Shuttle Cracks Baffle NASA

By Mark Carreau

HOUSTON — Though nearing a 2011 retirement, NASA’s shuttle program has not lost a penchant for throwing a curve ball — this time a collection of cracks on a region of Discovery’s external fuel tank that separates internal oxygen and hydrogen propellant containers.

The mystery over the underlying cause of the four cracks in adjacent “intertank” stringers has had Discovery’s final ...

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