Shuttle launch delayed one day because of cold

CAPE CANAVERAL, Fla. -- NASA postponed Thursday's liftoff of space shuttle Columbia for a day because of the potential for the coldest launch-time temperature since the Challenger disaster in 1986.

Liftoff had been set for sunrise, with temperatures forecast in the 30s. Warmer weather was expected for Friday's attempt to send Columbia on a mission to overhaul the Hubble Space Telescope.

As forecasters watched the thermometer Wednesday, engineers scrambled to resolve last-minute concerns over improperly manufactured wheel bearings.

Wheel bearings studied

Eight bearings in Columbia's main landing gear evidently were tempered with 300-degree heat rather than the intended 500 degrees.

Three engineering teams spent the day trying to determine whether the steel roller bearings were strong enough to support a 200 mph shuttle landing. A failed bearing could cause a wheel to lock up and the shuttle to skid down the runway with potentially disastrous consequences.

"Do I feel confident? If I was going to bet, I would bet that we can put it to rest" and proceed with liftoff, said Stephen Oswald, Boeing's shuttle program director and a former shuttle commander. The delay gave engineers more time to review the data.

Like NASA's last shuttle countdown in December, this one was being conducted amid high security in case of a terrorist attack. The Air Force had F-15 jets on patrol, and the Federal Aviation Administration ordered a no-fly zone within 35 miles of the launch pad beginning Thursday night. Meteorologists had expected a temperature of just 38 degrees at sunrise Thursday. The temperature should be around 49 degrees at launch time Friday morning.

The coldest day NASA ever launched a space shuttle was a 36-degree January morning in 1986. O-ring seals in Challenger's right solid-fuel rocket booster deteriorated during the overnight freeze, and hot gases leaked from the joint at liftoff. The shuttle exploded 73 seconds into its flight, killing all seven astronauts aboard.

New parts for Hubble

Columbia is carrying $172 million worth of new Hubble parts for the most complex servicing mission to the telescope yet. It surpasses even the first one in 1993 to correct the telescope's blurred vision.

During the 11-day flight, spacewalking astronauts will install an advanced camera for peering farther and more clearly into the universe, a refrigeration system for resuscitating an infrared camera that has been disabled for three years, a pair of stronger and more efficient solar wings, a power-control unit and a steering mechanism.

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