Using the new data, the researchers said the first sign of trouble began when a fracture formed in the left wing's main landing gear and its temperature suddenly rose.
Data collected from a Columbia data collection device found about two weeks ago in Texas shows that the trouble began over a minute earlier than previously thought.
Hot gas penetrated the leading edge of the left wing within 16 seconds of the moment Columbia experienced maximum warming as a result of its entry into the atmosphere.
Examining the new information, one of the accident investigators said that the data shows that Columbia began the descent when the failure mechanism was already in action. The data is from the OEX data recorder, which is in the field in Texas on March 19th.
The OEX is under the crew floor on the mid deck. It records the last 54 minutes of the flight, collecting data from 721 sensors scattered all over the shuttle. Although the device was damaged, the engineers were able to recover data from the magnetic film, which is about 3 kilometers long.
Until the OEX data was read, engineers participating in the investigative committee had only real-time telemetry data to help them diagnose the cause of the Columbia breakup on February 1. Columbia reached the area of maximum aerodynamic pressure at 8:50:53 EST on that fateful Saturday.
Using the new data, researchers said the first sign of trouble began when a fracture formed in the left wing's main landing gear and its temperature suddenly rose. Ten minutes later Columbia disbanded.
Following the first signs of trouble, a series of temperature sensors stopped working due to a plume of extremely hot air making its way into the left wing.
The temperature sensors beyond the leading edge of the left wing, just behind the point where the problem is believed to have started also showed a rapid rise in temperature before disappearing.
From all available evidence, accident investigators believe that the disaster began below the sixth panel of the forward edge of the left wing. Analysis of the 721 sensor readings recorded by the OEX has already begun and engineers will meet to decide how to proceed.
