Fragment is found from suspect wing of 'Columbia'

A wing fragment that might be the most important piece of Columbia found since it disintegrated came from the space shuttle's troubled left side, Nasa has determined. The fragment includes a 2ft (60cm) piece of carbon- composite panel, a dense material that covered the leading edge of the wing, and a 1ft piece of the wing.

Michael Kostelnik of Nasa called it "a significant recovery" in the investigation of the explosion that killed all seven astronauts. The remnant was found near Corsicana, Texas, 66 miles south-east of Fort Worth, on Friday.

Barely a minute after lift-off, a piece of insulating foam from Columbia's external fuel tank broke off and hit the left wing. Nasa says it did not cause serious damage, but it is still a central part of the investigation.

An avionics box, which monitors and controls the shuttle in flight, has also been found "in fairly good condition".

Nasa has begun transporting 12,000 pieces of wreckage from a 500-mile swath of Texas and Louisiana to Kennedy Space Centre in Florida for reassembly and analysis. There are also more than 1,500 photographs and videotapes of Columbia as it re-entered the atmosphere on 1 February after its 16-day mission.