Imus asked Robert Bazell my question. Did the astronauts know there was serious concern about their safety during re-entry, because of the possibly missing/damaged tiles?
Bazell says he does not know if the astronauts knew specifically about the inter-NASA memo that detailed the dangers, a memo that was written just two days before re-entry. But Bazell says yes, of course the astronauts knew about what happened on take-off, when tiles were damaged, but he doubts they knew about the existance of a specific memo, that has been exposed by Barbree this morning.