STS-107, Chronicle Of A Disaster Foretold?

[airship]

I thought that a separate thread to discuss the probable causes of the loss of Columbia was called for, as a mark of respect to those expressing their sentiments over the loss of life in the first.

My concern is that an initial incident, possibly resulting in the eventual loss 15 days 22 hours and 22 seconds into the mission, namely that of the impact of foam insulation debris at launch on the shuttle's left wing was never considered dangerous enough to warrant further action.

NASA's announcements so far regarding this event include statements that any damage from the incident was assessed as not representing a danger, that there were no on-board capabilities to visually examine the area of the wing in question, nor any capability by the crew for repairing any damage sustained to the tiles.

My observation is that the tiles, and any questions relating to them are of prime importance for obvious reasons. The questions I have include:

1) Why did NASA discount the incident at launch?

2) What, if any measures did NASA take to inspect the left wing during the mission (eg) by land or space-based telescopes etc. ?

3) Had the incident at launch time been taken seriously, what options would have been available to NASA in order to save the crew (eg) launch of another shuttle, diversion of the shuttle to the ISS etc. ?

As in "normal flight" incidents, while the "primary" cause may have been an equipment failure, the reason for the eventual disaster may well lie in "human error".