Fire Burns Differently In Space

New submitter black6host writes with this interesting snippet from Space.com: "NASA is playing with fire on the International Space Station — literally. Since March 2009, the space agency's Flame Extinguishment Experiment, or FLEX, has conducted more than 200 tests to better understand how fire behaves in microgravity, which is still not well understood. The research could lead to improved fire suppression systems aboard future spaceships, and it could also have practical benefits here on Earth, scientists said."

Comments

There is no FIRE IN SPACE YOU DUMBA

[Anonymous Coward]

Oh my god what are you idiots d

Re:There is no FIRE IN SPACE YOU DUMBA

[dubsnipe]

Well, as long as there is oxygen around, things should combust.

Re:There is no FIRE IN SPACE YOU DUMBA

[show me altoids]

Yeah, but with no convection to carry away the combustion byproducts and bring in more oxygen, it is much more difficult.

Re:There is no FIRE IN SPACE YOU DUMBA

[syousef]

Well, as long as there is oxygen around, things should combust.

Sure, in a crude way you're right and there are a lot of electricals and combustibles on spacecraft. But HOW does it burn when there is no UP? We're so use to hot air rising that our everyday ideas of how to deal with a fire, like get down low, will not work in space. These are ideas that save lives here but are of no use if a fire were to break out. We can only develop new ideas if we get some direct experimental experience. Also it may lead to an ability to harness the differences inherent in a zero g process for industrial/manufacturing processes (but I'm just speculating here). This is worthwhile basic science.

Re:There is no FIRE IN SPACE YOU DUMBA

[necro81]

Which indicates there is a simple and obvious solution for extinguishing a fire in a spacecraft: just vent it out to space. The astronauts can just hold their breath, right?

Re:There is no FIRE IN SPACE YOU DUMBA

[Dan East]

I would think that the worst possible thing (or best possible thing, from Invader Zim's viewpoint) that could happen with a fire in zero G is air flow / turbulence. If there isn't any movement of air, then the oxygen surrounding the fire is consumed and the fire burns very slowly. Since convection currents are a product of gravity, they don't occur in zero G so no fresh O2 is sucked into the fire for combustion as it does here on earth. So I would think anywhere there is an air vent blowing air, or even people just moving around in the environment, you'd have blowtorch like fire forming where the air is disturbed. I bet you could literally see the turbulence in the air as wisps of flame. Kind of disturbing to think of.
An example of this is in a swimming pool. Have you noticed that if you hold very still in motionless, cold water, that you will begin to feel warmer, but as soon as you move it feels cold again (and no, I'm not talking about heating the pool with your pee). That is because the molecules closest to your body heat up, and since they aren't flowing and being replaced by colder molecules, only conduction takes heat away. It's sort of the same principle with fire in zero-g, where the fuel has consumed the oxygen near it (and it is also surrounded by combustion byproducts as well), so as long as fresh air isn't wafted into it, combustion almost grinds to a halt.

Re:There is no FIRE IN SPACE YOU DUMBA

[Anonymous Coward]

That's a nice notion. However, there's a wicked problem with the bends. People say "your blood will boil", but that's not actually what happens; the bubbles will be dissolved gasses coming out of solution. even if you go with a straight oxygen environment (which we learned was a "bad idea" in the Apollo program), the oxygen dissolved in the astronaut's blood will come out of solution. Unfortunately, it won't dissolve again very quickly, which will leave you with bubbles in bad places, like the brain and lungs.

You're also making the assumption that you have enough stored gas (call it air) to repressurize the spacecraft. Even if you live through the depressurization and repressurization, you haven't addressed the source of the fire, which will likely re-ignite. As long as spacecraft are small, gold-plated things, designing to current fire specs is a given. However, as they evolve into large vehicles, designing fire-proofing into everythign will become less and less feasible. People will want to bring clothes and food and shit like that.

The other major thing to be considered is that while droplets behave differently, we also haven't looked at explosive combustion. I suspect it will be very similar. However, we might find that it's very different. Right now we cover military pilots in polyaramids, and accept that paying passengers are probably going to die in a flash fire. The assumption behind the flight suit is that the pilot's on an O2 mask, and so the lungs will be protected. Flash fires might behave very differently, and fire is a complex, complex beast.

I've lived through a fire in an airplane, and it's scarry as fuck. Fortuantely, the aerospace community is very aware of it and designs against it.

Re:There is no FIRE IN SPACE YOU DUMBA

[MozeeToby]

It's not as totally and completely insane as it sounds. Generally, people will recover from exposure to vacuum on their own if the exposure is short (less than 30s) and with surprisingly minor injuries if exposure is less than 90s. And that's without training and a warning of what's going to happen, given proper planning and equipment I suspect you could push the survival rate to the high 90%s, maybe even to two 9's.

Given the choice between burning to death in inescapable zero-g fire and an automated 15 second emergency purge, with a quick re-pressurization system, O2 masks for quicker recovery, and the ability to manage air pressure afterwards to treat the bends... personally, I'd give it a shot. The only real question mark is if the source of the fire has been taken care of. If it's an ongoing short you might find yourself in the same boat you started in, but even that could be addressed by re-pressurizing the spacecraft with nitrogen and relying on O2 masks for the crew until everything is straightened out.

Re:There is no FIRE IN SPACE YOU DUMBA

[Anonymous Coward]

There's still convection (heat/mass transfer by movement of fluid). Air still moves. The heated gases will expand and flow away from the fire, probably in a not entirely uniform way. And I would imagine that airflow from other sources (ventilators, moving objects) also exists. You don't have the expected convection from hot gases rising, that's why they're looking into how fire works in microgravity, because it works differently.

Re:There is no FIRE IN SPACE YOU DUMBA

[bberens]

I would be quite shocked to find that there wasn't constant airflow in the space station. It's not going to be a wind tunnel in there but there's going to be constant circulation from temperature control systems, whatever they use to filter the excess CO2 out of the air, etc.

Re:There is no FIRE IN SPACE YOU DUMBA

[stealth_finger]

There goes stop drop and roll, would be more like Stop and remain motionless.

Pretend the fire is a T-Rex.

Re:There is no FIRE IN SPACE YOU DUMBA

[Lifyre]

There is and it was the same with the space shuttles etc... if you lost something there was a good chance you could find it sucked up against in exhaust vent.

Re:There is no FIRE IN SPACE YOU DUMBA

[tmosley]

Pretty sure boiling means the phase transition between liquid and gas.

Re:There is no FIRE IN SPACE YOU DUMBA

[Bob-taro]

People say "your blood will boil", but that's not actually what happens; the bubbles will be dissolved gasses coming out of solution.

Um, that's the definition of boiling: Dissolved gasses coming out of solution. Can be induced by heating the fluid, lowering the atmospheric pressure, or both.

I'm not sure either of you are right. Boiling is when something changes state from liquid to gas. If you lower pressure enough, your blood (the water in it anyway) would literally boil at room temperature. However, decompression sickness - gases coming out of solution - is a different phenomenon that would probably happen first (at a higher pressure).

Re:There is no FIRE IN SPACE YOU DUMBA

[mr1911]

Okay, there's no GRAVITATIONAL convection, which is the dominant method that enables fresh oxygen to get to a fire in the earth's atmosphere.

Don't tell that to fires. Fires often create their own convection due to a variety of factors.

Re:There is no FIRE IN SPACE YOU DUMBA

[Anonymous Coward]

You require 3 things to keep a conventional fire going. Heat, fuel, and oxygen. The fire would not spread outwards unless there was fuel to burn as well. The same was that a campfire doesn't just keep spreading outwards away from the fire pit, since all the wood (fuel) is in the pit. Now if you were to spill a container of oil or other combustible liquid inside the space station, and then set it on fire. Now the fire could theoretically spread outwards in all directions as the liquid also spread outwards.

On Earth, most fire suppression systems work on removing the heat and to some extent oxygen from the fire triangle. We use compressed CO2, which cools the area as it expands while also displacing some of the oxygen. Or by dousing it with a lot of water, which again cools the surrounding area and displaces some of the oxygen with steam.

In a space station, I think the easiest way to stop a fire would be to vent the atmosphere since removing the oxygen would kill the fire right away. Though the downside is that humans also require oxygen so it'd kill any crew members in that section as well (Assuming they weren't in protective suits).

Re:There is no FIRE IN SPACE YOU DUMBA

[The_Crisis]

So you get a bubble of low density CO2 around the fire, but not any movement

That's correct, except for the parts where it's backwards and/or wrong. The heat given off as the product of combustion should increase the pressure of CO (and/or other products of combustion) (see: Charles' Law) which we are guessing would radiate away in all directions. That pressure increase should cause airflow from the area of higher pressure to the area of lower pressure (see: Wind). So (totally guessing/hypothesizing here) it seems to me that the heat generated as a result of combustion would increase the pressure and cause airflow away from the center of the combustion source which would prevent much if any O2-rich air from circulating, in effect choking itself out.

Re:There is no FIRE IN SPACE YOU DUMBA

[Anonymous Coward]

If I remember right: ISS, MIR... are/were very noisy because everything electronic has to be cooled by forced convection (fans). Without natural convection even a low powered circuit board that would easily dissipate the heat on Earth could eventually overheat in zero G as the heated air just sits there next to the components.

Re:There is no FIRE IN SPACE YOU DUMBA

[Guppy]

If you don't release pressure from your lungs as the ambient pressure decreases (when diving, by ascending), you'll do catastrophic damage to your lungs.

Not holding your breath in a vacuum presents another problem though. Gas exchange in your lungs is a passive process, driven by concentration gradients. As the partial pressure of O2 in your alveoli drops to zero, the diffusion goes into reverse; blood passing through your lungs actually has its remaining oxygen content sucked out, causing you to black out almost instantly.

Re:There is no FIRE IN SPACE YOU DUMBA

[a whoabot]

What you, grandparent, and great-grandparent have overlooked is just how inveterate motion is. Matter is always in motion above zero degrees Kelvin. The environment of the space station is going to be around room temperature, well above 0K, meaning lots of atomic motion. The molecules of this CO2 "bubble" will quickly disperse as they follow down their concentration gradient. Conversely, molecules of O2 will quickly reach the flame as they follow down their concentration gradient. The astronauts could stop oxygen from getting to the flame by sealing it, but not by staying very still.

Re:There is no FIRE IN SPACE YOU DUMBA

[camperdave]

Islands in the Sky by Arthur C. Clarke. A kid wins a contest and wins a trip to a space station as the prize. While on board he learns about microgravity environments, and due to an emergency, gets to travel to various other stations (a Zero G hospital, a communications station, a space hotel). A good, light read.

Obligatory

[mattie_p]

Screaming is different, too, from what I've heard. Or did I?

Re:Don't Yank our Funding

[bmo]

but I'd be curious if anyone has any idea what the practical benefits of this experiment could be.

Without basic science, you don't get applied science.

I sure wish the know-nothing "hurr why study fruit flies? hurr!" idiots would fucking understand this.

But no. They get in their cars and drive, use computers, talk on cellphones, dance at the club to kilowatts of audio, eat, drink, and be merry and then decry the amount of money we spend on basic science to make all that possible.

Don't like money spent on basic science? Go live in a yurt.

--
BMO

Re:Why?

[N0Man74]

Are you referring to the WDEHTBSSAA effect?

What's the big deal?

[smooth wombat]

We all know what to do if a fire breaks out in a spaceship or station. Didn't you people watch Red Planet?

You grab your fire extinguisher, point it at the fire, release the locking pin, pull the handle and get propelled across the room due to no gravity holding you in place and the fire retardant being ejected from the nozzle

Come on you geeks, get with the program!

Re:In case of fire:

[2fuf]

relevant: http://www.youtube.com/watch?v=iSqOqRACxUM (fire at the MIR station)

Re:Don't Yank our Funding

[Anonymous Coward]

Don't like money spent on basic science? Go live in a yurt.

We all know what a yurt is, but the types that you are referring this question to will laugh at you thinking you can't live inside a yogurt...

Ob "benefits here on earth" debunking

[Rogerborg]

If you're trapped in a free-falling elevator, whether it's on fire or not is probably the least (or briefest) of your worries.

Re:Don't Yank our Funding

[JasterBobaMereel]

One day sir, you may tax it. - Faraday's reply to William Gladstone, then British Chancellor of the Exchequer (minister of finance), when asked of the practical value of electricity (1850)

Re:Don't Yank our Funding

[mcgrew]

You do know that we went from the founding of this country to 1913 without an income tax, right?

There was no income tax, but there was taxation. My grandfather was 17 years old in 1913. Few know (as far as I can tell) that when the federal income tax was enacted, only the rich were taxed.

The tax was to pay for a war, which is pretty much where most of your federal income taxes go anyway.

Without income taxes you would not have the interstate highway system (which, incidentally, was built by a Republican administration). I was a little kid when they started building it, and I remember that getting from St Louis to Springfield was a three or four hour drive, vs the hour and a half (or less) on the interstate.

Without federal income taxes you would not have the hoover dam. Americans would not have landed on the moon. America wouldn't have been able to reap the financial winfall of rebuilding Europe after WWII.

The only downside to taxes is that you're a greedy selfish money grubber. Since you seem to be a tea party type, you probably consider yourself to be a Christian (hint: there are no Christians in the Tea Party, it is definitely against everything Jesus taught), you might want to open that bible you like to thump and read Matthew 22:21.