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Nasa Calls off Shuttle Launch of Faulty Sensor

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NASA Calls Off Shuttle Launch Over Faulty Fuel Sensor

By MIKE SCHNEIDER, AP

 

 

 

AP

NASA delayed the launch of the space shuttle Discovery, the first flight in more than 2 years.

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CAPE CANAVERAL, Fla. (July 13) - A faulty fuel gauge on Discovery's external tank forced NASA to call off Wednesday's launch of the first shuttle flight since the Columbia disaster 2 1/2 years ago. The space agency did not immediately set a new launch date.

 

The decision came with less than 2 1/2 hours to go before launch, as the seven astronauts were almost done boarding the spacecraft. Up until then, rain and thunder over the launch site appeared to be the only obstacle to an on-time liftoff.

 

The same baffling problem cropped up during a launch pad test back in April, and NASA has been struggling ever since to figure out the source of the trouble. But the topic came up repeatedly at meetings of top-level NASA managers this week, and the space agency said that it believed it had worked around the problem by replacing cables and other electronics aboard the shuttle.

 

As recently as Monday, NASA deputy shuttle program manager Wayne Hale described the sensor problem seen in April as simply an ''unexplained anomaly.''

 

The back-to-back failures suggest the possibility of a wider problem than one or two bad pieces of equipment.

 

A launch control commentator said that it was unlikely the problem could be solved quickly and that another launch attempt on Thursday was all but impossible. NASA officials refused to speculate on whether the shuttle would have to be rolled back to the hangar for repairs.

 

NASA has until the end of July to launch Discovery, after which it will have to wait until September - a schedule dictated by both the position of the international space station and NASA's desire to hold a daylight liftoff in order to photograph the shuttle during its climb to orbit.

 

The problem was with one of the four engine cut-off sensors, which are responsible for making sure the spacecraft's main engines shut down at the proper point during the ascent. A launch could end in tragedy if faulty sensors caused the engines to cut out too early or too late.

 

 

NASA said it appeared that the sensor was showing a low fuel level, even though the tank was full with 535,000 gallons of super-cold liquid hydrogen and oxygen.

 

The sensors ''for some reason did not behave today and so we're going to have to scrub this launch attempt,'' launch director Mike Leinbach told his team. ''So appreciate all we've been through together, but this one is not going to result in a launch attempt today.''

 

During a fueling test of Discovery's original tank in April, one of its sensors gave intermittent readings. NASA could not figure out the exact reason for the failure but replaced the entire tank anyway to install a heater to prevent a dangerous ice buildup.

 

Shuttle managers considered conducting a fueling test at the launch pad on the replacement tank, but ruled it out to save time, saying that the actual fueling on launch day would be the ultimate test.

 

''We are disappointed, but we'll fly again on another day,'' said an astronaut speaking from launch control, David Wolf.

 

 

AP-NY-07-13-05 14:42 EDT

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