Mission managers are working the fuel-sensor issue today, to see if they can get Atlantis, with the ISS’s Columbus Module aboard, on orbit tomorrow. NASA reports:

Managers to Discuss Atlantis Launch Today

Space shuttle Atlantis on launch pad 39A at NASA's Kennedy Space Center in Florida. NASA PHOTO NO: KSC-07PD-3585Dec. 7 - 8:45 a.m. EST
The launch of NASA’s space shuttle Atlantis will take place no earlier than Saturday, Dec. 8, at 3:43 p.m. EST. Thursday’s scheduled liftoff from NASA’s Kennedy Space Center, Fla., was postponed because of a problem with a fuel cutoff sensor system inside the shuttle’s external fuel tank.

The fuel cutoff sensor system is one of several that protect the shuttle’s main engines by triggering their shut down if fuel runs unexpectedly low. Launch Commit Criteria require that three of the four sensor systems function properly before liftoff.

Space Shuttle Program managers will hold a Mission Management Team meeting Friday at 2 p.m. to discuss the issue and determine the steps necessary to start a new launch countdown. A news conference will be held at about 5 p.m. after the meeting’s conclusion.

On Thursday morning, two of the four engine cutoff, or ECO, sensors inside the liquid hydrogen section of the tank failed a routine prelaunch check. Following the launch postponement, the tank’s liquid oxygen and liquid hydrogen were drained. While the tank was being emptied, engineers monitored and collected data on the liquid hydrogen sensors that failed. During that process, another sensor gave a false reading, indicating that the tank was “wet,” when it was dry. All ECO sensors are now indicating dry as they should be.

During Atlantis’ 11-day mission to the International Space Station, the shuttle and station crews will work with ground teams to install and activate the European Space Agency’s Columbus laboratory. The new lab will expand the station’s scientific research capabilities.

Media Resources
› STS-122 Press Kit (15 Mb PDF)
› STS-122 Fact Sheet (7.6 Mb PDF)
› STS-122 TV Schedule
› ECO Sensor’s Morning Press Briefing (Real Player Video)

Engine Cutoff (ECO) sensors graphics:
› LH2 ECO Sensor Locations
› Overall Schematic of ECO and Liquid Level (Point) Sensors
› Orbiter Avionics Bays
› Orbiter Aft Avionics Bays
› Functional Block Diagram of Point Sensor Box
› Exploded View of Point Sensor Box

More pics here and here. Local news videos here. Discussion here. News Resources here. Check the links at right for play-by-play and NASA TV.