Their inspection revealed that the laminated lining of one of the two rockets’ nozzles, designed to be eroded slowly away during flight to protect it from the plume of superhot gases escaping from the end of the booster, had been eaten almost completely through by flaming exhaust. They calculated that if the rocket had burned for just eight or nine seconds longer, the spacecraft would have been destroyed, killing all five astronauts on board: the most catastrophic accident in NASA history.
