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As we spend more time in space, we are going to find out how things burn in space. So it might as well be in controlled circumstances!
NASA's released the videos of its Saffire II experiment, in which the space agency borrowed the Mythbuster's incendiary habits and burned stuff in space. It's all in the name of science, naturally: as we noted on Monday, the agency wants to know how things burn in low gravity, so they can work on better fire control techniques …
In the videos I see what looks like a flame travelling from right to left. Here on earth flames go up because the burning gases are lighter than the surrounding air. In zero G there is no concept of lighter, so nothing should go anywhere, the fire would quickly be staved of oxygen and go out. True the article refers to low G, rather than zero G, but would that difference be enough to account for the movement of the flame? Is the experiment forcing air across the seat of the fire. This is not an unreasonable thing to do because I'd assume that the air in a human habitable module would be constantly blown around to stop the 'nauts from suffocating on their own CO2.
The sideways flame... two theories:
1) That the flame is continuously ventilated, so the fire acts like it would before the fire suppression systems stop circulating oxygen in an emergency situation.
2) As the materials are in a closed area (the test vessel) the expansion of the gases due to the heating (and also the additional pyrolytic gases increasing the local pressure) leads to a constant movement of the burning vapours away from the centre of the fire, which in this instance means movement from the right of the container to the left.
Personally, I'd put my money on 1.
"In the videos I see what looks like a flame travelling from right to left."
I figure it's because of the decaying orbit.
Since the module is decelerating, the heavier, cooler air gets 'forced' to the front, pushing the lighter, hot gasses to the rear.
Just a guess.
I'd assume that the air in a human habitable module would be constantly blown around to stop the 'nauts from suffocating on their own CO2.
Not necessarily. Nothing could STOP the CO2 from diffusing into the atmosphere. Same principle as an airship. Air inevitably leaks into the gas container, but it doesn't settle on the bottom. The whole contents become contaminated and have to purified.
No wonder I have so much trouble getting across to my students that there is gravity in space when the BBC, the Press and here talk about low/zero gravity rather than low/zero G.
Flames tend to pulse in space. The oxygen in the immediate surroundings gets used up so the flame goes out, oxygen rushed in and reignites it, repeat. So maybe that is the green flashing.
If the capsule the experiment is in is spinning, then the hot gases would go preferentially toward the spin axis. Alternatively, if the capsule is decelerating due to atmospheric drag even a tiny amount, it might be enough to cause the flame to go preferentially in one direction.
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