In January 1986, the space shuttle Challenger exploded shortly after launch. An in-

vestigation was launched into the cause of the crash and attention focused on the

rubber O-ring seals in the rocket boosters. At lower temperatures, rubber becomes

more brittle and is a less effective sealant. At the time of the launch, the temperature

was 31◦F. Could the failure of the O-rings have been predicted? In the 23 previous shuttle missions for which data exists, some evidence of damage due to blow by and

erosion was recorded on some O-rings. Each shuttle had two boosters, each with

three O-rings. For each mission, we know the number of O-rings out of six showing

some damage and the launch temperature. This is a simplification of the problem —

see Dalal, Fowlkes, and Hoadley (1989) for more details.