U.S. & World News

CAPE CANAVERAL, Fla. (CBS) ― NASA on Sunday delayed the launch of space shuttle Atlantis until January after a gauge in the fuel tank failed for the second time in four days. NASA on Sunday delayed the launch of space shuttle Atlantis until January after a gauge in the fuel tank failed for the second time in four days.

NASA began fueling the shuttle at about 6 a.m., hoping that the gauges in its big external tank would work properly and allow launch controllers to proceed with an afternoon liftoff.

CBS News correspondent Peter King reports that all was going well until an hour into the refueling process, when one of the four fuel tank sensors gave a "dry" indication when there was actually fuel in the tank.

These sensors are part of the backup system that tells the shuttle's main engines to shut down before fuel runs out, says King.

The same problem occurred Thursday, when three hydrogen fuel gauges acted up, prompting the scrub of that day's launch. No one knows exactly what caused that problem, but shuttle managers had said they would halt the countdown and call everything off if any of the four fuel gauges malfunctioned.

Not only do all four of Atlantis' fuel gauges have to work - until now, only three good gauges were required - a new instrumentation system for monitoring these gauges also has to check out well. What's more, NASA has shrunk its launch window from five minutes to a single minute for added safety.

They will now drain the fuel tank in stages to see how the sensors react - that could give them some insight into the problem.

"In a way this could be a good thing," said NASA spokesman George Diller, adding that it "may very well help us get to the bottom of this problem."

NASA may try for another launch tomorrow.

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 following the Columbia tragedy.

With no idea what is causing the fuel gauges to fail every so often, any repairs would take days if not weeks. As a result, senior managers decided Saturday to alter its launch rules for this mission only, in hopes of getting Atlantis off the ground as soon as possible.

If the shuttle isn't flying by week's end, the mission will be delayed until January because of unfavorable sun angles and computer concerns.

Two groups of NASA engineers recommended that the flight be postponed and the fuel gauge system tested, to figure out what might be going on. But they did not oppose a Sunday launch attempt when it came time for the final vote.

Shuttle commander Stephen Frick was deeply involved with the decisions that were made, officials said.

Both the astronauts and flight controllers would have an added burden if multiple fuel sensors were to fail once the shuttle lifted off and a leak or some other serious trouble cropped up during the 8½-minute climb to orbit. They would have to override the system, and hobble to orbit or make an emergency landing.

Frick and his six crewmates - one of them French, another German - are set to deliver and install the $2 billion Columbus laboratory at the space station. It will be the second lab added to the orbiting outpost and Europe's entree to daily, round-the-clock scientific operations with astronauts in space.

(© 2009 CBS Broadcasting Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)