Ice build up was believed to have caused a baseball-sized piece of foam to pop off a bracket, bounce off a strut and gouge a divot in the thermal tiles on Endeavour's underbelly during the last mission in August.
The delay plus alterations to the foam and brackets are expected to reduce the possiblity of simiar foam loss, said Payne.
"Weather conditons are such that we're not expecting icing issues," Payne said.
Bad weather in the form of rain and low cloud ceiling could be a problem, said Shuttle Weather Office Kathy Winters.
Only a 40 percent chance of weather allowing the launch is predicted, she added. Overseas emergency landing sites have acceptable weather. If a 24-hour delay is necessary, weather improves to a 60 percent chance of favorable launch conditions.
No launch issues besides the weather have arisen, said Payne.
Fueling the shuttle will begin at 2:13 a.m. Tuesday, while the crew will head for the launch pad about 8 a.m., said Payne.
The STS-120 mission will be the 23rd shuttle flight to the International Space Station, delivering the Italian-built U.S. Node 2, called Harmony. The seven-member crew includes ESA astronaut Paolo Nespoli from Italy. The 14-day mission includes five spacewalks -- four by shuttle crew members and one by the station's Expedition 16 crew -- to install Harmony and move the P6 solar arrays to their permanent position and deploy them.
Shuttle managers have said that, despite the fact that the safety reviews are completed for the flight, NASA has not stopped its effort to review the concerns about silica carbide coating damage on the heat-shielding wing panels on the front edge of Discovery's wings. A safety team recommended replacing them pre-flight, which would have delayed launch by about 60 days.
Instead, agency managers have decided that the coating cracks do not pose unwarranted danger to the spaceship or crew so they are going ahead with the mission.
"That is a continuous ongoing effort," launch integration manager Leroy Cain said Sunday. New information could always become available and it would be immediately reviewed. The problem affects panels on all three orbiters, not just Discovery.
A reporter reminded Cain that he was the entry flight director for the ill-fated Columbia mission and asked whether, knowing all that he knows and experiencing all that he has experienced, is he personally comfortable with the decision made.
"Yes, I am," Cain said Sunday.
Additional STS-120 resources:
WARNING AREA FOR MARINERS:
The attached map shows the Eastern Range's Launch Hazard Area (LHA) for the scheduled launch of space shuttle mission STS-120 on Tuesday, Oct. 23, 2007. The targeted launch time is 11:33 a.m. (EDT).
For their safety, mariners are asked to remain clear of the LHA from 9 a.m. through 1 p.m. The exact coordinates of the LHA are shown on the attached map.
Click here for map.
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