Expedition 18 Commander Mike Fincke and Endeavour Mission Specialist Don Pettit have proven their knack for detailed maintenance work during previous stays at the International Space Station and have once again put their skills to use.

The Urine Processor Assembly (UPA) inside the Water Recovery System (WRS), which recycles condensate and urine onboard the station, has experienced several shutdowns during testing. Engineers believe motion of the centrifuge caused physical interference within the UPA, resulting in increased power draw and temperatures.

Fincke and Pettit removed grommets from the UPA and hard-mounted it into the WRS rack. The grommets were serving as isolators to dampen vibrations from the centrifuge, but might have been allowing too much motion and causing the interference. Mission Control has been monitoring the UPA's operation and it has been running normally for two hours without prematurely shutting down.