As part of the Cool Flames Investigation with Gases (CFI-G) project led by fire protection engineer Peter Sunderland of the University of Maryland, attempts to light hot diffusion flames were made in zero-G for six months, but none morphed into cool diffusion flames after being snuffed out. “Cool diffusion flames require very low gas velocities because the chemistry is so slow,” Sunderland tells SYFY WIRE. “On Earth, even a candle flame generates velocities a hundred times higher because of buoyancy. We have recently seen some cool diffusion flames on Earth, but these require tricks like heated air and added ozone.”