My story begins with a group of colonists on a ship when something happens (spoilers) and the colonists are forced to abandon ship and land on a nearby uncharted moon of a gas giant.

The good news: they have enough rations for a good long while and a couple of seeds and plants for farming. The moon has an atmosphere with oxygen, nitrogen (with a couple things I’ll get to later) and oceans worth of water. The landmasses on this moon are volcanic islands (think Hawaii or Iceland), meaning that the ground is fertile. Also the moon has a thriving biosphere, meaning plenty of plants and animals.

Now the bad news: the atmosphere has a lot of ammonia in it. I hesitate to give a concrete percentage (I’ve been burned and yelled at before) but I will say enough that a all of the local wild life has a good deal of ammonium in their tissue (like certain squids use for buoyancy) and the air isn’t breathable for terrestrial organisms (don’t take your helmet off).

Now I did do some research into ammonia before posting this so I know that ammonia is lighter than air (which gives me quite a few ideas for the flying animals on this moon) it is corrosive (which gives me a few ideas for how murphy’s law can run amuck) and that it reacts with moisture (such as the ocean and a persons lungs). So what this tells me is that my astronauts are stuck on a moon with air they can’t breathe, creatures they can’t eat and most probably water they can’t drink.

Now most of the is set up for a “science the s#%t out this” style story (like the Martian, The new Lost in Space and parts of the Expanse). The only problem is my expertise relates to biology and paleontology, not chemistry. So what I would like to know is how would someone with equipment to settle a new world deal with this? How would they filter the ammonia from the water and soil? Would it be possible to filter out the ammonium from the creatures to make something remotely edible? Can a group of people set to colonize this world?

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    $\begingroup$ Remember that ammonia is flammable, and if mixed in air at the right concentration is also explosive. An oxygen-ammonia-nitrogen atmosphere sounds quite unstable. $\endgroup$ Commented Dec 31, 2019 at 9:58
  • $\begingroup$ Alright did some research so tell me if I missed something. Ammonia is dangerous to Earthbase organisms at 300 parts per million (for reference CO two is 400 ppm). Ammonia is also flammable at 15%-28% of air volume, and since 400 ppm of CO2 doesn’t even Crack 1% I think the solution should be simple. And atmospheric composition of 7% ammonia should keep the moon toxic without it going up like a Roman candle. But I’m not a chemist, so what do you think? $\endgroup$ Commented Dec 31, 2019 at 17:50
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    $\begingroup$ I'm not a chemist either ;-) Your plan sounds reasonable enough to me, for whatever that's worth. $\endgroup$ Commented Dec 31, 2019 at 17:54
  • $\begingroup$ I only now realize that I probably need a name for this little moon. The best I could come up is Amun and Nushadir. Turns out that Ammonia got its name because Egyptians used ammonium chloride I.E. nushadir salt in ceremonies for the god Amun. Thoughts? $\endgroup$ Commented Jan 3, 2020 at 3:08

1 Answer 1


How would they filter the ammonia from water and soil
It would depend on the concentration of ammonia, other materials in the mix and the power available. Some form of molecular sieve to absorb the ammonia might work. Atmospheric gases would be pumped through a bed of media that absorbs ammonia, after a period of time the flow is cut off and the ammonia is driven off by heating the media and ventilating the bed with a small amount of ammonia free gas.

There are many methods available depending on contaminants and concentration of ammonia. Another approach would be freezing the incoming gas as ammonia freezes at a much higher temperature than nitrogen or oxygen.

All of these methods however would need a lot of power, spares, filters and replacement media etc etc and the source of those would be problematic. It would take a very long time to develop all of the industrial base required (or a very large craft).

Would the creatures be edible
Almost certainly not. Even on a very Earth like world the direction of Evolution is heavily influenced by random processes and the chance of biochemistry being the same are remote. There may be many similarities, chemicals repurposed and modified but chemistry is so vast that the possibilities are almost endless. On a world sporting huge quantities of ammonia the chemistry would be very different indeed with lots of amides, amines and heterocyclic nitrogen compounds in every imaginable form. With luck it might be mildly poisonous, if unlucky it could be deadly poisonous.

Can a group of people colonize this world
A group of people could colonize this world, but they need to bring a huge amount of stuff and they would probably also need resupply for a long time. I doubt that it would be successful on an unplanned “oops we found ourselves on a planet/moon with lots of ammonia what shall we do now” basis.


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