NASA on Thursday delayed the flight of space shuttle Atlantis until late January or, more likely, February to replace a suspect connector in the fuel tank. The connector is believed to be responsible for back-to-back launch postponements last month.
Deputy shuttle program manager John Shannon said the mission to the international space station is off until at least Jan. 24.
"Everything has to go exactly right for us to make the 24th," he said.
Shannon said it's more likely that the launch will move into February. The shuttle almost certainly would have to wait until a Russian cargo ship is launched on Feb. 7 and docks two days later.
Atlantis was poised to lift off in early December with a European space station lab named Columbus but fuel gauges in the external tank failed late in the countdown.
The problem reoccurred during a second launch attempt, prompting NASA to conduct a fueling test just before Christmas. That's when the trouble was traced to a connector that feeds wiring through the wall of the fuel tank. The circuitry runs between the fuel gauges in the bottom of the tank and the space shuttle.
The fuel gauges are part of a critical safety system to prevent the shuttle's main engines from running on an empty tank, and have malfunctioned off and on for more than two years. Engineers suspect a design flaw.
NASA removed the external portion of the suspect connector, along with some plugs, over the weekend. It will be another two weeks before the parts are fully analyzed, mimicking the super-cold conditions of fueling, Shannon said.
In the meantime, engineers will replace the external connector and make modifications — essentially soldering pins and changing the material of socket inserts.
"What we're doing ... is addressing what we think is the most probable cause, and there's a lot of information that points to that connector and that this is the right design fix," Shannon said.
Shannon would not estimate how long the delay might be if engineers determine that the interim solution is not enough or something else is at fault.
NASA requires at least five weeks between shuttle launches, which means that a flight by Endeavour to the space station, carrying up the first part of Japan's massive lab, will not occur Feb. 14 as planned.
Until a firm launch date is set for Atlantis, NASA will not address the timing of subsequent flights, Shannon said.
NASA faces a 2010 deadline for retiring its three shuttles and completing the space station.