The storm hurled golf-ball-size hail at the launch pad Monday afternoon, leaving hundreds of small dings on the some 50-meter-tall external fuel tank. It also caused cosmetic damage to more than two dozen tiles along the shuttle's left wing.

    Workers at the Kennedy Space Center in Florida are still assessing the extent of the damage, but NASA managers decided Atlantis must be rolled back to the Vehicle Assembly Building for thorough inspections and repairs, which means the launch would be pushed back to at least late April.

    As planned, the shuttle will be moved to a giant hangar as early as this weekend. NASA technicians will decide whether repairs can be made at the Kennedy Space Center or whether the tank needs to be returned after the results of the review comes out.

    NASA personnel are extremely cautious regarding any damage to a shuttle's external tank or heat shield.

    In 2003, foam flew off space shuttle Columbia during liftoff in 2003 and struck the orbiter. The damage allowed fiery gases to penetrate Columbia during re-entry, breaking up the craft and killing its seven astronauts.

    (Agencies)