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Soot forms in fuel-rich combustion chambers, fuel-cooling nozzle walls and turbopump gas generators, and is partly consumed in the hot plumes.

At one point he describes a rocket engine turbopump, which forced liquid hydrogen and oxygen into the combustion chamber and had to go from a standing stop to 38,000 rpm in less than a second, as about the size of a “Christmas cake,” whatever that is.

NASA's independent review team said last week that the initial fire was caused by friction from rubbing parts in a turbopump in one of the rocket's old Russian-built engines.

Orbital said the cause of the failure was most likely a manufacturing defect in a turbopump in one of the rocket’s two AJ-26 engines, a Soviet-era motor refurbished and resold by Aerojet Rocketdyne Holdings Inc. Aerojet in September paid Orbital $50 million to settle the dispute.

Both investigations said a fire and explosion in the rocket engine’s liquid oxygen turbopump caused the booster to fail about 14 seconds after liftoff from Wallops Island, Virginia.