If a match is lit in an atmosphere like earth’s but outside of gravity’s pull, will it suffocate? Will it snuff out from its
own gases faster than if it had a steady earthbound updraft to refresh it with more oxygen? I heard the space
shuttle astronauts were doing tests with fire in microgravity. I missed reading any results so all I can do is guess:
it snuffs. My earthist rivals insist fire will burn in zero Gs; some say heat rising will start a draft which in turn
ventilates the reaction. I immediately ask: which way is up? Duh! --John Inkman, Hodgkins, Illinois]
Cecil replied that flames do indeed smother themselves in zero G, but a very slight air current might keep a flame going in zero G longer than on earth.
I can’t help myself, there is another way to keep a flame going in zero G. Given a gradient, chemical species will diffuse away from areas of high concentration toward areas of low concentration. So even in total absence of gravity, combustion products will diffuse away from a flame, and oxygen will diffuse toward a flame (since the flame has created an area of low oxygen concentration). The trick is to have a small enough flame to stay supplied by this comparitively slow process.
A slow burning candle might extinguish itself, but a propane torch (one relying on external oxygen) probably would not, because the waste gasses would be expelled violently from the area, creating a vacumm to pull in fresh air.
[but a propane torch (one relying on external oxygen) probably ]
a propane torch would act as an engine, providing thrust as the expanding gas is forced out one direction (enough to provide thrust), air (O2) is sucked into the gas stream, then combusted as it is shot out the nosel. perhaps the better analogy would be a propane lantern where O2 is supplies naturally (through convection here on good ol’ earth), which would probally snuff, but maby not, perhaps the propane would start to extinguish at the mantel, the gas would then expand outword, possibly still ingited as O2 is present further away. The o2 might not be enought to substain combustion away from the mantel, but just imagine if it were, the propane expanding out and the surface of the propane “ballon” on fire,. WOW!!!
My third posting this week. I don’t want to turn into an internet crank, but I just read this in the book on Apollo 13 by the mission commander, Jim Lovell, and Jeffrey Kluger. It describes trying to sleep on the damaged Odyssey:
As [Fred] Haise floated up the tunnel … he was stunned at what he found… He could clearly see his breath condensing in front of him.
The crew’s two-piece Beta-cloth jumpsuits were not designed for warmth… the thin cloth cocoons the astronauts used during sleep periods were intended merely as restraints … finally, … he gave up, wriggled out of his sleeping bag, and floated down through the tunnel to the LEM.
“That’s it?” Lovell asked, glancing at his watch…
“It’s too cold up there,” Haise muttered… “Too cold and too noisy.”
(But after another day or two…)
The commander rubbed his eyes … and jumped up into Odyssey… The ambient temperature in the command module was by now, Lovell guessed, down in the low forties or high thirties. Around the sleeping Haise, however, a thin layer of nearly body temperature had formed. In the absence of gravity, which meant an absence of convection, the warm air would not be any lighter than the cold air around it, and thus would not rise and drift away.
Helping Haise out of his couch, Lovell scattered the atmospheric blanket his junior pilot had spent the last three hours creating, and sent him down to the LEM.
Wild. Of all the questions in the world, I would have once put this one very high on my list of NO Practical Applications. Just shows me.
One other note of interest about space and flames. One of the major causes of the Apollo 1 fire tragedy was the high oxygen content of the internal atmosphere. Everyone (?) knows that - but here’s why it was especially critical. The design environment was for in space, where they were to run at something like 5 psia pure O2. In order to simulate that on the ground, they had to pressurize the capsule to 5 psi above ambient, thus 19.7 psia, pure O2. 5 psia pure O2 is not that dangerous. 19.7 psia pure O2 makes many of the flame resistant materials into major fire hazards. Even the special flame resistant fabrics they use now will go up like flash paper (well, not quite that fast) in 19.7 psia pure O2. So the fire wasn’t just a problem of pure O2, but the pressure of O2 used and the properties of materials in a pure O2 environment. It is conceivable that if the spark had happened on orbit, it might not have ignited at all, or if it had, the crew would have had time to react and put it out.