SPACE FIRE!

December 1, 2011 6:22 PM

Fire tests on the International Space Station are showing some really neat results, including that fire can burn in microgravity at lower temperatures and with less oxygen. Video included at the link.

I've been wanting to see video of a match burning in zero gravity for literally over two decades. This is awesome.

posted by odinsdream (23 comments total)

This page has some more video clips without narration and extra graphics.
posted by odinsdream at 6:25 PM on December 1, 2011 [2 favorites]

This leads me to wonder what a microwave oven plasma would do in microgravity.
posted by Tube at 6:30 PM on December 1, 2011

We don't even really understand fire. There's something very beautiful and humbling about that.
posted by Foci for Analysis at 6:37 PM on December 1, 2011 [3 favorites]

...fire can burn in microgravity at lower temperatures and with less oxygen.

"lower" and "less" are comparatives.
posted by DU at 6:52 PM on December 1, 2011

Hey cool only three comments before complaints!
posted by odinsdream at 6:55 PM on December 1, 2011 [3 favorites]

We don't even really understand fire. There's something very beautiful and humbling about that.

I think we understand it, it's just some details that we don't really get. This stuff could probably be modeled on a molecular level.
posted by delmoi at 7:13 PM on December 1, 2011

I see that it's only a small drop of fuel they're igniting, but I bet all the other astronauts give the designated experimenter the stinkeye and make lots of funny-but-no-seriously jokes about being careful.

Because... FIRE ON A SPACESHIP sounds terrifying to me.
posted by empyrean at 7:17 PM on December 1, 2011 [1 favorite]

Because... FIRE ON A SPACESHIP sounds terrifying to me.

My guess is that they try to avoid having a lot of flammable stuff in easy reach, although I could be wrong.
posted by delmoi at 7:29 PM on December 1, 2011

Bloody space arsonists ruining it for everyone.
posted by clvrmnky at 7:31 PM on December 1, 2011

Microgravity combustion research was one of the objectives of the ill-fated STS-107 mission and useful data was obtained, despite the tragic ending.
posted by LastOfHisKind at 7:36 PM on December 1, 2011 [1 favorite]

<>"lower" and "less" are comparatives.

pssst. I think maybe "than on earth's surface" is implied.
posted by Justinian at 7:40 PM on December 1, 2011 [7 favorites]

fire can burn in microgravity at lower temperatures and with less oxygen

Great. Another foreign market undercutting us.
posted by Trurl at 7:46 PM on December 1, 2011 [2 favorites]

"I see that it's only a small drop of fuel they're igniting, but I bet all the other astronauts give the designated experimenter the stinkeye and make lots of funny-but-no-seriously jokes about being careful.

Because... FIRE ON A SPACESHIP sounds terrifying to me."

That is not really where the scientific advance comes in, the Soviets have already thoroughly characterized those variables: Mir Scientists Study Effects Of Weightlessness On Mortal Terror
posted by Blasdelb at 8:27 PM on December 1, 2011

My favorite part:
The way the narrator says "And the same thing happens... with HEPTANE!!!!11!"
posted by SmileyChewtrain at 8:37 PM on December 1, 2011

...And also how totally awesome this is
posted by SmileyChewtrain at 8:39 PM on December 1, 2011

We're just now trying fire in space? Surprising! I would have assumed that a) the French would have contributed a module to the ISS and b) smoking would be allowed in that module.
posted by snofoam at 8:56 PM on December 1, 2011 [2 favorites]

I can just see the first conversation about the experiment.

"You want me to do WHAT?"
posted by arcticseal at 9:00 PM on December 1, 2011

With the cancellation of the space shuttle program it's encouraging to see more hard science coming out that will motivate future interest.

Good science and cheaper costs now that SpaceX has the first private contract to dock with the ISS will hopefully begin to support space age 2.0
posted by wjzeng at 2:20 AM on December 2, 2011

While I know this is actually serious and highly-controlled research, I like to imagine it coming about more as a product of two bored astronauts.

"So, Bob, what do you want to do today...IN SPACE?"
"Dunno, Jeff."
"Nah, I dunno either."
"..."
"Want to set fire to stuff?"
posted by ZsigE at 4:46 AM on December 2, 2011

This stuff could probably be modeled on a molecular level.

*puts on fluid dynamics hat*

Depends on what your definition of "could" is, really. There's a big difference here between what the science tells us and what is practical to actually figure out.

Fire is a very chaotic system to understand. There are chemical reactions taking place, energy being transferred, fluids moving in a turbulent fashion... all of which are governed by complicated equations.

One of the problems with determining ignition points is that it's highly non-deterministic. You might think that, given a known pressure, temperature, and fuel concentration, you could figure out how much energy is required to ignite the mixture. The truth is that these events tend to fall on a curve; over several runs of the experiment, some times it will take more or less energy to ignite than the mean.

Depending on the resolution you want, determining the fluid flow and flame propagation is next to impossible. We can make general statements - "the flame wave will travel outward from the ignition source at x m/s" - but that's about as good as you can get (again because of the stochastic nature of ignition and the chaotic nature of turbulent flow).

Speaking of turbulence, there is currently no way to model it with direct numerical methods. There are equations that can be used to model Navier-Stokes (the equation(s) that govern fluid flow), and you can plug these into a computer to get a good model of your system. However, laminar flow allows us to make certain assumptions that cannot be ignored with turbulent flow (such as simplifying a 3-D system to 2-D, which is a huge time saver).

The number of operations to calculate a turbulent flow system is roughly 10^4 times the cube of the Reynolds number. As an example (because I have these number handy), to model the turbulent flow over the wing of an airliner with a characteristic length of 1 m flying at 10,000 m would take about 10^25 operations. Using a 100 teraflop supercomputer, the simulation would run about 10^11 seconds, or about 3,000 years.

In short: math is hard.
posted by backseatpilot at 5:37 AM on December 2, 2011 [6 favorites]

This stuff could probably be modeled on a molecular level.

As well as backseatpilot's excellent comments, let me also say that these interactions are further non-classical, that is they mostly have to get done by QM rather than Newtonian mechanics if you want to get things even close to correct, even in cases where only carbon, hydrogen and oxygen are involved. This means solving a DE each time as well (with approximate models of the molecular orbitals) instead of simple(r) linear algebra. Chemical kinetics is really hard to get right with approximate orbital theory, reaction energies, notoriously so.
posted by bonehead at 6:27 AM on December 2, 2011

"Continued burning after flame extinction" - anybody know about this? I looked at the FLEX page linked in the first comment and didn't see any explanation. Some of the videos show an afterglow but it doesn't sound like burning to me (condensing vapors cause backscattering of light).

Are they just saying that a tiny bit of remaining fuel continues to oxidize even after visible flames subside (because our eyes aren't as sensitive as NASA's spectrometers) which would be a pretty meh finding, or is it something more interesting?
posted by Quietgal at 8:43 AM on December 2, 2011

I can't find anymore than this quote:

"Thus far the most surprising thing we've observed is continued apparent burning of heptane droplets after flame extinction under certain conditions; currently, this is entirely unexplained," said Williams, who has studied combustion for more than 50 years.

from Science Daily.

Here is the PI's page. He's got a presentation about the experiments here, but that's for the methanol results only (full paper here). I don't think they have published yet.
posted by bonehead at 9:08 AM on December 2, 2011