Florida ? NASA called off Thursday’s launch of space shuttle Atlantis after a pair of fuel gauges in its big external tank failed to work properly, a recurring problem ever since the Columbia disaster.

Shuttle managers said the next launch attempt would be no earlier than Saturday. Atlantis is loaded with a European space station lab, Columbus, that has been waiting for years to fly to the international space station.

After meeting well into the evening, shuttle managers decided to forgo a Friday launch attempt to give engineers more time to figure out what was wrong and, quite possibly, work around the problem.

Preliminary indications were that the problem might be with an open circuit rather than the gauges themselves – perhaps a spliced line or bad connector – which would be easier to fix.

Two of the four engine-cutoff sensors failed a standard preflight test Thursday morning as Atlantis was being fueled with liquid hydrogen; three are required to provide accurate readings in order to proceed with a launch. NASA is considering the possibility of flying with fewer sensors working.