This day in enginering history

Today is the day, back in 1986, that the Space Shuttle Challenger exploded on take-off. It was a sad, terrible day. All seven astronauts aboard were killed. This was not just caused by an engineering error, though. It was also caused by management problems in both a government agency and a private company. You can get a detailed article on this disaster on Wikipedia in the "Space Shuttle Challenger disaster" article.

A special investigation found the cause and it was definitely an engineering error. A joint keeping burning fuel from escaping was poorly designed. But also, an O-ring that sealed the joint failed because it was not designed to work under the conditions in which it was being used. But finally, when questions were asked about whether the launch should proceed in such harsh conditions (the temperature was below freezing while the design called for temperatures above 40 degrees Fahrenheit), the managers decided it was an acceptable risk. The joint had already been flagged as a bad design and was being redesigned. But instead of the Shuttle program being suspended until the new design could be used, flights continued.

It seems that disasters of this magnitude are not usually the result of one mistake. They are the result of cascading mistakes. If the launch that day had been postponed, the mission may have succeeded and no lives would have been lost. But what of the next mission? What if conditions were only marginally bad? Would the future missions have been pushed to launch in bad conditions due to the success of so many previous missions?

This happened 27 years ago and I still get a sick feeling when I think about it. I couldn't watch the taped replays of the launch (ending in the break-up of the Shuttle) for years afterward.