Heat Wave Improves Shuttle Endeavour's Wednesday Launch Outlook

CAPE CANAVERAL, Fla. ? Thanks to a heat wave, NASA shuttle officials improved tomorrow's launch weather forecast for the space shuttle Endeavour by 10 percent.

The heat wave, which forecasters are calling the "ring of fire," is pushing out typical thunderstorm conditions here at the Kennedy Space Center (KSC), prompting NASA's shuttle weather officer Kathy Winters to raise Endeavour's chance of an on-time launch from 70 percent to 80 percent. Endeavour and its seven-astronaut crew are set to launch Wednesday at 6:36 p.m. (2236 GMT) on a construction flight to the International Space Station.

"The drier air that we've had in the area is causing us to have less thunderstorm activity, less showers," Winters said in a Tuesday mission status briefing. "The same thing that's causing the hot temperatures is the same thing that's allowing us to have good weather for launch."

Meanwhile, shuttle technicians finished the delicate procedure of loading the propellant to feed Endeavour's fuel cells early this morning, which will provide on-board power for the spacecraft.

Jeff Spaulding, NASA's shuttle test director, said the shroud-like Rotating Service Structure that shields Endeavour from weather at its Pad 39A launch pad is set to retract at 9:00 p.m. EDT (0100 Aug. 8 GMT) this evening. The six-hour process of loading the shuttle's 15-story fuel tank with its super-cold liquid oxygen and liquid hydrogen propellant is scheduled to start at 8:11 a.m. EDT (1211 GMT) tomorrow morning.

As the weather system pushes away the chance of thunderstorms on launch day, astronauts continue preparing for their expected liftoff.

Commanded by veteran astronaut Scott Kelly, Endeavour's ?STS-118 crew are gearing up for an 11-to-14 day mission install a new starboard-side spacer segment on the space station's backbone-like main truss. The astronauts also plan to deliver fresh cargo, spare parts and experiments to the orbiting laboratory.

Teacher-turned-astronaut Barbara Morgan, an STS-118 mission specialist, is set make her first journey into space Wednesday as a member of Endeavour's crew. Her flight has been 22 years in the waiting, as Morgan was Christa McAuliffe's backup during NASA's Teacher in Space program, which ended shortly after the 1986 Challenger tragedy.

• VIDEO: Teaching the Future: Teacher-Astronaut Barbara Morgan
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• IMAGES: Barbara Morgan, Crewmates Train for STS-118