There is one big difference between the Shuttle and all the WWII airplanes and fighters: When a bomber was being shot down, there were two others coming off the assembly line to take its place. While the human losses can never be discounted, the uncomfortable truth down at the bottom is that we have a hell of a lot more astronauts than we have orbiters. We are down to three, and sooner or later, someone's luck will run out again and then there will be two.

I don't know how long it will take to figure out either a NASA or private replacement to put people in orbit, but the clock is ticking. Unless we want to rely on Russians and expendables to service the Space Station from now on, which could be done if it had to.