NASA is hoping to launch Space Shuttle Discovery on its final voyage no earlier than Feb. 24, after months of delays due to cracked fuel tank supports, the space agency announced Jan. 11.

Top space shuttle officials announced the new launch target after reviewing ongoing work to repair Discovery’s external fuel tank.

Discovery’s final spaceflight has been delayed since early November due to cracked fuel tank support beams that need repair. The new launch target is three days earlier than previous estimates, which cited a launch window that would begin Feb. 27 and close March 6.

Technicians at NASA’s Kennedy Space Center in Cape Canaveral, Fla., have been adding metal strips to support beams, known as stringers, in the tank’s so-called intertank region. Initially, 32 stringers in the regions that undergo the most stress during the shuttle’s launch and ascent were modified, but shuttle program managers have since decided to expand the work to reinforce 95 of the support beams.

Shuttle program managers also met Jan. 10 to discuss the status of repairs, and they updated the media in a press conference the following day.

Meanwhile, the astronauts who will fly aboard Discovery on its 39th and final mission will spend the extra time practicing contingency abort scenarios at the Johnson Space Center in Houston, the training base for shuttle crews and the home of the Mission Control Center.

Discovery’s last mission will deliver critical spare parts to the station, as well as a storage room module and a humanoid robot to assist the crew of the orbiting laboratory.

The flight is one of the last two scheduled missions as NASA prepares to retire its three-orbiter fleet in 2011. NASA also plans to fly a third flight around midyear pending final funding approval from Congress.

In addition to Discovery’s flight, NASA’s shuttle Endeavour is slated to launch April 19 on the STS-134 mission to deliver an astrophysics experiment to the space station. That mission is currently slated to be commanded by astronaut Mark Kelly, whose wife — U.S. Rep. Gabrielle Giffords (D-Ariz.) — is recovering from a gunshot wound to the head after a Jan. 8 attack in Tucson, Ariz., that killed six people and wounded 13 others, including Giffords.

NASA said Jan. 13 that astronaut Rick Sturckow would serve as backup commander for the STS-134 mission to facilitate training for the crew and support teams during Kelly’s absence.

“I recommended to my management that we take steps now to prepare to complete the mission in my absence, if necessary,” Kelly said in a statement. “I am very hopeful that I will be in a position to rejoin my STS-134 crew members to finish our training.”