Space Shuttle Discovery Repaired for Final Voyage

NASA's space shuttle Discovery is all patched up for its planned final launch into space next week, NASA officials said today (Nov. 22).

Engineers have completed work to plug a potentially dangerous hydrogen gas leak and reinforce cracked metal ribs on Discovery's huge external tank. The shuttle is sitting atop a seaside launch pad at NASA's Kennedy Space Center in Cape Canaveral, Fla., awaiting a launch that has already been delayed more than a month.

Discovery's upcoming launch is currently slated for no earlier than Dec. 3 at 2:52 a.m. EST (0753 GMT).

Two cracks each were found on two metal ribs, called stringers, around the upper middle portion of Discovery's external tank. On Friday (Nov. 19), shuttle technicians installed new sections of double-thick metal to replace the cracked areas. [INFOGRAPHIC: NASA's Space Shuttle ? From Top to Bottom]

"The stringer cracks were repaired last week and foam was reapplied during the weekend," NASA spokesman Allard Beutel told SPACE.com in an e-mail.

A separate crack in the exterior foam insulation on Discovery's fuel tank was also repaired. Workers are now trimming the foam to achieve ideal aerodynamic shape and doing additional X-ray scans to ensure there are no other potential problems.

So far, no other issues have been detected, and "they're pretty much done with the overall repair work," Beutel said.

On Wednesday (Nov. 24), shuttle program managers will analyze their rationale for flying Discovery with the completed repairs. If the officials are satisfied and agree that the shuttle is ready for its mission, NASA will proceed with a final review on Nov. 29 to clear Discovery for liftoff.

Discovery's STS-133 mission will be the shuttle's 39th and final flight, before it is retired along with the rest of NASA's orbiter fleet in 2011.

The expedition will send commander Steve Lindsey, pilot Eric Boe, and mission specialists Alvin Drew, Tim Kopra, Michael Barratt and Nicole Stott to the International Space Station on an 11-day mission. The spaceflyers will deliver a storage room for the orbiting laboratory, in addition to a humanoid robot designed to assist astronauts with their work in space. Drew and Kopra are also scheduled to perform two spacewalks.

The upcoming window to launch Discovery opens on Nov. 30 and will close around Dec. 6. NASA's shuttle Endeavour is scheduled to fly to the space station in the next available window, which opens in late February.?

NASA is retiring the space shuttle fleet as part of its new direction, which aims to send astronauts to an asteroid by 2025, and ultimately to Mars in the 2030s.

After Discovery's flight, there is only one more scheduled mission, a flight by shuttle Endeavour to the space station. NASA, however, is hoping to obtain final funding approval for a third shuttle mission, which would fly no earlier than June 2011.

Congress and President Obama have authorized plans for the extra shuttle mission, but the measure is still awaiting a final congressional appropriations review.

• Gallery: Building Space Shuttle Discovery
• Video ? Space Shuttle Discovery: A Retrospective, Part 2, Part 3
• Space Shuttle Discovery's Retirement Plan in Limbo