Fuel glitch may not stop space shuttle launch

CAPE CANAVERAL - NASA is prepared to launch its first space shuttle mission since the Columbia accident 2-1/2 years ago even if a technical glitch that grounded Discovery on July 13 reoccurs, the US space agency says.

The launch of Discovery is scheduled for 10:39 am EDT (local time) on Tuesday, and is under intense scrutiny because of safety upgrades and other changes implemented after Columbia fell apart over Texas in February 2003, killing seven astronauts.

"I think what you want coming out of the Columbia accident, the loss of Columbia and the soul-searching examination that NASA has undertaken since then, what you want of NASA is that we make the right technical decisions, that we do the right thing to the extent that we can figure that out, which is hard," said NASA administrator Michael Griffin.

"We can't restrict the range of our options to those things which are going to present well necessarily," he said.

NASA flight rules require all four of the shuttle's hydrogen fuel sensors to be working before liftoff.

The instruments would shut down the shuttle's main engines before they run out of hydrogen fuel to avoid a potentially catastrophic explosion. The engine shutdown would occur if two of the four sensors register an empty tank.

When one sensor failed a routine prelaunch test during Discovery's first launch attempt on July 13, managers canceled the flight. Exhaustive tests, however, failed to reveal the cause of the glitch.

Technicians did find and fix three subtle electrical grounding issues with equipment that feeds the sensor data to an electronics box in the shuttle's aft engine compartment.

"It is possible that we have caused the problem to go away," shuttle deputy program manager Wayne Hale said.

Managers also swapped the suspect sensor's connector with another sensor so that if the problem reoccurs, engineers will have more information about whether the sensor itself, the wiring or the electronics box is at fault.

If the tests assure managers that the problem is isolated to a single sensor, NASA plans to waive its flight rule and launch the shuttle, provided all other systems and the weather is acceptable for launch.

'GHOSTS OF COLUMBIA'

"If it reoccurs we think we have a really good understanding and really good plan to go forward with," Hale said.

"I wake up every day and I ask myself 'Are we pushing too hard? Are we doing this thoroughly? Have we done the right technical things? Have we asked the right people? Have we built the tests properly?'

"I think we are all still struggling a bit with the ghosts of Columbia and therefore we want to make sure we do it right," Hale added.

Shuttle Columbia was destroyed during a landing attempt on Feb. 1, 2003. A piece of foam that fell off the shuttle's fuel tank during launch had damaged the ship's wing, and as it flew through the atmosphere for landing, superheated gases blasted into the hole.

NASA had long overlooked what effect debris could have on the shuttle. Managers said they are not making the same mistake by preparing to change a flight rule to launch Discovery.

"Our team is making a clear point that they are not brushing away unexplained factors and saying they don't matter," Griffin said.

"They are reducing the issue to a situation where there are two or three unexplained and, at this point, unexplainable possibilities that we simply won't find until we tank up and test," he said.

- REUTERS