The 37-Second Failure | The Software That Flew on the Wrong Rocket

On June 4th, 1996, the Ariane 5 launched for the first time. 37 seconds later, ten years of development, seven billion dollars, and four scientific satellites were gone. Every system on board performed exactly as designed. Every sensor read correctly. Every safety system fired on cue. The cause wasn't a hardware failure or a programming mistake — it was a perfectly reasonable engineering decision, inherited from a rocket that had been flying flawlessly for a decade. This episode traces the cascade from one unquestioned assumption to total loss, and asks: when is "it worked before" not good enough? Topics: software reuse, heritage code, inertial reference systems, integer overflow, redundancy design, the ESA inquiry board, systems engineering, launch vehicle safety.