The next space shuttle flight will blast off no earlier than March

The six-month delay will give engineers more time to fix the persistent problem of debris falling from the shuttle's fuel tank. The delay will also make it easier for NASA to juggle its three shuttles to make sure Atlantis is available to fly a large piece of the International Space Station to orbit next year.

But the delay puts further pressure on NASA chief Michael Griffin's hopes of finishing construction of the space station by 2010, the shuttle's target retirement date. Only the shuttle is big and powerful enough to haul the station's components to orbit. Shuttle Columbia disintegrated in 2003 after foam debris from its fuel tank inflicted fatal damage to the wing. Despite NASA's efforts to solve the problem, debris also fell off shuttle Discovery's tank during its July 26 launch. The debris did not hit the shuttle. The ship landed safely Aug. 9.

The extra time in the schedule allows NASA to ship several fuel tanks back to the Michoud factory, outside New Orleans. There, technicians plan to slice and dice the foam on some of the tanks as they try to figure out why certain pieces of foam broke free and how to stop that from happening in the future, USA Today reports.