 '18 at 14:53

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