[Iwentsouth]

In this case they didn't know until after they reviewed the tapes of the launch. That was the next day so too late.

[Froggie]

Heard Nasa scientist/astronaut saying that there would have been NO way to do any type of rescue mission, as the Columbia was incapable of docking with the space station, and there was no way for any space walk repair or inspection. They had to know that if there was significant tile damage that there was significant peril on re-entry. Did the astronauts know this? I hope not! but suspect they did. My only question is, if they did have suspicion that there was increased risk, why didn't they plan to land in California, so that any break up would have occurred over the pacific ocean to minimize the risk of damage/injury/death to the populace by falling debris. The only answer is that those in charge didn't calculate the risk as being great - and to second guess them, without possessing their kind of knowledge and training is ridiculous.
Exploration carries risk - sometimes great risk, but we will persevere, face those risks and continue our quest for knowledge.