The space shuttle Discovery may launch as soon as Feb. 24, following repairs to the brackets on its fuel tank.

The shuttle is scheduled to blast off as soon as 4:50 p.m. ET that day, NASA announced Tuesday at a news conference detailing the cause of the problem that forced it to postpone a launch that had been set for early November.

The brittleness of the materials used in making some of the U-shaped brackets, called stringers, on the shuttle's external fuel tank are partly to blame, said John Shannon, NASA's space shuttle program manager, at a news conference Tuesday.

That, combined with the stresses applied to the stringers when they were assembled with the fuel tank, led to the formation of cracks on two of the brackets discovered ahead of the November launch.

To fix the problem, NASA will place blocks over the feet of the stringers, allowing them to handle a load 3.5 to four times greater.

On Tuesday, the shuttle was at the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, NASA reported.

Technicians removed the foam on Discovery's external fuel tank so support can be added to 95 aluminum stringers.

The shuttle was originally scheduled to blast off in October but has been delayed several times. NASA announced last Friday that the shuttle is tentatively set to launch at the end of February, possibly a few days before the official launch window opens on Feb. 27.

The next mission, which will carry a new module and spare components to the space station, is Discovery's last before its retirement, along with the rest of NASA's shuttle fleet.

The space shuttle Endeavour is scheduled to make its final flight in April. The commander for that mission is Mark Kelly, whose wife, Democratic congresswoman Gabrielle Giffords, was critically injured on Saturday by a gunman accused of killing six people and injuring 14 during a shooting spree in Tucson, Ariz.

The Endeavour's flight may be the last of NASA's 30-year shuttle program. However, the shuttle Atlantis may make one additional flight later in 2011.