Atlantis To Head To Orbit At 12:29 EDT

The weather looks good... the shuttle looks good... and if it all comes together in a way it hasn't during three previous attempts, Atlantis should be headed for space Wednesday afternoon.

Launch time from the Kennedy Space Center is set at 12:29 EDT, on a long-delayed mission to continue the construction of the International Space Station. Weather officials are predicting favorable conditions for Wednesday's launch attempt, with a 30-percent chance of weather prohibiting the launch.

A low-pressure area may develop over Central Florida on Wednesday, increasing the potential for moisture in the atmosphere. However, the early launch time is expected to avoid the afternoon thunderstorms.

The primary concerns for launch are cumulus clouds within 10 nautical miles of the launch pad and isolated showers within 20 nautical miles of the Shuttle Landing Facility.

STS-115 carries a 17.5 ton addition to the station's power generation apparatus. Its six crew members will conduct a number of spacewalks to install the equipment and otherwise help out around the house while they're at the station.

If, for some reason, Atlantis can't launch as scheduled Wednesday... there are two more launch opportunities on Thursday and Friday. 

That's a little out of the ordinary for crews at KSC. Usually, if a mission is scrubbed twice in a row, the launch team stands down for a few days to gather its collective breath and make sure everything is ready for the next try.

Because of a pending Soyuz launch aimed at rotating the ISS crew, however, the window is extremely tight.

If Atlantis can't get off the ground by Friday... there's not much chance at all that it will launch before next month.

FMI: www.nasa.gov/shuttle