Discovery grounded

2005-07-13 22:23

Cape Canaveral - A fuel gauge that mistakenly read empty instead of full forced the National Aeronautics and Space Administration to call off Wednesday's launch of Discovery on the first shuttle flight since the February 2003 Columbia disaster.

The space agency's chief said the mission was off until at least Monday.

The decision to scrub the launch came with less than two-and-a-half hours to go, while the seven astronauts were boarding the spacecraft for their journey to the international space station.

Up until then, rain and thunder over the launch site appeared to be the only potential obstacle to an on-time lift-off.

The problem involved one of the external fuel tank's four engine cut-off sensors, which are responsible for making sure the spacecraft's main engines shut down at the right moment during the ascent.

A launch could end in tragedy if faulty sensors caused the engines to cut out too early or too late.

A similar, baffling problem cropped up during a launch-pad test in April, and Nasa has been struggling ever since to figure out the source of the trouble.

'Not a setback'

Nasa administrator Michael Griffin said it was unclear whether the shuttle could be fixed at the launch pad or would have to be rolled back to the hangar, which would mean a much-longer delay.

"It's not a setback at all. We're fine if we go anytime in the launch window," Griffin said.

"We had one mission for the defence department that scrubbed 14 times. This is nothing!"

The space agency has until the end of July to launch Discovery, after which it will have to wait until September - a window dictated by both the position of the space station and Nasa's desire to hold a daylight lift-off in order to photograph the shuttle during its climb to orbit.

Nasa said it appeared the sensor was showing a low fuel level, even though the tank was full with two million litres of super-cold liquid hydrogen and oxygen.

'Many things can go wrong'

Sherwood Boehlert, chair of the house of representatives' science committee, said after being briefed by Nasa officials on Wednesday: "I'm confident they will solve the problem and there will be successful launch, probably next week."

"There are thousands and thousands of parts and many things can go wrong.

"Let me emphasise, the success was in identifying the problem," said the congressman in the space agency's defence.

"I think Nasa's taking every problem that develops very seriously."

Nasa officials speculated that the problem could be either with the sensor itself, the cables, or the electronics aboard Discovery.

- AP