Technicians point to an area of space shuttle Atlantis' external tank sensors are located.

On Launch Pad 39A, technicians point to an area of space shuttle Atlantis' external tank where the engine cut-off, or ECO, sensors are located. The shuttle's planned launches on Dec. 6 and Dec. 9 were postponed because of false readings from the part of the ECO system that monitors the liquid hydrogen section of the tank. The liftoff date from NASA's Kennedy Space Center, Florida, is now targeted for Jan. 10, depending on the resolution of the problem in the fuel sensor system. Photo credit: NASA/Kim Shiflett