Do you think the Challenger was blown up intentionally? If so, why?
To put a stop to our space program which indeed happened for quite a few years afterward.
If I recall correctly (and that's a big if), before the Challenger, spectators were allowed to get close to the launch. When the space program started up again, you had to be miles away.
A rifle shot could have caused the explosion and it would look like an O-ring failure.
</tinfoil hat>