Having said that, I feel that it is counterproductive for some to react as defensively and dismissively as they sometimes seem to toward questions and comments by the latter, for the simple reason that every American is a stakeholder of sorts in the space program and has a direct financial interest in it (that is, if you pay taxes).
It is not a requirement to be a rocket scientist to ask questions and make suppositions about this horrible tragedy, and you do not have to have a working knowledge of orbital mechanics in order to hold an opinion on the subject. To paraphrase Sen. William Smith, the committee chairman of the government inquest into the Titanic disaster, "How do you trained, professional mariners and seamen manage to keep doing this sort of thing?"
While it is tragic, it is not a "horrible tragedy". It was an accident. Accidents happen. Sometimes people make mistakes. NASA has a very good safety record over the years. This is definitely a situation where we must move on.
Not only doing "that sort of thing" but celebrating the doing of it, a vain and glorious Endeavour. Nature and Nature's God, however, take a colder and truer read of things.
It's not that we shouldn't build big ships -- we must! It's that we'll never have a sea full of USS Titanics, because reality isn't quite affine to that vanity. So the sooner we cotton to reality -- to safety, surety and put "risk" in a well-circumscribed place -- the sooner we all move on from many sadnesses.
It is a great and true of the US culture that we ARE indeed fond of preserving life and put great stock in it.