Shuttle Launch Is Delayed Until Late Next Week

The launch of the space shuttle Discovery was pushed back into late next week after NASA managers decided Friday they could no longer hold engineers and launch workers in a continual countdown status.

“We are on a day-by-day basis,” said N. Wayne Hale Jr., deputy shuttle program manager.

He insisted, however, that “we are not in any sense of the word becoming pessimistic about meeting the July (launch) window.”

“We have the entire resources of the agency behind us,” Hale added.

NASA shuttle managers said they had more than 100 items on the so-called “fault tree” left to look at to determine what caused a fuel sensor to fail 2 1/2 hours before Discovery’s scheduled launch Wednesday.

A dozen engineering teams were working on the problem, which first arose during a test in April when two sensors failed. The sensors are designed to shut off the liquid hydrogen fuel before the engines run dry.

After that failure, NASA managers replaced an external fuel tank and thought they had solved the problem.

Instead, another sensor, one of four monitoring hydrogen fuel levels, failed during countdown Wednesday.

Though space agency officials said they remained uncertain about the cause, they were concentrating on what was known as the point sensor box, a complex piece of electronics located in the aft portion of the orbiter.

The box receives signals from the sensors located at the bottom of the liquid hydrogen portion of the fuel tank, which is chilled to minus 420 degrees Fahrenheit during launch.

“A team is looking at the history of the box dating to the time of manufacture in the early 1980s,” said John F. Muratore, NASA’s manager for shuttle systems engineering.

He said engineers did not think the problem was related to changes made to the fuel tank after the Columbia shuttle accident in 2003.

“We are working here very hard,” Hale said. “We are hopeful we will find something in the next two or three days and get off the pad and launch.”

It will take a minimum of four days after the problem is fixed to get the shuttle ready for launch. Hale said the earliest possible launch day now was late next week.

If work requires rolling the shuttle back to the Vehicle Assembly Building, it would take at least 10 days to get the shuttle back to the launch pad.

Following Wednesday’s scrub, space center employees were placed in a 48-hour countdown hold in hopes that the problem could be quickly solved. When it became apparent it could not be, the management team decided to call off the hold.

“We had several hundred people here at [Kennedy Space Center] and several hundred more at Johnson Space Center [in Houston] who were at the controls,” NASA spokesman Bruce Buckingham said. “We need to give them some time off.”

Discovery’s seven-member crew was secluded at Kennedy Space Center. Buckingham said they had the option to return to their homes in Houston during the delay.

If Discovery cannot be launched by the end of July, the next launch window that would allow the shuttle to reach its destination, the International Space Station, is in September.