The final planned space shuttle mission, currently slated for mid-November at the earliest, may not lift off until February 2011, according to a NASA spokesperson.

Only two launches remain before the shuttle program's planned phaseout; the next launch, the STS-133 mission of space shuttle Discovery, is currently scheduled for September 16. But a delay in payload hardware for Discovery's mission may force a postponement of STS-133 to October 29, says public affairs officer Michael Curie of NASA Headquarters in Washington, D.C.

That would in turn push back the successive and final shuttle launch, the STS-134 mission of space shuttle Endeavour, to February 28, 2011. Many observers had predicted that weather or technical delays, which are relatively common, would force just such a revision of the tightly packed launch calendar.

NASA has been flying missions at a rapid clip as the space agency seeks to complete its share of construction of the International Space Station and retire the shuttles. The past six shuttle flights have been to the space station, and both remaining missions are station runs as well.

Curie says that the space shuttle program is reviewing the issue and that a final decision will be made July 1. "The shuttle program is funded through the first quarter of [fiscal year] 2011 to fly missions, and there is no issue with moving STS-134 into February," he adds.

Photo of a space shuttle on the launch pad at Kennedy Space Center in Florida: NASA/KSC