25 years ago yesterday, America lost seven brave people in what can only be described as the worst tragedy in the history of America’s manned space program, the Challenger disaster.

I’ve seen and heard dozens of tributes on radio and television, and read a few in the popular press. They all describe the tragedy as some sort of terrible accident, and the crew as victims of the perils of space flight. All of these tributes seem to gloss over the one important fact that we most need to remember about that day 25 years ago. It wasn’t an accident, and it was preventable.

Many grossly oversimplified explanations claim that “an o-ring failed.” While that’s partially true, it’s misleading. It wouldn’t have failed if it had been used in the way it was intended to be used.

First of all, the field joint’s design was imperfect. When the solid rocket motor fired, the three segments of the motor would expand between the field joints. The field joints themselves, made of heavy metal, could not expand. This caused a phenomenon called ‘joint rotation’ which tended to open the joints a little, decompressing the o-rings and sometimes allowing leakage.

On several earlier flights, there had been leakage. O-rings had burned partway through. Engineers saw this as a sign of trouble, but management was more optimistic and even considered the fact that these leaks had never caused the loss of a vehicle or crew a good sign.

When it was reported to Morton Thiokol, the designers of the solid rocket motors, that a launch was imminent in sub-freezing weather with ice on the pad, the engineers were horrified. They recommended strongly against such a launch. It would be dangerous; any idiot knows that rubber stiffens up when it’s cold, and therefore the rubber O-rings would be slow to expand to fill the larger gap when joint rotation occurred. Management felt differently and told NASA so. The decision was made to launch — a fateful, murderous decision that was completely insupportable.

The lessons we can and should learn from this are numerous. The Rogers Commission found a few. Richard Feynman, working somewhat independently within that Commission, uncovered a few more of which only he found the candor to speak. The bottom line, though, is that when it comes to safety, rare is the case where management overruling engineering has ever resulted in anything good.

The seven Challenger astronauts are not victims of the inherent dangers of space travel. They are not victims of an accident. These seven people were the price of arrogance. They were murdered  by those who found it convenient to place political and financial expedience ahead of sound engineering principle. We will remember them, and we must, unless we are willing to sacrifice more lives to relearn the same lesson.