The U.S. space agency has delayed the next space shuttle mission until March 2006, ruling out the launch originally planned for September.
NASA officials are still trying to determine why a large piece of hard foam broke off from the shuttle Discovery's fuel tank during launch last month.
A similar piece of foam damaged the shuttle Columbia on liftoff and led to its break-up on re-entry in 2003.
The delay comes one day after a group of seven experts said NASA officials have compromised safety to ensure the space shuttle's return to flight.
The experts were dissenting from the report of a larger task force evaluating safety procedures in the shuttle program.
The full 25-member task force said NASA has made significant strides to correct the conditions that led to the Columbia disaster.