Mission Control Center, Houston, Texas

HOUSTON - As the STS-126 and International Space Station Expedition 18 crews readied for the fourth and final spacewalk of the mission, NASA managers decided to extend Endeavour's stay by one day with landing now scheduled for 12:18 p.m. CST Sunday.

The extra day was approved in order to provide the crews as much extra time as possible for any continued troubleshooting on the new Water Recovery System. Expedition 18 Commander Mike Fincke continued work on the Urine Processor Assembly's (UPA) distillation hardware. He installed two more bolts to hard-mount the distiller assembly section of the UPA in place, which may further reduce vibrations that engineers believe are causing the UPA to prematurely shut down.

Once complete, they added stored urine to the UPA and started another processing cycle at 7:06 p.m. CST. Engineers hope the maintenance performed will enable the UPA to run for its full four-hour processing time. The astronauts also set up a wireless instrumentation system to track vibrations of the UPA.

Meanwhile, outside the orbiting complex, astronauts Steve Bowen and Shane Kimbrough wrapped up the final spacewalk of the mission. The spacewalk began at 12:24 p.m. CST and lasted six hours, seven minutes, ending at 6:31 p.m. CST. The first priority was to complete all the remaining tasks associated with lubrication of the Solar Alpha Rotary Joints as well as other station assembly tasks. Thin lines of lubricant were observed on the port SARJ race ring with some minor wear where the trundle bearing assemblies are riding. Additional lubrication was added as a preventive measure against further degradation despite the unit working normally.

Bowen returned to the starboard SARJ to install the final trundle bearing assembly. All 12 now have been replaced. At approximately 4:30 a.m. CST Tuesday, the ground team plans to initiate an auto track of the newly cleaned and lubricated starboard SARJ to assess the performance and overall health.

Bowen retracted a berthing mechanism latch on the Japanese Kibo Laboratory and reinstalled its thermal cover. He also installed a video camera on the Port 1 truss and attached a Global Positioning System antenna on the Japanese Experiment Module Pressurized Section.

Endeavour's crew is scheduled to go to bed at 11:55 p.m. CST and to be awakened at 7:55 a.m. CST Tuesday. The next shuttle status report will be issued at the beginning of the crew day, or earlier if events warrant.

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