One blurry image from an Air Force tracking station in New Mexico, taken about a minute before the shuttle disintegrated, shows what some observers have interpreted as a jagged leading edge on the left wing.

CNN: Piece of shuttle left wing identified

That piece of insulation, which fell off 82 seconds after launch, hit the leading edge of Columbia's left wing and caused enough damage to bring about the shuttle's destruction when it re-entered the Earth's atmosphere February 1.

CNN: Columbia probe seeks better monitoring

It remains unknown where the segment fit into the wing, but it included reinforced carbon-carbon material, which protects the leading edge of shuttle wings from the 3, 000-degree Fahrenheit heat of atmospheric re-entry.

CNN: Piece of shuttle left wing identified