This story has been updated at 4:15 p.m. EST.
NASA's latest launch delay for the space shuttle Discovery could push the spacecraft's final mission into the Christmas holiday, or even postpone it completely until February, agency officials said Wednesday.
Top shuttle program managers met today (Nov. 24) to review recent repairs to Discovery's massive external fuel tank. Based on the discussion, NASA officials decided to forgo any launch attempts until at least Dec. 17, if not into the next launch window in February.
"What we've told the agency leadership is that clearly we're not ready for the Dec. 3 to Dec. 7 window that's coming up next week," John Shannon, NASA's shuttle program manager, said in a news conference this afternoon. "We'll leave the option open for a launch window for Dec. 17, but a lot of data has to come together to support that."
A mid-December launch would push Discovery's planned 11-day spaceflight into the Christmas holiday, something NASA has typically worked to avoid. The agency tries to not schedule any shuttle flights over the Christmas and New Year's holidays, because shuttles in orbit during the year change would need a flight computer reconfiguration, shuttle managers have said.
If NASA is unable to launch Discovery in December, the next clear chance to do so would come in February.
Shannon added that the engineering teams are concerned primarily with understanding the issues and evaluating the risks, and are less concerned with setting any definite launch dates.
"We want to make sure we fully understand the problem before we fully commit to go fly," Shannon said.
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.
Month of delays
The final flight of Discovery has already been delayed by over a month due to technical and weather-related issues. As it stands, the mid-December launch window opens on Dec. 17 and runs through Dec. 20. A Dec. 17 launch, if approved, would occur at 8:51 p.m. EST (0151 Dec. 18 GMT), NASA officials said.
Most recently, Discovery was slated to launch with a six-astronaut crew on Dec. 3 at 2:52 a.m. EST (0753 GMT) from a seaside launch pad at NASA's Kennedy Space Center in Cape Canaveral, Fla. The shuttle's planned 11-day mission will deliver a storage room and Robonaut 2, a humanoid robot, to the International Space Station. Two spacewalks are also planned.
In the last week, engineers completed work to plug a potentially dangerous hydrogen gas leak and reinforce cracked metal ribs on Discovery's huge external tank. Still, shuttle program managers did not feel they had a firm enough grasp of how the problem originated in order to proceed with a launch attempt next week.
Two cracks each were found on two metal ribs 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.
A separate crack in the exterior foam insulation on Discovery's fuel tank was also repaired, NASA officials said.
"Even though the problem may be fixed, you make sure, generically, that you're not exposed to that same risk anywhere else," Shannon said. "We need to nail down our risk exposure to this."
Discovery's launch options
If NASA is unable to make the mid-December launch window, Discovery's STS-133 mission could be pushed into late February, when the next window opens up.
Teams at Kennedy Space Center have been hard at work since Discovery's launch was originally scrubbed on Nov. 5.
Workers have been given Thursday and Friday off ? for the Thanksgiving holiday in the United States ? with work expected to resume on Saturday.
Managers will meet again on Dec. 2 to assess progress toward the Dec. 17 launch opportunity.
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You can follow SPACE.com Staff Writer Denise Chow on Twitter @denisechow.