NASA plans next launch attempt after a glitch grounds Endeavour

NASA plans next launch attempt after a glitch grounds Endeavour

By Tony Lee Orr

GCN Staff

After a computer glitch and foul weather prevented last week's launch of the space shuttle Endeavour, NASA set a new liftoff date for no earlier than Wednesday.

The problem in the shuttle's backup master events controller occurred Jan. 31 during the initial launch attempt, said Kelly Humphries, a NASA spokesman at Johnson Space Center in Houston.

The controller is one of a pair that govern commands for solid rocket booster ignition and booster and external tank separation during powered flight.

Operating with only one controller would put the six-astronaut crew at risk of a Critical 1 failure'complete loss of the aircraft and its crew'if the controller were to malfunction.

During the launch attempt, the second controller in the aft engine compartment failed a standard test procedure about a half hour before takeoff, Humphries said. During the test, computers send the 65-pound, microwave-oven-size avionics boxes a series of commands that prompt a response. In this case, the response wasn't the one expected.

The controller later passed the test, Humphries said.

'It wasn't proven to be bad or good,' he said. 'It was working at the last minute. [Launch officials] had decided that they could go ahead and launch.'

But sheets of rain and dense clouds led them to change their minds.

'When the weather kept them from going, the team of engineers met throughout the evening and overnight to better understand the failure and why [the second controller] passed an additional test,' Humphries said. The launch team members decided to replace both controllers because 'they didn't understand what happened.'

NASA will analyze the controllers to figure out the problem, he said.

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