Shuttle Liftoff Reset Despite Glitch

With time running short on the current launch window, NASA decided Thursday to attempt a liftoff of the space shuttle Atlantis today despite a problem with one of the craft’s fuel cells.

Shuttle program officials said a possible electrical short in a pump motor connected to the fuel cell did not pose a safety hazard to the spacecraft and its six-person crew.

After studying the electrical problem for two days, managers gave the go-ahead for launch after satisfying themselves that the problem was isolated to one fuel cell.

“It is certainly acceptable to go forward, and the risk is minimal,” said Steve Poulos, manager of the orbiter projects office.

The decision to move forward with a launch was made over the objections of the manufacturer of the 30-year-old fuel cell and its motors, United Technologies Corp. of Hartford, Conn.

Company officials recommended swapping out the problem fuel cell with a new one.

NASA safety officials made the same recommendation during a lengthy mission management team meeting Thursday afternoon.

But shuttle program manager N. Wayne Hale Jr. said neither the manufacturer nor the safety director was worried about crew safety.

The worst that might happen, Hale said, was that the problem fuel cell could malfunction. Even if that happened, the craft could operate perfectly well with the two remaining cells, he said.

Although NASA engineers were unable to analyze the fuel cell, located under the filled payload bay, their best guess was that a small wire in the pump shorted out due to fatigue. The fuel cell can operate even with the shorted wire.

Hale characterized the problem as a random event.

But the last time this fuel cell flew, in 1999, the shuttle suffered a short during liftoff.

The mission was unaffected, and officials said the current electrical problem was unrelated.

“Here we are, 30 years after they put together this one little motor. Finally, we had a little incident,” Hale said. “I wish my car was that good.”

Atlantis’ mission will restart assembly of the International Space Station.

In its payload bay, the shuttle is carrying 17.5 tons of equipment, including a station truss and solar power arrays that will double the amount of energy produced by the station.

This will be the first assembly flight in four years. Assembly was halted after the loss of the shuttle Columbia in 2003.

Weather is expected to be good for today’s attempt. Officials said there was a 30% chance of thunderstorms, which would prohibit a launch.

Officials said there was a 20% chance of bad weather Saturday, the last possible day before NASA would have to stand down until at least the end of September.

john.johnson@latimes.com