The Challenger Disaster

Abstract

[The information given below is from the Journal of the American Statistical Association 84, pages 945-957, December, 1989. Available in the Math Library.] On January 28, 1986 the space shuttle Challenger exploded. Seven astronauts died because two large rubber O-rings leaked during takeoff. These rings had lost their resiliency because of the low temperature at the time of the flight. The air temperature was about 0 o Celsius, and the temperature of the O-rings about 6 degrees below that. 22S:101 Biostatistics: J. Huang 2 On the night of January 27, 1986, the night before the space shuttle Challenger accident, there was a three-hour teleconference among people at Morton Thiokol (manufacturer of the solid rocket motor), Marshall Space Flight Center [NASA (National Aeronautics and Space Administration) center for motor design control], and Kennedy Space Center. The discussion focused on the forecast of a 31 o F temperature for launch time the next morning, and the effect of low temperature on O-ring performance. A data set, Figure 1 below, played an important role in the discussion. Each plotted point represents a shuttle flight that experienced thermal distress in the field-joint O-rings; the x axis shows the temperature at launch and the y axis shows the the damage index to the O-rings. The O-rings seal the field joints of the solid rocket motors, which boost the shuttle into orbit. Based on the U-shaped configuration of points it was concluded that there was no evidence from the historical data about a temperature effect.