[QUOTE=groundbum;10565914
<< valid points >>
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Hundreds of highly skilled experienced people would have been in on it. Why did not one man/woman speak up?
G[/QUOTE]
A few possibilities, not of course mutually exclusive:
A: One or more did but their concerns were brushed aside and they did not feel they could safely escalate. This brushing aside is more likely if they were 'observers from the side' rather than in the direct engineering flow.
I often find that someone not in the thick of things is more likely to notice something apparently obvious.
B: Lack of full global context, each part can appear to be specified/working correctly if viewed narrowly. This is a counterintuitive possible result of very detailed specifications that focuses on what/how and omit why.
C: The 'boiled frog' : Incremental small (and in this case some not so small) changes can be hard to track and the end result can have problems that are missed that would be obvious on a clean slate analysis.
D: Normalization of deviance: (See Nasa, either shuttle disaster) In this case it could be "Well STS has been working well, this is just a small addition to STS", missing the question of whether STS was a good idea in first place. (I have nowhere near enough knowledge to have an opinion on that)
Combine any/all of the above with outright top level pressure to get this out the door and the result is what we have seen. It will be very interesting to see what becomes public of any legal discovery actions, would not be surprised if internal warnings (item A) come to light.