http://forum.nasaspaceflight.com/index.php?topic=26960.msg814769#msg814769
In the Challenger disaster,
context is everything. As of 1986 NASA was cornered with the wrong launch system.
They had promised wonders - the shuttle was to fly 60 times a year to earn money, yet that flight rate had been cut to 24, yet 1985 burst at the seams with only 11 launches.
1986 was to see 15 launches, but the real problem was that some of these launches were planetary probes. The nasty thing with that: planetary probes have launch windows.
Galileo and Ulysses were both going to Jupiter in 1986, with a launch window in May. It was really
launch-or-die.
Challenger next mission was to carry some telescope to study comet Halley, and that had to fly on March 6 - or die. Sending a shuttle in low earth orbit to study a comet far away was dumb, but after all, NASA had zero probe, unlike the Soviet Union, Japan or ESA...
Cancelling the Shuttle program was not acceptable either, not after spending $7 billion and building 5 machines, plus designing a space station around it. No way.
No, really, NASA situation was deseperate.
Challenger was horrible, but things could have been ever worse.
In May 1986, a shuttle was to carry a Centaur to boost Galileo to Jupiter. This peculiar shuttle mission would have carried no less than
- 4 astronauts
- 2 RTG with plutonium on Galileo
- 1 Centaur filled with (explosive) hydrogen.
And it could suffer no delays, otherwise it would miss the Jupiter launch window. Oh, and in order to carry the massive Centaur, the SSME were to be pushed to 109% of their maximal usual power - with a final orbit barely 100 miles high. And only four astronauts.
That was the situation in 1986.