NASA Watches Weather for Tuesday Shuttle Launch

This story was updated at 2:00 p.m. EDT.

CAPE CANAVERAL, Fla. - NASA is watching the weather for Tuesday?s planned launch of the space shuttle Discovery.

Rain showers and thick clouds are the chief hurdles facing Discovery?s upcoming space shot, with current forecasts predicting a 60 percent chance of favorable launch conditions. The clock began counting down to the shuttle?s planned launch at 2:00 p.m. EDT (1800 GMT) today.

?We have several concerns for launch day,? said NASA shuttle weather officer Kathy Winters in a mission update here at the Kennedy Space Center (KSC).

Winters said a frontal boundary of weather will bring rain showers over Discovery?s launch site today and throughout early next week, but should steer clear by Tuesday. Only remaining rain showers and thick clouds may post a threat to Discovery?s launch, she added.

Commanded by veteran shuttle astronaut Pamela Melroy, Discovery?s seven-astronaut crew is set to launch on Oct. 23 at 11:38 a.m. EDT (1538 GMT) to begin a 14-day construction flight to the International Space Station (ISS). Discovery will deliver the vital connecting node Harmony and ferry a new crewmember to the station as part of NASA?s STS-120 mission.

?We are tracking no issues in our preparations at this point," NASA test director Charlie Blackwell-Thompson told reporters.

Shuttle workers are expected to begin loading the super-cold liquid hydrogen and liquid oxygen used to power Discovery?s three fuel cells at 10:00 a.m. EDT (1400 GMT) on Sunday, but could delay the operation should poor weather intervene, said Blackwell-Thompson, adding that there is plenty of time to make up any delayed work in time for Tuesday?s launch.

NASA has until Dec. 11 to launch Discovery?s STS-120 mission, but plans to make up to four attempts within five days, beginning with the Oct. 23 opportunity. Should weather prevent Tuesday?s planned launch, the weather outlook remains the same - 60 percent chance of favorable launch conditions - for Wednesday and Thursday, Winters said.

Meanwhile, the 31,400-pound Harmony connecting node and a trio of spare space station parts are stowed inside Discovery payload bay and ready for their trip to the ISS. With its multiple attachment points, Harmony will serve as a hub for future international laboratories to be launched to the space station. The first new laboratory - the European Space Agency?s Columbus module - is slated to launch aboard the shuttle Atlantis on Dec. 6.

?We are ready to go," said NASA?s STS-120 payload manager Glen Chin.

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