Now, A Fourth Crack

NASA engineers have discovered yet another crack in the external tank mated to space shuttle Discovery. So far, the agency is still aiming to go in the next launch window, which opens November 30 and closes around December 6.

As NASA continues to find cracks, the question must be asked: Did NASA miss these cracks before, or is the external tank cracking as it sits on the launch pad? If inspections missed cracks until now, that's a serious problem at the tail end of the shuttle program. If this is simply a bad external tank, how it got past quality control is another matter. Launching with this tank is surely being reconsidered, or will be if another crack is found.