Who'd be mad enough to start a 'large-scale fire' in a spaceship? The next resupply mission for the International Space Station (ISS) will include the kit needed to light a fire in a spacecraft. And NASA plans to strike a match and make it happen. The fire's a NASA idea: it knows that fire in space is dangerous but doesn't know how fire behaves in a zero gravity environment. That means, as …
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The experiment will be started after the craft enters its terminal decent stage to ensure that the experiment doesn't cause the capsule to stay up in space, wrecking havoc. The problem is, that at those speeds, radio communication is next to impossible. Even manned craft go dark during large portions of the return flight.
This is usually due to the craft moving too quickly for a receiver to properly track it; the Doppler shift in the signal being too extreme to communicate safely; or super-heating of the air around the craft causing it to radiate immense amount of very-high frequency noise (Its actually possible to track spacecraft, meteorites, and miscellaneous junk entering the atmosphere by listening for it's "scream" on the HF to Ka bands)
Didn't they make "tests" like that on MIR?
Anyway, this is a very good idea. Fires are tricky enough down here (and sometimes do not behave how you'd expect them to at all). Fires in microgravity will be different. And as weird shit can and will happen, at least try to be prepared.
As part of my job is fire prevention (not in space, alas), I will be following this with great interest.
There have been tests, on all spacestations. Thing is they were really small-scale experiments, under very controlled circumstances, and nothing like the "someone tossed his smouldering ciggie stub in the trash"
Microgravity fires are weird.. hardly any convection, slow-burning, *almost* self-smothering, but retain ignition temperature a lot longer and get hotter overall, so any draft could get them going again with a vengeance. A firefighters' worst nightmare, really.
It will not be anywhere as bad as people think it will be.
A fire in zero G may not even burn unless you set it up in an oxygen enriched atmosphere or support it with electric heating.
The lack of convection is a killer. Any burn will be extremely localized and will "eat" its oxygen allowance nearly immediately smothering the fire in the process.
On earth, convection will take away the products of the burn and bring new oxygen. In zero G there is nothing to do that.
There were several fires on Mir. I think the real problem is that, although what you say sounds sensible, nobody really knows for sure. What if there's a slight air current? Presumably the air conditioning needs to move air around continually. What if the burning material is moving? What if the fire itself generates air currents due to out-gassing of the burning materials?
Although a fire may struggle to reach the intensity of a fire on Earth, in a small, limited environment even a small fire could, for example, potentially eat all the available oxygen very quickly, as you point out. That may not be good for the fire, but it's probably not particularly good for any people nearby either.
"The lack of convection is a killer"
In a real world environment (as opposed to the test ones that have been used so far) things are likely to be very different.
For starters there will be air movement caused by people running around trying to put it out. None of the experiments so far have attempted to replicate that.
Smothering fires has a nasty tendency to start making lots of carbon monoxide from incomplete combustion in any case, so whilst an undisturbed zero-g fire might look unspectacular it could be even deadlier than most people realise.
@Voland's right hand: "The lack of convection is a killer. Any burn will be extremely localized and will "eat" its oxygen allowance nearly immediately smothering the fire in the process."
Well, maybe: they're doing this test to find out what really happens, because they don't know for sure one way or another.
It will not be anywhere as bad as people think it will be.
A fire in zero G may not even burn unless you set it up in an oxygen enriched atmosphere or support it with electric heating...
Y'mean, more or less like Apollo 1?
OK, that was on the ground, but, still... many historians mention that the Apollo 1 fire -- ironically, sadly -- bought time for Apollo Block II development and improvements in fire-safe cabin materials and atmosphere.
I still don't like to think what it would've been like had the infamous "plugs-out test" gone as planned, and Apollo 1 had launched, and that goddamn' fire happened in orbit.
This is not your granddad's Apollo 1 anymore, hasn't there been a requirement around to use only non-flammable construction materials for, well, almost ever? [scratches head]
...Or is it that they came to realize some materials classed as non-flammable still may be ignited, given the right amount of heating?
>Or is it that they came to realize some materials classed as non-flammable still may be ignited, given the right amount of heating?
There is also the scenario of an oxygen cylinder leak, and in such an oxygen-enriched atmosphere many materials that we think of as not flammable can catch fire.
Sadly NASA do have experience of this on Earth. Apollo 1's three crew members died in a launch rehearsal test, because their cabin was pressurized with pure oxygen.
"There is also the scenario of an oxygen cylinder leak, and in such an oxygen-enriched atmosphere many materials that we think of as not flammable can catch fire."
Also, there are better (or at least, more interesting - look up ClF3 for example) oxidisers than oxygen - the potential for them to be present in a space vehicle is obvious.
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