Wing breached 3 times

http://www.floridatoday.com/columbia...ory2A5346A.htm

Hallerb wrote in message
...
http://www.floridatoday.com/columbia...ory2A5346A.htm

I saw that this morning and to be honest, it made me a bit sick to my
stomach. I'm not ready to become a NASA-basher yet, but Jesus what were
they thinking.
end emotional response to an engineering problem

I saw that this morning and to be honest, it made me a bit sick to my
stomach. I'm not ready to become a NASA-basher yet, but Jesus what were
they thinking.
end emotional response to an engineering problem


A Florida Today review of mission and runway inspection reports as well as
separate NASA problem reports, many of which the newspaper obtained under the
Freedom of Information Act, showed that damage to the leading edge of the
shuttles' wings is not uncommon or new.

The three previous breaches are significant.

The composite carbon panels encounter temperatures as high as 3,000 degrees
Fahrenheit during atmospheric re-entry. A penetration of hot gases,
consequently, can lead to the loss of a $2 billion shuttle and its astronaut
crew.

The problem dates back to the early days of the shuttle program.

On NASA's second shuttle flight in November 1981, hot gases blasted past
Columbia's wing panels near a spot where they join with heat-shield tiles on
the underside of the orbiter, according to a mission report.

The searing heat scorched and burned through a fiber barrier used to fill gaps
between heat-shield components. The gases streaked an aluminum spar inside one
of wing, the report says.

NASA subsequently modified the thermal barrier and saw less damage on the next
flight.

A similar problem, however, cropped up again on NASA's fifth shuttle flight in
November 1982 -- another Columbia mission.

A jet of hot gas melted a small hole in a tile-covered metal bar connected to a
wing panel. It damaged internal insulation but none of the metal components
inside the wing, a mission report says.

No damage was noted on the next flight.

A more recent incident came at the end of a May 2000 Atlantis mission to the
International Space Station. On that flight, hot gases penetrated a dislodged
seal between two panels on the shuttle's left wing.

A subsequent investigation showed the seal had been installed improperly during
a shuttle overhaul, creating a quarter-inch gap that served as a "substantial
flow path" for hot gases, a NASA document says.

Charred and scorched as a result: Internal components made of Inconel and
titanium – metals that have melting points between 2,500 and 3,000 degrees,
respectively.

The damage was repaired and NASA ordered changes in the way that seals between
wing panels are installed.

Less threatening but still significant damage has been more common.

Micrometeoroids and launch debris strikes dented or cracked wing panels on at
least nine missions between April 1991 and March 2001, NASA records show.

Wing panels also have been damaged by exposure to extreme temperatures and
pressures encountered during flight. And zinc primer leaching off the launch
tower has corroded them.

The lesser damage has ranged from small pits to larger cracks.

Investigators have raised concerns about whether the panels weaken with age
too. Only three of Columbia's panels were replaced during its 22 years of
flight.

Investigators, meanwhile, think even a relatively small crack in a wing panel
could doom a shuttle crew. The damage done to Columbia, however, likely was
more dramatic.

I