what would happen if you lit a match on titan?

[smart013]

Its really sad that a website like http://what-if.xkcd.com/ could make so much out of such an interesting question from the OP, but this thread preferred to debate the completely unrelated semantics of nuclear weapons. It may be not an insult, but a deliberatly effort to derail the thread nonseless. Sad.

[ZetaX]

I still do not see why this should be interesting. I already explained why it is not earlier, and some discussed flares and such a bit after. Still not an interesting what-if. The one on jupiter at least spawned some follow ups (but still not enough for a what-if I think).

If you have a good "idea", then post it. I so far found the nuclear bomb semantics a more insightful discussion than the original topic, which was already finished before that anyway.

[cantab]

Well, if you had an oxygen cylinder venting to the air?

Then, what if we tried more oxygen?

[Seret]

LOX would certainly be frisky in a hydrocarbon rich atmosphere.

[lajoswinkler]

Well, if you had an oxygen cylinder venting to the air?

Then, what if we tried more oxygen?

Given that the pressure is 146.7 kPa and temperature 94 K, disregarding methane, density is around 5.2 kg*m^-3.

Density of oxygen in the same conditions is 6 kg*m^-3. That means oxygen would form a cloud close to the ground, unless there's wind to disperse it.

Limits for combustion reaction for methane at standard conditions of temperature, pressure and oxygen concentration are 5-15%.

Lower temperatures make methane-oxygen combustion harder to occur, and there's only 4.9% of methane there, so the answer is - no, you could not ignite the atmosphere if you release oxygen from a cylinder.

There's one exception. If you try to do it near the lakes of liquid methane-ethane, or while it's raining, therefore in an environment enriched with lower hydrocarbon vapors, the probability of reaction starting after being subjected to a spark or a flame are enormous.

Various factors and complex fluid dynamics are determining whether it would be a deflagration or detonation. Diffusion and convection play a huge role in all that.

Edited August 10, 2014 by lajoswinkler

[Capt.Joseph Kerbertson]

I would imagine that the atmosphere is too rich to ignite. Think about a gas can. If you drop a lit match into a full gas can, nothing happens. Match goes out. Why? Too liquid of an environment, not enough vapor. Take a teaspoon of gas out and spread it out and then drop a match... what happens? Pooof. It lights.

[jfull]

I don't think this thread is about whether or not the match would light, its about whether the entire planet would ignite, and the answer is definitely no.

There is no significant amount of atmospheric oxygen there.

[lajoswinkler]

I would imagine that the atmosphere is too rich to ignite. Think about a gas can. If you drop a lit match into a full gas can, nothing happens. Match goes out. Why? Too liquid of an environment, not enough vapor. Take a teaspoon of gas out and spread it out and then drop a match... what happens? Pooof. It lights.

It can't ignite because there's nothing to react there. It's more than 95% nitrogen on the surface.

I don't think this thread is about whether or not the match would light, its about whether the entire planet would ignite, and the answer is definitely no.

There is no significant amount of atmospheric oxygen there.

Satellite, not planet.

There isn't any elemental oxygen on the surface because there can't be. It's a world of low energy, inert gas with a pinch of reducer.

[TheDarkStar]

This thread makes me wonder what would happen if a Titan habitat (filled with oxygen-rich air) was impacted by something large - there would be some sparks and heat, which might start a reaction that would use up most of the oxygen while it reacted with the air; at the same time, it would char the habitat.

[ZetaX]

At least in the beginning, it will probably only burn close to the hole in the habitat.

[crubs]

Actually I was reading a proposal to place an aircraft on Titan with an oxygen as opposed to a fuel tank. The engines would be designed to breathe methane to provide propulsion.

[lajoswinkler]

It would work only if the vehicle would land near a lake and take some of the fluid inside. There isn't enough methane in the atmosphere to support any burning reaction. There's less than 5% near the ground and it decreases with height. Even if the rest of the atmosphere was oxygen, nothing would happen (except near the lakes where methane/ethane fumes are).

I don't understand why does everyone think of Titan as an "oil refinery" world. It's basically nitrogen. It atmosphere is purer nitrogen (>95%) than our air on Earth is, where it's 78%.

Even if the vehicle would supply itself using a lake, it would probably need to purify the stuff. The lakes must be contaminated with tholins and that's probably not something engines would appreciate.