Misconceptions!!!

In 1985, NASA estimated that the probability of an accident occurring to the space shuttle was 1 in 100,000. But on January 28, 1986, only the 25^th shuttle launch, Challenger exploded after take-off, killing all seven astronauts aboard, and on February 1, 2003, the 113^rd mission, Columbia exploded on re-entry, again killing all seven astronauts. Earlier estimates by other groups had estimated the probability as being closer to 1 in 100, a probability that seems more reasonable.