Re:Conversions... (Score 3, Interesting)

Well, I think the most likely candidate is not anything *simple* at all (although human error may certainly be involved). Most catastrophic spacecraft failures (and other engineering failures, for that matter) typically result from a couple of things going wrong in a complex, yet interconnected, way - often referred to as "the failure chain".

In the case of a simple flight software error, not only would the boneheaded engineer that wrote the code have screwed up, but also the organization that is supposed to validate and test the software (and they are usually fairly independent, if things are set up correctly).

Another thing I've encountered with working on NASA spacecraft is that the systems engineering is just a bitch - the thing is so complex nobody really understands how it works from one end to the other. The guidance guys may have this slick new way to do an inertion burn - but they don't realize the duty cycle on the engine will create a heat load that the thermal system can't dissipate - and the thermal guys don't know the first thing about how the engine and guidance works so they don't catch it until it's too late. Misunderstanding of complex systems is often a problem that leads to failures.