Tests have revealed that an object spotted falling from the space shuttle Columbia on the second day of its doomed mission was a panel of protective heat-resistant tiles.
The absence of this panel would have provided a point of entry in the shuttle鈥檚 left wing for the superhot gases that investigators believe got inside the craft during re-entry. The plasma melted the shuttle鈥檚 aluminium frame and caused the craft to disintegrate, with the loss of all seven astronauts aboard.
Radar pictures revealed the object falling from the shuttle as it performed a pivotal manoeuvre in orbit for a scientific experiment. Investigators have now taken radar images of various shuttle components to try to find a match.
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鈥淥nly the carrier panel remains a viable candidate for the day two object,鈥� said Air Force Major General John Barry, a member of the Columbia Accident Investigation Board (CAIB), on Tuesday.
Chain of events
This latest development in the investigation permits an entire chain of events to be provisionally constructed. Video footage of Columbia鈥檚 launch shows the left wing being struck by a piece of foam from an external fuel tank. This may have caused critical damage to the protective tiling.
Barry said the carrier panel could have remained in place during lift off because of the pressure of passing air. Once in orbit, the panel fell off and the shuttle鈥檚 fate was sealed.
However, Roger Tetrault, another CAIB member, cautioned against rushing to a conclusion and prematurely ruling out other explanations for the object. 鈥淵ou can鈥檛 make this leap of faith,鈥� he said. The investigators plan more tests in which foam samples are fired at a space shuttle wing to better understand the damage this could have caused.
The carrier panel is located between panels on the wing鈥檚 leading edge and on the flat underside of the wing. It forms a smooth surface that protects the shuttle鈥檚 wing from the extreme heat generated during re-entry into the Earth鈥檚 atmosphere.
Paint primer
Investigators also said on Tuesday that they are examining the extent to which paint primer from the shuttle鈥檚 launch pad support structure may have corroded the reinforced carbon wing tiles prior to launch.
The primer is known to cause small holes in the protective material, and investigators believe this may have exacerbated the damage sustained during launch.
Finally, CAIB said that early analysis of the magnetic tape recovered from an experimental data recorder shows that it stored information from nearly all 721 shuttle sensors connected to it. The tape鈥檚 data has already revealed that extreme heating in Columbia鈥檚 left wing occurred much earlier than previously indicated.