Twenty-five years ago, an event occurred that is seared into the memory of most Americans: About a minute after liftoff, the space shuttle Challenger blew apart, killing all aboard, including teacher-astronaut Christa McAuliffe.
The day started off innocently enough. It was unusually cold in Florida that day, but NASA managers decided to attempt a launch anyway. As a subsequent investigation made clear, the cold temperature made O-rings, which were intended to contain hot gases, fail on the solid rocket boosters.
Link: NPR