Preliminary analysis by a NASA working group this week indicates that the temperature indications seen in Columbia's left wheel well during entry would require the presence of plasma (super heated gas surrounding the orbiter during re- entry).

Heat transfer through the structure as from a missing tile would not be sufficient to cause the temperature indications seen in the last minutes of flight.

Additional analysis is underway, looking at various scenarios in which a breach of some type, allowing plasma into the wheel well area or elsewhere in the wing, could occur.

Other flight data including gear position indicators and drag information does not support the scenario of an early deployment of the left gear.

The search continues for possible debris from Columbia in the western U.S., but as of early Thursday, no debris further west than Ft. Worth, Texas has been confirmed as Shuttle- related.