Was the Challenger explosion a “normal accident”? In a narrow sense, the answer is no. Unlike what happened at ., its explosion was caused by a single, catastrophic malfunction: the so-called O-rings that were supposed to prevent hot gases from leaking out of the rocket boosters didn’t do their job. But Vaughan argues that the O-ring problem was really just a symptom. The cause of the accident was the culture of NASA, she says, and that culture led to a series of decisions about the Challenger which very much followed the contours of a normal accident.