CAPE CANAVERAL, Fla. (Reuters) - NASA will try to launch the space shuttle Atlantis as early as Jan. 24 on a delayed mission to deliver Europe's first permanent space laboratory to the International Space Station, mission managers said on Thursday.
But the next launch attempt was more likely to happen in early February, managers said in a conference call with reporters.
Launch attempts were postponed on Dec. 6 and Dec. 9 due to erratic sensor readings in the spacecraft's hydrogen fuel tank. NASA had hoped to try again on Jan. 10 but decided late last month that it would need more time to fix the problem.
Atlantis' crew, five Americans, a German and a Frenchman, are to deliver Europe's Columbus science laboratory module to the space station, ending a quarter of a century in which European space pioneers had to run their experiments on orbital outposts owned by others.
The erratic sensors, which operate like dipsticks to determine fuel levels, are part of an emergency system to cut off the shuttle's three hydrogen-burning main engines if the tank runs dry because of a leak or other problem.
Running the engines without fuel could cause their pumps to break and possibly trigger a catastrophic explosion.
NASA engineers decided the fuel sensor glitch resided in a plug-like connector that relays electrical signals from the sensors in the tank through wiring leading to the shuttle's engine compartment. They removed the suspect part and took it to the Marshall Space Flight Center in Alabama for analysis.
"Everything has to go exactly right for us to make the 24th," John Shannon, the deputy shuttle program manager, said during the conference call. He added that the shuttle was more likely to fly in early February.
The U.S. space agency is on deadline to complete 12 construction and resupply flights to the space station by Sept. 30, 2010, when the shuttle fleet is to be retired.
Space Shuttle Atlantis at the launch pad on December 6.
NASA has announced that the launch of Space Shuttle Atlantis, mission STS-122, will once again be postponed, this time until late January or early February. The reason behind the delay is believed to be a faulty connector that caused erratic fuel sensor readings during the previous two launch attempts in December.

Space shuttle program manager Wayne Hale gave January 24 as the earliest possible launch date, but stated that February would be a more realistic expectation. "I think it's much more likely that we'll be going to be ready somewhere in the February 2 to 7 time frame, given that we don't have any more findings as we go through our testing," Hale stated.

The initial launch date for the shuttle was December 6, but failed fuel gauges in the external tank forced the launch to be moved to December 9. The fuel sensors are part of a system to prevent the shuttle from running on an empty tank, which could cause pumps in the engine of break and possibly trigger a disastrous explosion. 

When the problem reoccurred, NASA ran a fuel test, which led them to believe the problem lied in the faulty connector. The connector was then removed from the tank and taken to Marshall Space Flight Center in Huntsville, Alabama, where it is currently undergoing extensive analysis and modification. The new connector is scheduled to be installed by January 10.

"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," deputy space shuttle program manager John Shannon said. "We're fairly confident that if the problem is where we think it is, that this will solve that."

The main objective of mission STS-122 is to deliver the European science laboratory Columbus to the International Space Station.