The U.S. space agency NASA remains puzzled about a technical problem that is preventing the first launch of a space shuttle since late 2002. Mission officials have not set a new launch date for the orbiter Discovery while they continue troubleshooting a faulty fuel level sensor.
On Thursday, shuttle officials had said that they would first look for the simplest solution to the sensor difficulty, which meant checking things like wire connections. On Friday, however, deputy shuttle manager Wayne Hale said the problem seems more complex than loose wires.
"The simple things, the things we did quickly, did not provide us any resolution to the problem. It's possible that we could be back into countdown and looking at a launch in the latter half of the week, but that would require a near term lucky find. As we get into the more detailed testing, we obviously are moving into fixes that might take longer," he said.
Mr. Hale says NASA still hopes to launch Discovery to the International Space Station this month and would consider extending the launch opportunity a few days into August if the length of the day permits. This particular time period allows a daytime launch while the station is in the optimum position to be reached in orbit. The next daytime opportunity will not come until September, and then November after that.
The agency needs sunlight during takeoff for this mission so high resolution cameras can document whether its many safety modifications have prevented debris from falling off the external fuel tank and endangering the shuttle. Hard foam from the tank punctured the orbiter Columbia during liftoff more than two years ago and doomed it to disintegrate in flight.
The fear concerning the troublesome fuel level sensor is that it might cause the shuttle engines to cut off prematurely upon the climb to orbit. Mr. Hale says the problem was first identified in April, but corrected itself before technicians could find an explanation. With its return, the NASA official says the agency has stepped up its hunt for the cause.
"I would say that I'm very hopeful because we're taking this troubleshooting to a significantly higher level than we took it the first time, and I feel very confident that we will get a solution to our problems," he said.
The space station crew is awaiting the shuttle because it is carrying important replacement equipment and supplies. When Discovery does reach the outpost, its astronauts will take a spacewalk to test new ways of repairing shuttle damage caused by launch debris.