NASA investigators have found what they claim is a ‘significant’ section of the wing of the doomed space shuttle Columbia, which crashed last Saturday with the loss of all seven crew.
The shuttle’s wings, including the hardened leading-edge material and heat-resistant tiles are believed to be the most likely source of clues to the tragedy.
Space agency officials told the New York Times they were still uncertain whether the win
g section, which they described as a little more than 2ft long, was from the left wing.
It was the left wing that was struck by foam falling off the central fuel tank during launch. In the last minutes of the doomed mission, the same wing was where sensors indicated ever-worsening signs of distress as the shuttle sped over California to central Texas, where it disintegrated.
The wing section was found near Fort Worth, Texas, which is further west than most of the shuttle wreckage.
Experts believe it may be significant that the wing was discovered a considerable distance west of where the bulk of the shuttle debris was found.
The find suggests the wing was among the first pieces confirmed to have hit Earth.
"If it’s from the left wing," said Ron Dittemore, the shuttle programme manager, "I think that would be more significant."
Determining whether the wreckage is from the left wing should be a simple task for Nasa. The wing’s leading edge was still attached to 18in of structure that included heat-resistant tiles.
Each tile is marked with a unique code, allowing investigators to pinpoint which part of the shuttle it came from. Nasa has also released a photograph taken from a secret airforce installation in New Mexico, about a minute before contact was lost with the crew.
The picture, taken from a camera in a telescope normally used to test how to photograph satellites, is almost a silhouette of the orbiter.
It appeared to show a slight bulge or deformity along the front edge of the left wing, and plume emanating from the back of the wing that did not match the plume on the right side.
Dittemore said of the picture: "That does look a little different to us, and that’s an area of investigation." But he said it was unclear whether the bulge indicated a jagged break in the wing or a mirage caused by atmospheric distortion.
As a result, he said, he was not persuaded that the photograph would yield significant information about the cause of the disaster.
But he added he was hopeful it would tell investigators something about the state of the vehicle in the final moments before it broke up.
While Dittemore warned against rushing to conclusions, the combination of the photos and the finding of the wing section may, within days, give greater credence to theories that the front or underside of the wing was breached and caused the disaster.
Until now, much of the focus or the investigation has been on foam insulation that broke free from the external tank on liftoff and hit the wing at speed.
Engineers examined the issue and concluded, before the seven-member crew began the descent, that whatever damage had occurred as the foam hit the wing was tolerable.
Now, Dittemore said, they were revisiting that finding, conducting extensive tests to determine whether the judgment was hasty.
The leading edge of the wing is made of 22 pieces of carbon-composite. Their purpose is to handle the enormous heat and stress of re-entry into the atmosphere.
Like the O-rings that failed in the 1986 Challenger shuttle disaster, the carbon-composite and the heat-resistant tiles on the underside of the orbiter are considered elements whose failure could lead to disaster and death.
Dittemore said that Nasa had received 350 reports of shuttle wreckage found outside of the main debris in east Texas and Louisiana - but that none had been confirmed as shuttle parts.
