Work to modify hoses needed to route ammonia coolant to and from a new space station module is running on or ahead of schedule and the new lines should be delivered to the Kennedy Space Center in time for an on-schedule launch Feb. 7, officials said Wednesday.

The Endeavour astronauts speak with reporters at pad 39A today. Credit: Ben Cooper/Spaceflight Now

The shuttle and its six-member crew are tentatively scheduled for takeoff at 4:39 a.m. EST on Feb. 7 to deliver the new Tranquility module, or node 3, to the International Space Station. The multi-port module will be used to house critical life support equipment, a robotics work station and exercise gear that's currently located elsewhere in the lab complex.

NASA originally planned to attach Tranquility to the Earth-facing port of the station's central Unity module, but engineers decided to move it to the left side of the module to improve options for docking future commercial cargo ships and NASA's planned Orion crew transfer vehicle.

But connectors needed to circulate ammonia coolant to and from Tranquility were not correctly positioned, or "clocked," for Tranquility to be attached to Unity's left-side port. Long extension jumpers were ordered, but problems during recent pressure tests put the Feb. 7 launch date in doubt.

NASA managers ultimately decided to connect shorter flight-qualified hoses to solve the problem. As a backup, improvements were ordered to the longer hoses.

Endeavour spacewalker Robert Behnken said Wednesday work to ready the replacement hoses was ahead of schedule and should be delivered to the Kennedy Space Center in time for launch.

"We've been following these ammonia lines and the story associated with them for 13 months," he said. "I think folks paying close attention right now haven't really heard the entire story. So we've been watching them closely for a long time."

He said the crew flew to NASA's Marshall Space Flight Center in Huntsville, Ala., last weekend "to see the first line as it was coming together and actually put it on a test rig to make sure it was going to do the job that it was intended. We're expecting this Saturday to fly up and see all four lines in a pretty good configuration, pretty flight representative. Those lines, after that, will come down here to KSC for processing and installation into the orbiter."

"Right now, the schedule appears for that set of lines to be a couple of days ahead," he said. "Our original plan was to do our fit check and our opportunity with them next weekend, but they're ahead now and we'll be able to do that this Saturday, which is great news."

Credit: Ben Cooper/Spaceflight Now

Behnken and his crewmates - commander George Zamka, pilot Terry Virts, Kathryn Hire, flight engineer Stephen Robinson and fellow spacewalker Nicholas Patrick - flew to the Kennedy Space Center Monday to review launch pad emergency procedures and to participate in a practice countdown Thursday.

NASA managers plan to hold an executive-level flight readiness review Jan. 27 to assess Endeavour's processing and to set an official launch date. If all goes well, the shuttle countdown will begin Feb. 4.

Aboard the International Space Station, meanwhile, commander Jeffrey Williams and Max Suraev plan to strap into the Soyuz TMA-16 spacecraft Thursday and move it from the aft port of the Zvezda command module to the new Poisk docking module attached to the module's upper, or zenith, port.

On Saturday, the station crew will use the lab's robot arm to move a pressurized mating adaptor docking port - PMA-3 - from Unity's left-side port to the zenith port of the forward Harmony module. That will clear the way for Tranquility's attachment to Unity during Endeavour's mission.

After Endeavour's crew attaches Tranquility to Unity's left-side port, PMA-3 will be removed from Harmony and attached to the new module's outboard port.

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