Cape Canaveral, Fla. – A faulty fuel-gauge reading forced NASA to call off today’s launch of Discovery on the first shuttle flight since the Columbia disaster 2 1/2 years ago. The mission was put off until at least Saturday.
The decision to scrub the launch came with less than 2 1/2 hours to go, while the seven astronauts were boarding the spacecraft for their journey to the international space station. Up until then, a thunderstorm over the launch site looked like the only potential obstacle.
The problem involved one of the external fuel tank’s four hydrogen fuel sensors, which are responsible for making sure the spacecraft’s main engines shut down during the ascent when the tank runs out of fuel. A launch could end in tragedy if the engines cut out too early or too late.
Similar sensor trouble cropped up intermittently during a launch pad test back in April, and NASA was never able to get to the bottom of the problem, but it pressed ahead with a launch anyway.
“It’s not a setback at all. We’re fine if we go anytime in the launch window,” NASA Administrator Michael Griffin said. “We had one mission for the Defense 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 liftoff in order to photograph the shuttle during its climb to orbit.
NASA officials said it was not clear whether the problem was with the sensor itself or with the cables or the electronics boxes aboard Discovery. It was also 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.
Deputy shuttle program manager Wayne Hale said that even in a best-case scenario, the shuttle will not be ready for launch before Saturday.
Rep. Sherwood Boehlert, R-N.Y., chairman of the House Science Committee, said after being briefed by NASA officials today: “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 stress, the success was in identifying the problem,” the congressman said in the space agency’s defense. “I think NASA’s taking every problem that develops very seriously.” The sensor problem cropped up during launch preparations today. When NASA tested the system by simulating a dry fuel tank, the sensor mistakenly showed a full tank, officials said.
The sensors “for some reason did not behave today,” launch director Mike Leinbach told his team. “So appreciate all we’ve been through together, but this one is not going to result in a launch attempt today.” During a fueling test of Discovery’s original tank in April, one of its sensors worked on and off. NASA could not figure out the exact reason for the failure but replaced the entire tank anyway to install a heater to prevent a dangerous ice buildup. Cables, connectors and other electronics aboard the shuttle were also replaced.
The sensor problem came up repeatedly at meetings of top-level NASA managers earlier this week, but the space agency said that it believed it had resolved the problem. As recently as Monday, Hale described the sensor trouble as simply an “unexplained anomaly.” Shuttle managers considered conducting a fueling test at the launch pad on the replacement tank, but ruled it out to save time, saying that the actual fueling on launch day would be the ultimate test.
A scrubbed launch costs NASA $616,000 in fuel and labor.
