SPACE CENTER, Houston -- A piece of a thermal tile remains the westernmost debris from Columbia - and probably the earliest known fragment from its breakup - but it has no identifying mark and NASA is struggling to determine where it came from on the shuttle.
The tile was found in West Texas, more than 330 miles west of Dallas. So far, none of the scraps discovered in the Nevada desert are from the shuttle.
The Federal Aviation Administration's Laura Brown, who is serving as a spokeswoman for the Columbia accident investigation board, said Tuesday the serial number on the tile found near Littlefield, Texas, was obliterated. Shuttle technicians are trying to determine what part of the ship it's from by its thickness and shape.
Both NASA and the investigation board believe any wreckage west of Texas could provide hard evidence about what was happening to Columbia as it descended on its way to a Florida landing on Feb. 1. The shuttle was 16 minutes away from touchdown when it disintegrated over Texas, killing all seven astronauts.
The 10-member investigation board, led by retired Navy Adm. Harold Gehman Jr., suspects the left wing was breached, allowing superheated gases to penetrate during re-entry. A central focus of the investigation is whether any of the debris from liftoff 16 days earlier caused or contributed to that breach.
Launch video spotted three pieces of debris from Columbia's external fuel tank, not just one as had been widely reported. At least two of those insulating sections hit the left wing, according to NASA.
NASA spokesman James Hartsfield said engineers do not know whether one piece of hardened foam insulation came off the fuel tank and then broke into three pieces, or whether three separate pieces simultaneously peeled off the same area, a shuttle attach point.
While Columbia was still in orbit, NASA and Boeing engineers concluded that any damage to the thermal tiles from the debris posed no safety hazard.
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