GRAHAM WARWICK / WASHINGTON DC
Move to avoid repeat of criticism of 1986 Challenger inquiry
The independent Columbia Accident Investigation Board has taken charge of the probe into the break up of the Space Shuttle orbiter during re-entry on 1 February.
Before the board began work at NASA's Johnson Space Center on 6 February, its charter was clarified to "absolutely guarantee" its independence and avoid the criticism of NASA's investigation of the 1986 Challenger explosion.
The board, led by retired US Navy admiral Hal Gehman, is charged with determining the causes and consequences of the Columbia accident, in which all seven astronauts on board were killed.
"The board's findings are what we will be guided by," says NASA administrator Sean O'Keefe. "There will be no competing opinions. That is the hard, hard legacy - the lesson learned - of the post-Challenger experience."
As Flight International went to press, NASA was playing down the possibility that external-tank foam insulation shed during launch on 16 January could have damaged thermal-protection tiles on the underside of Columbia's left wing seriously enough to allow a thermal breach during re-entry.
A US Air Force tracking camera at Kirtland AFB, New Mexico, captured footage of Columbia as it flew over the south-west USA about 1min before the break-up, but NASA was last week unable to confirm reports suggesting the photographs show structural damage to the leading edge of the vehicle's left wing.
Investigators are mapping the timeline of temperature readings and sensor failures on the left wing in an effort to backtrack to the heat source.
Similar reverse analysis is under way on the flight-control data, to find out why Columbia's autopilot was "fighting a losing battle" with increasing drag on the left side of the vehicle.
By late last week, despite witness reports of debris being shed by Columbia as it crossed California, no confirmed debris had been located west of Fort Worth, Texas, says Space Shuttle programme manager Ron Dittemore. The main debris field stretches from Fort Worth east into Louisiana.
"Fault trees" for both the orbiter and external tank are being identified. "We will examine every potential cause, however remote, and systematically close each branch of the tree," says Dittemore.
Source: Flight International
