Investigators are focusing on Columbia's left wing as they try to determine what destroyed the shuttle, killing all seven astronauts on board.
A piece of insulating foam broke off the external fuel tank about a minute into Columbia's launch on January 16th, smashing into the wing, which is covered with thermal tiles to protect the ship from the extreme heat experienced on re-entry into the atmosphere.
Just a day earlier, NASA had given assurances that the incident was not a reason for concern.
The space agency did an extensive engineering analysis that included a frame-by-frame examination of the launch video, and concluded that any damage to Columbia's thermal tiles would be minor.
However, the independent commission appointed by NASA to investigate the incident is now looking at the possibility that the tiles were damaged far more seriously than previously thought.
The same wing showed sensor failures yesterday, 23 minutes before Columbia was due to touch down. Seven minutes later the shuttle disintegrated over Texas.
Shuttle manager Mr Ron Dittemore said: "As we look at that now in hindsight we can't discount that there might be a connection. But we have to caution you and ourselves that we can't rush to judgment on it because there are a lot of things in this business that look like the smoking gun but turn out not even to be close."
PA