MARSHALL SPACE FLIGHT CENTER, Huntsville, Ala. - NASA engineers believe they have duplicated the failure mechanism that has plagued the space shuttle program with sporadic bad readings on engine cutoff (ECO) sensors in the orbiter's external tank.

The failure produced an intermittent open circuit in the pass-through connector that draws information from ECO sensors in the shuttle's liquid hydrogen tank.

This should allow NASA to try again Feb. 7 to launch STS-122/1E, when Atlantis will carry Europe's Columbus laboratory to the International Space Station.

Verification and testing will take another two weeks, but engineers believe the work done supports the theory that the super-cold temperatures of the liquid hydrogen produced the open circuit in two ways: When the tank was filled, the air around connector pins inside the wall of the tank apparently froze and produced an insulating layer in the connection. And when the tank contracted in the cold temperatures, the motion pushed the connection over the insulated space on the pin, breaking the circuit.

Stephen Cash, manager of the shuttle propulsion office here, said Marshall engineers sent the modified design to Kennedy Space Center, where engineers there made the modification in Atlantis' tank. The change involves soldering the connection together so it maintains integrity through the temperature cycle.

It'll take "the next couple of weeks" for additional testing and analysis of the results, Cash said. But unless something unexpected arises, that should clear this problem for Atlantis' launch.

The shuttle's four liquid hydrogen ECO sensors are designed to detect low propellant levels as a backup to cut off the three space shuttle main engines if vehicle computers try to continue and run the tank dry of fuel - an event that could cause an explosion. Different ECO sensor problems caused earlier delays in the STS-114, STS-115 and STS-121 launches in 2005-2006.