Kalpana’s remains identified: NASA

Meanwhile, investigators said that a devastating puncture that allowed hot air inside space shuttle Columbia’s left wing may be the reason behind its disintegration on February 1, that killed Kalpana Chawla and six other astronauts.

Investigators said Columbia broke up during re-entry, possibly because of the presence of super-heated air or plasma inside the left wing.

The new theory for the shuttle’s disintegration rules out the loss of heat resistant tiles as was initially put forth as a possible cause for the disaster.

‘‘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,’’ NASA spokesman James Hartsfield said.

Moments before Columbia disintegrated, mission control in Houston detected an unusually high heat build-up in the left wing, which could have indicated missing or damaged tiles.

The board also dismissed suggestions on the shuttle’s left landing gear being improperly lowered as it made its re-entry into the atmosphere. Earlier, the space agency had revealed that a sensor indicated the gear was down just 26 seconds before Columbia’s destruction. The landing gear is to be lowered when the shuttle is about 200 feet over the runway and flying at 555kmph.

Experts say the shuttle could have disintegrated quickly if the landing gear had been lowered at a height of 64 km during its descent at over 20,000kmph.