An inquiry board recommended the repair to prevent pieces of insulating foam breaking away from the skin of the tanks and striking the shuttle itself, which was the apparent cause of the February 1, 2003 breakup of the shuttle Columbia.

Lockheed Martin crews fixed the fuel tank over the past 18 months at NASA's Michoud assembly facility near New Orleans, Louisiana. The repair is an important step toward restoring space flights next year.

The enormous tank will be dispatched to NASA's Kennedy Space Center in Florida, NASA project director Sandy Coleman told journalists.

The inquiry board found that a piece of dislodged insulating foam hit the left wing of the Columbia hard enough to damage the craft's protective, thermal skin.

On reentry, superheated gasses entered the wing and destroyed its internal structure, triggering the craft's destruction.

The foam prevents the formation of ice on the outside of the super-cooled liquid oxygen and hydrogen tanks.

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