Cold weather delays Discovery's rollover to VAB

As Endeavour's crew begins its work on the International Space Station, Kennedy Space Center crews are working hard to prepare the next shuttle flight.

Discovery is expected to be moved into the Vehicle Assembly Building on Friday morning, a day later than planned because cold temperatures expected Thursday could harm the spaceship.

The orbiter can't be exposed to temperatures below 45 degrees for more than four hours, and no purging of warm air is available during the procedure known as "rollover."

The move from the hangar to the 52-story assembly building only takes about 30 to 45minutes, but it then takes hours to lift the orbiter into a high bay for attachment to an external tank and twin solid rocket boosters on a mobile launch platform.

Managers will convene at 7 a.m. Friday to determine if it's OK to proceed with the rollover.

The delay pushes back by one day the planned rollout of the assembled shuttle to Feb. 19 -- the day before Endeavour is scheduled to land at KSC -- but NASA says there's no impact to the mission's targeted March 18 launch date.

Here's a look at the key milestones ahead for the 131st shuttle mission, one of four remaining after Endeavour's return:

-- Feb. 11: Discovery rolled from Orbiter Processing Facility No. 3 to the assembly building atop a 76-wheeled transporter.

-- Feb. 19: The giant crawler-transporter carries the shuttle stack from the assembly building to launch pad 39A.

-- Feb. 22-24: Discovery's crew of seven astronauts, led by commander Alan Poindexter, arrives at KSC for three days of training called the Terminal Countdown Demonstration Test. Also on the crew are pilot Jim Dutton and mission specialists Clay Anderson, Rick Mastracchio, Dorothy Metcalf-Lindenburger, Stephanie Wilson and Naoko Yamazaki of the Japan Aerospace Exploration Agency. This is the last planned seven-person shuttle crew; the other three missions have crews of six.

-- Feb. 24-25: Shuttle program managers hold a flight readiness review and recommend a launch date to forward to the agency executive-level review.

-- March 1: Johnson Space Center in Houston hosts a series of preflight media briefings including shuttle and space station program managers, Discovery mission managers, spacewalk planners and the astronauts. (Later the same evening, a Delta IV rocket carrying a weather satellite is scheduled to blast off from Cape Canaveral.)

-- March 2: The mission's primary payload, the Italian-built cargo carrier named Leonardo, is to be delivered to launch pad 39A.

-- March 11: NASA executives meet at Kennedy Space Center for a final flight readiness review to confirm Discovery's launch date. A news conference will follow the meeting.

-- March 18: The current target liftoff date for Discovery's 13-day space station supply run.

IMAGE NOTE: In Orbiter Processing Facility 3 at Kennedy Space Center on Jan. 8, members of shuttle Discovery's STS-131 crew participate in training activities during the Crew Equipment Interface Test, or CEIT, for their mission. Above, buckets are used to move the crew members through Discovery's payload bay without damaging the bay's lining. Below, mission commander Alan Poindexter inspects the windows in Discovery's cockpit from inside the crew module. The CEIT provides the crew with hands-on training and observation of shuttle and flight hardware. The seven-member crew will deliver the multi-purpose logistics module Leonardo, filled with resupply stowage platforms and racks to be transferred to locations around the International Space Station. Three spacewalks will include work to attach a spare ammonia tank assembly to the station's exterior and return a European experiment from outside the station's Columbus module. Photo credit: NASA/Kim Shiflett.