Re: Space Shuttle
"The worst bit about the Challenger disaster though was the fact that the dangers of the booster construction had actually been known since 1971 and not addressed until after the disaster."
The boosters were required to be constructed in 2 separate states, which is why they consisted of multiple parts instead of being a single solid tube.
"Even with Columbia, the issue of foam debris hitting the wings at liftoff was known, but downplayed "
It wasn't downplayed, nobody had any clue that the CFRC panels on the edge of the wings could get damaged by the foam, in tests they had shown to be pretty indestructible. They thought the ceramic tiles were the only part that could get damaged and they had a procedure in place for detecting damage to the tiles.
After Columbia broke up they tried to recreate the damage by firing foam blocks at the panels they thought the foam had hit and they couldn't do any damage even after repeated tests. Then one of the image analysts came back and said it might have been a different panel, they set the test up to fire the foam at that panel and the foam smashed a massive hole right though the panel on the first test.
You have to remember that each of the space shuttles was a slightly different size and shape, and small changes to the shapes of panels can affect their ability to survive impacts significantly.
Challenger was the fault of politicians, management and a culture of risk taking. Columbia was an inevitable part of the shuttles design.