Twenty years ago today, the Space Shuttle Challenger exploded shortly after lift-off, killing its crew.
The cause was a rubber "O-Ring" which couldn't cope with changes in temperature, despite the crucial need for it to expand and fill a gap in a joint. The story of the investigation is covered in great detail by legendary physicist Richard Feynman in his book "What Do You Care What Other People Think?"
AFTERTHOUGHT: I thought it only fitting to remember all those who have died in space programmes. Wikipedia has an article on this here.
I guess it is a measure of communication technology that I heard of Challenger when I woke up and turned on TV-AM on ITV; whereas I saw the Coloumbia disaster as it happened on Sky News. The Coloumbia was lost 1 February 2003.
One comment after the Coloumbia went something like: flying a shuttle looks routine, but it's not - space flight is still a dangerous business.