NASA to launch shuttle even if a fuel gauge fails

CAPE CANAVERAL, Fla. -- NASA said yesterday it will launch the space shuttle Discovery even if the fuel gauge problem that halted the countdown two weeks ago resurfaces. It would be the first space shuttle flight in 2 1/2 years.

Discovery is set to lift off tomorrow at 10:39 a.m., the same time Columbia took off on its doomed mission in 2003.

Deputy shuttle program manager Wayne Hale said the fuel gauge problem has been a vexing one -- engineers still do not know exactly what caused it -- and he has asked himself, ''Are we taking care enough to do it right?"

''Based on the last 10 days' worth of effort, the huge number of people and the tremendous number of hours that have been spent in testing and analysis, I think that we're coming to the right place," he said.

At an evening news conference, Hale and other NASA officials defended the decision to launch with a fuel gauge failure. They stressed that they will proceed with a liftoff only if the problem is well understood and involves the gauges in question -- anything else would result in a postponement.

NASA's launch rule, which has been in place since the 1986 Challenger disaster, requires that all four hydrogen fuel gauges in the external tank be working properly. Going with three out of four would result in a ''deviation" in the rule, Hale said.

''I am committed -- and I think the whole team is committed -- to doing this in a safe manner," Hale said. ''I think we're all still struggling a little bit with the ghost of Columbia and therefore we want to make sure we do it right."

NASA administrator Michael Griffin said he supports the decision and even hopes the problem recurs to further pinpoint the source of the trouble.

Workers last week repaired faulty electrical grounding inside Discovery in hopes that would solve the fuel gauge problem that cropped up during the launch attempt on July 13. They also swapped the wiring between the troublesome fuel sensor and another one to better understand the issue if it reappears. The same type of problem occurred in April and was written off then as an ''unexplained anomaly."

The fuel gauges are needed to prevent the main engines from shutting down too soon or too late during liftoff, in the event of an extreme problem like a leaking tank. The first scenario could result in a risky emergency landing; the second could cause the engine turbines to rupture and could destroy the spacecraft. Only two fuel gauges are needed to avoid such situations, but NASA requires all four to be working at liftoff for redundancy.