I'm under the belief that the recent space shuttle disaster could
have been avoided if the VentureStar project hadn't been canceled.
The Columbia could've been retired (it was the oldest space shuttle
in service you know) and the VentureStar could've taken its place.
On the other hand, it's also possible that the VentureStar could've
burned up on re-entry too. But then again it's also possible that a
newer and new brand of space shuttle might have a smaller chance of
catastrophic failure. There are an infinite number of possible
outcomes for this and all other circumstances, so I can't really go
through them all.