Briefing Now Set for 4:30 p.m.

The launch postponement news conference now will be at 4:30 p.m. EDT. The participants still will be shuttle Launch Integration Manager Mike Moses and STS-128 Launch Director Pete Nickolenko. Managers also decided to reset the launch countdown and hold at the T-11 point. If approved by shuttle management, the count will resume 8:34 a.m. Friday.

Launch is targeted for 11:59 p.m. Friday. The weather forecast calls for a 60 percent chance of acceptable conditions at launch time. The main concerns are for anvil clouds and thunderstorms within 20 miles of the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida, launch site for the shuttles.

Teams will begin closing the Rotating Service Structure around space shuttle Discovery at approximately 4:15 p.m. EDT in order to replace Tyvek covers on the shuttle's thrusters. The work is expected to take six to seven hours. When completed, the team again will move the RSS to the park position in preparation for Discovery's targeted launch attempt Friday at 11:59 p.m.