Probe Close to Locating Shuttle Breach

After analyzing shuttle debris and new data from sensors aboard the Columbia during its ill-fated return to Earth on Feb. 1, investigators say they can now almost pinpoint where superheated gases entered the space shuttle’s left wing.

“We are within 30 inches of knowing where the actual breach occurred,” Roger Tetrault, a member of the Columbia Accident Investigation Board, said Tuesday.

Although the location of the breach is becoming clearer, the investigators are not quite sure what part of the leading edge of the wing contained the gap or hole. It could be a leading edge panel, which is a u-shaped structure that forms the forward curvature of the wing, or a t-seal, which insulates the gaps between the leading edge panels.

Tetrault said investigators believe the gap occurred at leading edge panel eight or its adjacent t-seal, both of which are slightly closer to the fuselage than originally thought.

The revision follows detailed analysis of the sequence in which sensors on the wing failed and the associated wires that melted as the 3,000-degree gases entered into the wing. Minutes later, the failure of the thermal protection system caused the shuttle to break up over Texas.

At the same time, investigators are pressing ahead with their analysis of a mysterious object spotted on the second day of the Columbia mission from ground radar. The object was observed floating nearby the shuttle and orbiting Earth along with the orbiter.

Based on its observed size and radar characteristics, investigators are growing confident that the mysterious object is a missing part of the wing. Tetrault said that foam striking the wing shortly after launch remains the leading explanation of how the wing was damaged.

The investigators are awaiting foam tests that will begin Thursday at the Southwest Research Institute in Texas. The institute will use a gas-powered gun to fire foam chunks at shuttle parts.

The tests will begin with heat tiles from a landing gear door, though that location no longer figures prominently in the technical investigation.

By next month, investigators hope to refine a plan to fire foam at leading edge panels, constructed of delicate reinforced carbon carbon to assess the vulnerability of the Columbia wing, board Chairman Harold W. Gehman Jr. said.