Landing flight director for the mission, Norm Knight, said the weather forecast for Thursday morning and afternoon is for low clouds and possible thunderstorms. A front located in the panhandle of Florida is likely to cause overcast and rainy conditions at KSC for both Thursday and Friday.

Either condition, low clouds or thunderstorms, would prevent the Shuttle from landing at the Kennedy Space Center in Florida.

The Shuttle and its crew can stay up in space until Sunday, based on the availability of fuel, if the need arises.

If Atlantis cannot land on Thursday, NASA officials will consider landing it at Edwards Air Force Base in California on Friday. The other backup site near Las Cruces, New Mexico, the White Sands Test Facility, is also a possibility on Saturday.

However, any landing site other than at Florida, will likely cause more delays in future missions—something NASA does not want to do unless absolutely necessary.

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