system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: how were they able to pinpoint the exact cause of a rocket failure

I'm assuming now engine use real time monitoring systems and sensors. But how were early rocket designers able to determine what caused a rocket to explode like a raptured fuel line or something? Did they just guess?
gpt
Even early rockets had some form of telemetry that that transmitted live readings on the status of certain systems. You could use that data along with visuals (film and still photos) coupled with examining the wreckage, and you could usually get a pretty good idea of at least what major system was the problem. For example, if shortly before a rocket broke up, there was a voltage spike in the guidance computer and the rocket veered off course, you could reasonably trace that error to the circuit in the electrical system that provided power to the guidance computer.