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I am trying to describe the exploration of an hypothetical planet with a hydrocarbon rich atmosphere. Atmospheric pressure is around 1 bar, temperature around 10-20 Celsius, the main component of the atmosphere is methane, around 80%, the rest being water, CO2 and other gases.

I am trying to see if it is possible for the exploration party to use fire, at least for producing light and preparing food.

A quite obvious solution is to have them use a canister of oxygen attached to a burner like we have in Earthly methane kitchen, where oxygen and methane get mixed and then burned.

I want to see if there is any way to have something a bit more "wild" looking, like a bonfire.

Is it plausible to have a substance which:

  • is solid
  • decomposes with heat
  • while decomposing releases oxygen
  • bonus point if it is something which can occur naturally, given the right conditions

I am not concerned about the color of the flame: a bit of sodium can be added to make the flame more suited for producing visible light if needed.

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  • $\begingroup$ '... use a canister of oxygen ...' -- just a note -- there is no such thing as canister of oxygen (not above -120 degC at least). You can have a (heavy) pressure tank, but than the weight of tank will be many times higher than oxygen stored inside (and you need more oxygen mass than carbon mass for burning). But neither methane can be liquefied under room temperature (so no light canister either, you was thinking propane maybe?). Possible solution would be to produce oxygen by chemical reaction (same as done with methane stove actually). $\endgroup$
    – Martin
    Feb 18, 2021 at 13:57
  • $\begingroup$ @Martin: Certainly you can have canisters of oxygen. See a good dictionary, e.g. dictionary.cambridge.org/us/dictionary/english/canister $\endgroup$
    – jamesqf
    Feb 18, 2021 at 17:58
  • $\begingroup$ Does your planet have native life? If so, then there will probably be biochemistry that allows something akin to burning, just as a wood bonfire is basically just speeding up the oxidation reactions that would normally occur during decomposition. $\endgroup$
    – jamesqf
    Feb 18, 2021 at 18:01
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    $\begingroup$ @jamesf English is not my native tongue, so I trust you (but I still can not help myself but imagine canister as a thin walled thing only -- propane canister is ok to me, but not oxygen). Nevertheless, my point was that carying around enough "packed" oxygen for cooking etc. would be order of magnitude heavier than doing the same with propane-butane mixture on Earth. $\endgroup$
    – Martin
    Feb 18, 2021 at 18:09
  • $\begingroup$ One issue with having a hydrocarbon atmosphere & trying to use it as an on-the-go fuel will be controlling its concentration with oxygen. Too little or too methane concentration & it will not burn. In Earth's atmosphere, methane will only burn when its concentration is between 5% & 17%. $\endgroup$
    – Fred
    Feb 21, 2021 at 6:29

4 Answers 4

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The wonderful world of chemistry is full of oxidising agents that would fulfill your requirements, but I'd say the one that's perhaps most familiar to people will be saltpetre, or potassium nitrate. It exists in a natural mineral form, and can obviously be produced in bulk by pre-industrial means that are well over a thousand years old.

Sodium nitrate would also work... once known as "Chilean Saltpetre", it occurs naturally there in mineral form and was commercially exploited. It could be a source of sodium for your pretty firework needs. In the real world it is deliquescent (eg. it'll go soggy from moisture in the air; a bad thing if you wanted to burn it) but that might be less of a problem in your alien environment.

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Sodium chlorate will sustain a fire in this environment

Leaving aside where it comes from for the moment, this is literally exactly what you need. A solid, that when heated (even in an oxygen deprived environment) to over 260 degrees C will emit oxygen and more heat, until all its mass is converted to salt and oxygen.

This is such a wonderful oxygen generator that it's what produces the oxygen in those drop down oxygen masks in passenger aircraft. Its exothermic and will self sustain a fire even in a sealed oxygen-free chamber. See the crash of ValuJet Flight 592 for an example of how much heat and oxygen these things can put out in a sealed room.

We usually see it as a powder, but when exposed to a little bit of water in the atmosphere clumps together into something that could conceivably be thrown on a fire rather than "sprinkled".

Now where does it come from? Technically this doesn't occur in nature; This is easy to produce in bulk as a fertilizer. Now I'm led to believe there are alternative way to produce this by what I'm reading about electrolysis alternatives but I lack the chemistry knowledge to give you a clear natural process to create it.

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    $\begingroup$ A few references applicable to this: Chlorate Candles, Oxygen candles & Chemical oxygen generator $\endgroup$
    – Fred
    Feb 18, 2021 at 16:05
  • $\begingroup$ We used something like that in the Navy for breathing while fighting fires. After use, we would have to lean over a bucket of CLEAN water and let it drop—don’t touch or you get burned. The water had to be clean, because if there were any petroleum products in it, an explosion would be likely. For this reason, I don’t think this is a good idea in the environment mentioned. $\endgroup$
    – WGroleau
    Feb 18, 2021 at 22:43
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Hydrogen Peroxide

Hydrogen Peroxide has historically been used as an oxidizing agent in rocket fuels. In your Methane rich environment, the heat of a flame would cause Hydrogen Peroxide to break down into water and oxygen. The oxygen would then react with your methane creating sustained combustion. While there are more efficient oxidizers like Chlorine Trifluoride, the H2O2 does not make toxic byproducts which you want to avoid with the applications you have in mind.

It is also relatively cheap/easy to mass produce compared to other options. Since your explores are in a remote location, you do not want to need a giant chemical plant to make the stuff, but using the Anthraquinone Electrolysis method (see: https://news.mit.edu/2019/mit-process-could-make-hydrogen-peroxide-available-remote-places-1023), your explores can produce as much hydrogen peroxide as they need using only water, electricity, and anthraquinone which can be infinitely recycled.

This would allow not just exploration of the planet, but a potential for long term habitability.

What about:

is solid

bonus point if it is something which can occur naturally, given the right conditions

Now this part will be a bit more of a stretch since it will depend a lot on the biology of your native lifeforms. On Earth, the highest concentrations of natural hydrogen peroxide are found inside of plants and animals, but still in relatively small quantities... that said, perhaps your organisms use it differently then we do on Earth. Theoretically, your native life forms could use H2O2 instead of glucose for energy storage. If this is the case, then your plants could have large concentrations of H2O2 inside of them; so, your explorers could just cut down the local flora, and burn it just like we do with wood here on earth.

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    $\begingroup$ Peroxide can be made to spontaneously decompose with the right catalyst... a little bit of silver or platinum wire would do as a firelighter, and be re-useable. The tricky thing will be having the right sort of burner, so the methane reaction isn't extinguished by steam (of which there will be quite a bit). $\endgroup$
    – Starfish Prime
    Feb 18, 2021 at 15:21
  • $\begingroup$ Doesn't hydrogen peroxide have a relatively short shelf life because it spontaneously decomposes? Might be a problem for the explorers. $\endgroup$
    – GrumpyYoungMan
    Feb 18, 2021 at 16:08
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    $\begingroup$ @GrumpyYoungMan Yes, it only lasts about 3 years if properly stored, and a few months if not stored properly. But, part of why you would use Hydrogen Peroxide is that you can make it on demand as long as you have water; so, your explores can make it locally instead of being limited to what they can carry. I've added more details. $\endgroup$
    – Nosajimiki
    Feb 18, 2021 at 16:44
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Thermite!

thermite bonfire

source

Gather round the Thermite bonfire you all! Goggles recommended. Iron oxide is solid but with enough heat and some willing aluminum it will give up its oxygen. A very bonfirey heat and light ensues. You can keep your bonfire wires in the hold of your ship and produce a merry fire wherever you touch down.

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  • $\begingroup$ Can you cook over thermite? I believe it would burn too fast and hot to be good for cooking... but if you have a source that says otherwise I would be VERY interested to see that. $\endgroup$
    – Nosajimiki
    Feb 18, 2021 at 17:09
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    $\begingroup$ Ah, @Nosajimiki. I can imagine one who had only seen nuclear bombs might be skeptical of the prospect of a nuclear power plant. Or someone who had only seen Molotov cocktails be skeptical of an internal combustion engine. Thermite is an exothermic reaction like any other. An uncontrolled ball of thermite is fine for welding but if you want a more measured reaction for your thermite powered steam engine you can attenuate or quench the reaction. The method to achieve that will be determined experimentally. $\endgroup$
    – Willk
    Feb 18, 2021 at 21:24
  • $\begingroup$ @Nosajimiki - as regards cooking one can find on YouTube many thermite cooking endeavors. Seared steaks! $\endgroup$
    – Willk
    Feb 18, 2021 at 21:25
  • $\begingroup$ Okay, I've watched a few youtube videos on the topic, and I agree, you CAN cook with the stuff... but I don't think OSHA would be very happy about it. youtube.com/watch?v=yTFafneZfew , youtube.com/watch?v=UPoJFL-l9jw My scepticism about thermite is that it only ignites at temperatures of >1650°C; so, I don't think you can get it to sustain a reaction for a cooler slower burn... but it does win out on coolness points, I'll give it that. $\endgroup$
    – Nosajimiki
    Feb 18, 2021 at 22:48
  • $\begingroup$ @Nosajimiki You technically don’t need to sustain the reaction, you just need a way to capture the heat and release it slowly. That’s not particularly easy either when you’re talking about temperatures hot enough to melt steel, but it’s arguably potentially easier than regulating the reaction. $\endgroup$
    – Austin Hemmelgarn
    Feb 18, 2021 at 23:52

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