NASA Schedules Shuttle for Liftoff

KENNEDY SPACE CENTER, Fla. — NASA officials Friday scheduled space shuttle Endeavour to lift off Thursday morning after deciding that repairs conducted on the launch pad fixed potential O-ring problems.

Over the past week, technicians, wearing special suits to prevent static electricity that could ignite the rockets, were placed in the bell-shaped nozzles of Endeavour’s two solid rocket boosters.

The workers replaced putty that insulates nozzle joints, using a small pump as a vacuum to prevent air pockets.

During the past two shuttle launches, NASA has discovered, air pockets allowed hot rocket gas to penetrate the putty and singe the O-rings in a particular nozzle joint. The problem caused almost a month’s delay in Endeavour’s science mission originally scheduled for early August.

Shuttle manager Tommy Holloway said he is satisfied with the repairs though there are no tests to verify the launch-pad work. Identical repairs were performed successfully on spare nozzles by booster manufacturer Thiokol Corp. in Utah, using the same workers, the same kind of putty and the same procedures.

A leak in a different booster joint caused Challenger to explode shortly after liftoff in 1986, killing all seven crew members aboard.

Shuttle officials insist the singed O-rings in the booster nozzles of Atlantis and Discovery in June and July caused no added danger.