March 6, 2003. Copyright, 2003, Graphic News. All rights reserved

Search for Ògolden nuggetÓ to explain disaster
By Joanna Griffin

LONDON, March 6, Graphic News:  Somewhere among the thousands of shards of charred and twisted metal assembled at a Florida space hangar, experts hope, lies the vital clue as to why the Columbia space shuttle disintegrated as it came in to land on February 1, killing seven astronauts.

Around 300 workers have helped to recover more than 11 tons of debris that scattered over at least two states when the Columbia blew up as it re-entered the EarthÕs atmosphere over Texas, just 16 minutes before touchdown. Resembling a giant puzzle, the debris has been sorted on a 50,000 square foot (4,650 square metre) grid marked by blue and yellow tape at a hangar of the Kennedy Space Centre.

Top among theories being considered by the Columbia Accident Investigation Board is the possibility that a 2lb (1kg), 20-inch (50cm) piece of foam insulation from the shuttleÕs fuel tank fell off during take-off on January 16 and hit the left underside of the wing, causing damage to the fragile thermal tiles that protect the shuttle against the heat caused by the friction of re-entry.

So far, almost 20,000 pieces of debris have been recovered, and telemetry has enabled experts to determine that searing plasma -- air heated to 2,500 degrees Fahrenheit (1,370 degrees Celsius) -- somehow penetrated the left wing. But investigators led by retired Navy Admiral Hal Gehman are still searching for what he has called the Ògolden nuggetÓ to explain the sequence of events.
 
They may never find it. Unlike an airplane, a space shuttle does not have a Òblack boxÓ to record flight details. The sheer speed of the ColumbiaÕs re-entry -- it was travelling at 12,000mph (19,300k/ph) -- means that many of its components will have vaporised instantly. To date workers have found just 13% of the total shuttle, considerably less than the amount that was eventually needed to piece together the causes of the Challenger disaster in 1986.

Enquiries of this scale are routinely dogged by controversy, but Nasa has found it particularly hard to deflect criticism over an exchange of emails by engineers that anticipated problems with the left wing. It has been pointed out that concerns about the foam and tiles are not new: the shuttle was damaged by a piece of flyaway foam during a 1997 mission. For all these reasons it may be some time before the remains of the Columbia reach their final resting place.
/ENDS