Cape Canaveral, Fla. ? NASA plans to launch three space-shuttle flights in 2006 if engineers can solve the ongoing problem of dangerous debris falling from the ship’s external fuel tank during liftoff.

Shuttle managers plan to meet Thursday to discuss target launch dates of May 10, Aug. 28 and Nov. 16. Before the first mission flies, however, they must convince themselves that six changes made to the 15-story tank since Discovery’s liftoff last July are safe.

During Discovery’s launch, 16 major pieces of foam insulation, including a large part of a ramp near the tank’s midsection, broke off.

Discovery’s tank is scheduled to arrive by barge at the Kennedy Space Center today. Whether the shuttle launches in May or is postponed until July hinges on engineering tests that will determine whether the tank is safe to fly with the changes.