Sensors the first sign of trouble

From correspondents in Houston, Texas
February 02, 2003

THE first indication of trouble on shuttle Columbia was a loss of temperature sensors in hydraulic system of left wing, a NASA official said today.

Space Center Houston worker Nury Serling reacts to the tragedy.
Cause: No clue in last contact
Warning: Wing struck at takeoff
Investigation: NASA inquiry
Reaction: Bush calls families

The crew of Columbia pointed out technical difficulties in the seconds before the space shuttle disintegrated over Texas as it re-entered the Earth's atmosphere.

Ron Dittemore, the shuttle program manager, said that during Columbia's liftoff, a piece of insulating foam from the fuel tank was believed to have hit the left wing.

Dittemore said the loss of the sensors on the left wing was followed seconds later by several other problems, including a loss of tyre pressure and indications of excessive structural heating.

"Our thoughts and our prayers go out to the families of Rick and Willie and Davie and Kalpana, Michael and Larel and Ilan. True heroes," he said.

It was possible that debris that struck the left wing of Columbia during takeoff may have played a role in the space shuttle's breakup, Dittemore said.

"And so as we look at that now in hindsight, that impact was on the left wing," he said.

"We can't discount that there might be a connection."

Dittemore said videos of the takeoff showed foam break free of the craft and appear to strike the shuttle's wing.

"We spent a goodly amount of time reviewing that film and then analysing what that potential impact of debris on the wing might do and would there be any consequences... it was judged that that event did not represent a safety concern," he said.

"We can't discount that there might be a connection.

"But we have to caution you and ourselves that we can't rush to judgment on it because there are a lot of things in this business that look like the smoking gun but turn out not even to be close."

Is it possible that missing heat shields near the wheel bay could have caused heat build up in that area to a point where the tyre could have caught fire?

View the sequence of the events below:

20 to 30 degree rise in temperature in left wheel well over 5 minutes.

08:54 (Eastern California & Western Nevada)
Mid-fuselage bond line (bond between fuselage and top of wing on the port side) has a 60+ degree temperature rise over 5 minutes. Starboard side is nominal at 15+. Inside of the Orbiter's fuselage wall, the temperature is nominal.

8:56 a.m.
Sensors detect rise in temperature and pressure in tires on the shuttle's left-side landing gear.

8:58 a.m.
Data is lost from three temperature sensors embedded in the shuttle's left wing.

I would guess that the rubber tyre had caught fire, soon followed by the hydraulic fluid.

Flight Control problems noted may have been caused by the left main-gear door then opening.


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