Fuel gauge problems stall shuttle mission

Launch delayed a 2d time after failure of devices

Space shuttle Atlantis sat on the launch pad at Kennedy Space Center yesterday after NASA postponed its launch until January because of technical problems with the fuel tank gauges. (NICHOLAS KAMM/AFP/Getty Images)

CAPE CANAVERAL, Fla. - NASA yesterday delayed the launch of space shuttle Atlantis until January after a gauge in the fuel tank failed for the second time in four days.

With only a few days remaining in the launch window for the shuttle's mission to the international space station, senior managers decided to stand down in hopes of better understanding the perplexing and persistent fuel gauge problem.

"We're determined to get to the bottom of this," said LeRoy Cain, chairman of the mission management team.

Whether Atlantis can fly as early as Jan. 2 "is all going to depend on what we find out," he said.

The trouble with the fuel gauge resurfaced just before sunrise yesterday, about an hour after the launch team began filling Atlantis's big external tank for the afternoon liftoff.

Shuttle managers had said they would halt the countdown and call everything off if any of the four hydrogen fuel gauges acted up. Three failed during Thursday's launch attempt; no one knows why.

Launch director Doug Lyons said yesterday's failure was similar to what happened before, except only one gauge malfunctioned this time.

"We would rather have launched today, obviously," Cain said. "This was going to be in the very least a good tanking test for us, and that's what it's turned out to be."

NASA quickly established an engineering team to come up with ideas on how to pinpoint and fix the problem. The engineers will report back to Cain and other managers tomorrow.

Most inspections and repairs could be carried out at the launch pad. If the shuttle has to be returned to its hangar for more invasive work, there will be no hope of launching in early January, Cain said.

The troublesome gauges, called engine cutoff sensors, are part of a backup system to prevent the shuttle's main engines from shutting down too late and running without fuel, a potentially catastrophic situation. They have been a source of sporadic trouble ever since flights resumed in 2005 after the Columbia disaster.

NASA had until Thursday to launch Atlantis with the European Space Agency's space station laboratory, Columbus. After that, unfavorable sun angles and computer concerns would make it impossible for the shuttle to fly to the international space station until next month.

Despite objections from some engineers, NASA tightened up its launch rules for yesterday's attempt in hopes of getting Atlantis off the ground by the week's end.

Not only did all four of Atlantis's fuel gauges have to work yesterday - until now, only three good gauges were required - but a new instrumentation system for monitoring these gauges also had to check out. NASA also shrank its launch window from five minutes to one minute for added safety.

Two groups of NASA engineers recommended the flight be postponed and the fuel gauge system tested.

But they did not oppose a launch attempt yesterday when it came time for the final vote.

Shuttle Commander Stephen Frick was closely involved in the decision process, officials said. Frick and his six crewmates departed for their home base in Houston late yesterday.