Shuttle seal likely cause of disaster

Published on Wednesday 7 May 2003 01:00

THE Columbia space shuttle disaster was probably caused by a seal that broke between protective tiles on the left wing, according to preliminary results of an official US inquiry.

The findings have confirmed earlier indications that a piece of insulation foam which hit the shuttle’s left wing during the lift-off had seriously damaged it.

Columbia disintegrated on re-entry into the Earth’s atmosphere on February 1 killing all seven of its crew because hot gases entered a hole in the left wing, according to the Columbia Accident Investigation Board.

The preliminary findings suggest that the piece of foam broke off the shuttle’s fuel tank and hit the left wing 81 seconds after the launch.

The result was that a so-called T-seal - protecting the gap between heat resistant carbon panels on the leading edge - was broken.

"The orbiter re-entered with a pre-existing flaw in its left wing and that flaw was small enough that it made it all the way to Texas, but it was big enough that it allowed hot gases to get into the wing," said retired admiral Harold Gehman, who is heading the investigation.

Although the US space agency Nasa admitted this scenario was the likely cause of the tragedy, the investigators said their findings were only a "working hypothesis".

The investigators said sensors inside the wing detected rising temperatures within five minutes after the craft began its descent.

Within six minutes, the sensors stopped sending data, suggesting wires were melting.

In 15 minutes, all communication with Columbia ceased.

The investigators will now carry out tests to see what happens when chunks of foam are fired at panels of the actual shuttle structure.

The investigation will not be completed for several months, and the shuttle programme will remain grounded until then Mr Gehman said he hoped to be able to make a broad range of recommendations this summer to make the shuttle programme safer.