23 March 2003
23 March 2003
Evidence grew that the mysterious object detected flying off the space shuttle Columbia on its second day in space was a removable maintenance panel cover, and that its loss could have played a role in the disintegration of the spacecraft.
Investigators probing the disaster have theorized that a row of the covers on the underside of the left wing of the shuttle could be the spot where hot gas entered Columbia on re-entry. The panels form a narrow layer between the tough composite material that makes up the wing's front edge and the heat-protection tiles that cover the bulk of the underside of the wing. These covers, called carrier panels, are bolted on and can be removed between flights for maintenance.
The mystery object is ''about the right size'' to be a carrier panel, board member James Hallock said. Results of military radar tests show that the object seen moving off Columbia while it was in orbit wasn't a heat-protective tile or a thermal insulating blanket, he said. ''So it sounds like it's something bigger, and there aren't too many'' other objects it could be, Hallock said.
The object re-entered the atmosphere five days after it came off the shuttle. That's consistent with how a carrier panel would have behaved, Hallock said.
All seven astronauts aboard Columbia died in the accident. Eighty seconds after Columbia lifted off the launchpad Jan. 16, a chunk of debris fell off the shuttle's large exterior fuel tank and smashed into its left wing. Investigators say they believe it hit the front part of the underside of the wing -- exactly where the carrier panels sit.
Asked how the panel could have come loose in space, Hallock told reporters that the first 8 1/2 minutes of a shuttle flight are ''a wild ride. . . . I'm surprised a lot of things don't come loose.''
Board Chairman Harold Gehman said it isn't at all surprising that a piece shaken loose during launch would detach from the vehicle in orbit. ''Astronauts have told me that on day two or day three of a flight, they've looked out the window and seen a washer floating by,'' Gehman said. ''Things happen.''
Investigators have been trying for weeks to determine the precise location where a stream of super-hot air blasted into the shuttle's left wing. The jet of air was so hot that it melted the corner of a piece of hardware made of titanium, which melts at 3,000 degrees. The damage it caused was catastrophic.
If a carrier panel came off the shuttle's left wing, it could have caused the wing to shed more pieces. That could have provided the entry point for the destructive jet of hot air. It's not clear how the loss of a carrier panel on the second day of flight relates to other data about the shuttle's demise.
Wind tunnel tests suggest ''an opening of a fairly large cavity on the lower surface'' could create that lift, NASA's Stephen Labbe said. But NASA engineers don't know which piece or pieces might be responsible. Engineers are testing whether damage to carrier panels and other pieces could account for the lift.