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Columbia's safety margins misread, expert tells panel



Submitted by Arthur - N1ORC with previous permission of the Houston
Chronicle

http://www.chron.com/cs/CDA/ssistory.mpl/space/1836343

March 25, 2003, 9:59PM

Columbia's safety margins misread, expert tells panel

By MARK CARREAU
Copyright 2003 Houston Chronicle
CAPE CANAVERAL, Fla. -- NASA displayed insufficient attention to safety
precautions when it launched Columbia without ensuring it was able to
withstand the impact of fuel tank insulation striking vulnerable sections
of a wing, an expert told investigators on Tuesday. 

Because foam had dislodged on four previous missions and those shuttles
had successfully returned, NASA erroneously assumed Columbia's safety
margins were robust enough, said retired Air Force Lt. Gen. Aloysius
Casey, former director of development for the Pentagon's Peacekeeper
ballistic missile. 

The most recent had occurred in October, when the shuttle Atlantis was
struck by foam that bounced harmlessly off a rocket booster. 

"A series of successful flights does not verify margins," Casey, now a
space systems consultant, told the Columbia Accident Investigation Board.
"You may be skating on the very edge and you may come to that flight
where either the environment or the hardware causes you to go negative." 

Columbia broke up over North Texas on Feb. 1 while re-entering Earth
atmosphere, killing all seven astronauts. 

The cause has not been identified, but investigators are focusing on a
chunk of debris, probably foam insulation from the external fuel tank,
that struck the underside of the left wing after Columbia's Jan. 16
liftoff. Most theories cite a thermal and structural failure triggered by
a breach in the left wing. 

Casey urged investigators to require that NASA re-establish safety
margins for aerodynamic stresses, pressures and temperatures for all
critical subsystems before missions resume, and set new procedures to
ensure the fuel tank foam adheres properly. 

He also recommended that shuttle missions be limited to only those that
merit the risk of using astronauts and that the crew be kept to as few
people as possible. 

Casey was the second expert to appear before the panel to voice concern
with NASA's safety procedures. 

Earlier, Henry McDonald, a former space agency official, testified about
safety practices in 1999 after Columbia experienced a series of
electrical problems and a fuel leak after reaching orbit. The problems
were traced to damaged electrical wiring, as well as an undocumented
procedure for plugging combustion chamber injection ports in the rocket
engines. 

Both men said the agency's safety practices relied so heavily on past
successes they offered a false sense of security that failed to identify
subtle but lurking hazards. 

Tuesday's hearing was the third for the 13-member board chaired by Harold
Gehman, a retired U.S. Navy admiral, and the first sessions outside of
Houston, home of NASA's Johnson Space Center and host to Mission Control.


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