Weather Forecast Is Good For Twilight Liftoff At 7:43 pm EDT

NASA says repairs are under way on the Ground Umbilical Carrier Plate (GUCP) interface, where gaseous hydrogen leaked during Wednesday's launch attempt of the space shuttle Discovery.

Once repairs are completed, the interface will be retested and leak checked before Sunday's planned launch attempt at 7:43 pm.

The Mission Management Team will meet on Saturday at 1 pm to review the data and the progress of the teams, and make a final determination on the launch. A Prelaunch News Conference will be held following the MMT to announce whether the countdown will proceed towards T-minus zero Sunday evening.

The weather forecast calls for an 80 percent chance of acceptable conditions at launch time, though Shuttle Weather Officer Kathy Winters says meteorologists are watching for low cloud ceilings.

As far as weather conditions go, Sunday represents the last best chance for NASA to launch Discovery before the forecast deteriorates at the start of the week.
The STS-119 mission would last 13 days if Discovery launches Sunday; if launched later, that timeline could be compromised.

As ANN reported, NASA discovered a potentially catastrophic hydrogen leak while fueling the orbiter Wednesday morning. The leak developed on the piping that runs from the fixed service structure to a valve at the intertank section of the shuttle's external tank. The pipe moves hydrogen gas away from the shuttle and to a flare stack near the launch pad that burns it away safely.

Originally scheduled to liftoff February 12, Discovery was grounded for a month as NASA examined hydrogen flow control valves linking the external tank to the orbiter. One of those valves was found cracked after Endeavour returned from its mission in November; NASA opted to swap the valves originally installed on Discovery, with lower-time parts.

FMI: www.nasa.gov/shuttle