So, I've got a planet with this atmosphere.

The composition is:

  • 60% NO
  • 20% NO2
  • 10% N2O
  • 5% N2
  • 5% O2
  • traces of CO, CO2.

The surface pressure is 0.7 atm, temperatures range from -30 to +30 degrees Celsius. Temperature and pressure do not bring up any problems, but the composition of the atmosphere surely does.

If you leave the spaceship unprotected, you will probably suffocate while literally laughing to death: NO2 is poisonous but N2O is a gas with euphoric effects that is called "laughing gas".

Now, the astronauts want to design a device which separates the various oxides of nitrogen into N2 and O2 and mixes them at a ratio of 8:2 to create "normal" air.

My questions are:

  • How would such a device work? I want one big version for spaceships and habitats and a smaller "breathing mask" which astronauts wear when exiting their habitats.
  • Does a person who wants to step onto the surface of the planet need any equipment other than the special breathing mask?
  • $\begingroup$ Would a catalytic converter help, the ones in cars split Nitrus Oxides into N2 and O2, The process is exothermic and most effective when hot so the air filter is also a power source. $\endgroup$ Jun 6, 2016 at 17:41
  • $\begingroup$ I mentioned this in your other thread...but an atmosphere that is 95% oxidizers means 'being on fire' is a serious threat at all times. And absolutely everything that is ever exposed to that atmosphere has to be made of something that will not react with Oxygen. $\endgroup$ Jun 6, 2016 at 20:46
  • $\begingroup$ Yea, the atmosphere could not exist as the components react with each other far too readily. $\endgroup$
    – JDługosz
    Jun 7, 2016 at 6:59

2 Answers 2


Isn't NO highly reactive with oxygen? NO reacts with oxygen to form NO2. No2 is highly reactive, so your atmosphere is unstable, isn't it? Do you have some mechanism for replenishing the levels of nitrogen compounds?

NO2 is highly acidic, yes? Seems like your astronauts would need some acid proof suits.

They might could freeze the atmosphere and separate out the oxygen!


To add some details:

The NO will combine with the O2 to give NO2. NO2 has a tendency to combine with itself to give N2O4. Both NO2 and N2O4 will combine with any hydrogen around (including water) to give nitric acid, HNO3, which will corrode most things. Breathing this atmosphere with your damp lungs coated with nitric acid will hurt so much you won't laugh while you're dying.

Is there something really, really desirable on this planet? It looks like a great place to leave alone.

  • $\begingroup$ The main point of the novel will be the exploration of the planet. Maybe there is gold or a huge amount of radioactive ores? $\endgroup$ Jul 25, 2016 at 19:18
  • $\begingroup$ I think you need to devise a really strong motive for studying this planet, or change the atmosphere. You also need a good reason why studying it needs people on the spot, rather than in orbit supervising robots. $\endgroup$ Jul 25, 2016 at 20:30

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