NASA tests newly installed engine

NASA contractor technicians are testing a newly installed engine on shuttle Discovery, the orbiter being readied for launch on the agency's second post-Columbia test flight.

Taking place inside Orbiter Processing Facility Bay 3 here at Kennedy Space Center, the tests are aimed at making sure the engine is not leaking.

The engine it replaced was removed from Discovery earlier this week as a result of concerns that cropped up recently at Stennis space Center in Mississippi.

Engineers examining an engine there discovered a cracked solder joint on one of two power supplies associated with its computer controller.

The failure of both in flight would cut power to the controller. The controller operates in conjunction with engine sensors, valves, actuators and spark igniters to provide for engine control, checkout and monitoring.

Engineers think the crack might have been caused by the high number of thermal cycles the engine had been put through over the course of time.

Managers decided to change out the No. 2 engine on Discovery as a precaution because it had a similar thermal cycle history.

Discovery remains scheduled to move from its processing hangar to the Kennedy Space Center Vehicle Assembly Building on May 12. Launch remains scheduled for July 1.