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NASA cancels Thursday launch plans

By IRENE BROWN, UPI Science News

CAPE CANAVERAL, Fla., Feb. 27 (UPI) -- NASA on Wednesday decided to delay launch of shuttle Columbia on a Hubble Space Telescope servicing mission because of expected cold temperatures and ongoing analysis of suspect bearings in the spaceship's landing gear.

Launch of the first mission of the year had been planned for 6:48 a.m. ET on Thursday. However, temperatures are forecast to be as low as 38 degrees Fahrenheit -- NASA's post-Challenger cold weather limit. In addition, engineers need more time to assess if shuttle Columbia is safe to fly despite the discovery of eight questionable bearings in the spaceship's landing gear.

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Blastoff was rescheduled for 6:22 a.m. Friday. The weather is expected to be warmer, with meteorologists forecasting an 80 percent chance of acceptable conditions for launch, said shuttle weather officer Ed Priselac.

The shuttle is scheduled to rendezvous with the Hubble Space Telescope so teams of space-walking astronauts can make repairs and upgrade the observatory's imaging systems.

Questions about Columbia's landing gear surfaced during a top-level mission managers meeting on Tuesday. At a briefing Wednesday morning, NASA spokesman George Diller said three teams of engineers had been formed to study the problem and mangers were hopeful any questions would be resolved by Wednesday night, when the shuttle's external fuel tank is to be filled for launch.

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"They're starting to get comfortable, but there's still a lot more data analysis to do," said Diller.

Initially, engineers believed the questionable bearings had not been heat-treated at the proper temperature. Additional investigation showed the bearings in question also were slightly different than the required design.

The issue arose out of a routine landing gear test last month at Wright-Patterson Air Force Base. During a simulated landing, the bearings were fine, but one cracked during a second landing. Engineers then realized the cracked bearing was not what was designed to be in the landing gear. NASA is not sure how eight of the non-specified bearings made it into shuttle Columbia's landing gear.

Engineers want additional time to determine if the shuttle is safe to fly as is. If the bearings need to be replaced, the mission to service the Hubble telescope would face a delay of several weeks.

Failure of the shuttle's landing gear could be disastrous, said shuttle program manager Ron Dittemore.

"If you lose the bearing ... your wheel isn't going to turn very well and it could lock up," Dittemore said. "Then you've got a real problem going down the runway ... at 200 miles per hour. The wheel doesn't roll, it starts to skid. That would be a real bad day."

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