Article Posted on : - Nov 24, 2008

Expedition 18 and STS-126 crew members take a break to participate in interviews with reporters. Photo by NASA TV

WASHINGTON (BNS): The Urine Processor Assembly (UPA) inside the Water Recovery System (WRS), which recycles condensate and urine onboard the International Space Station, has experienced several shutdowns during testing.

NASA engineers are of the opinion that the centrifuge caused physical interference within the UPA, resulting in increased power draw and temperatures.

The UPA was sent aboard Shuttle Endeavour to help astronauts recycle water for drinking purposes at a time when the station is preparing to house more crew members from next year.

NASA engineers said the UPA was restarted and ran for about 20 minutes before a sensor placed it in 'standby' mode, believing the unit was processing too much liquid. They shut down the UPA and restarted it, running for a brief time before sensors shut it down again to do a detected variance in the distillation chamber's centrifuge motor speed.

Ground experts continue to troubleshoot with the station's new UPA that ultimately will process urine, perspiration and hygiene water into drinkable water. Expedition 18 Commander Mike Fincke and Endeavour Mission Specialist Don Pettit have 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, NASA said.

However, the second part of the new WRS -- the Water Processing Assembly, continues to perform well, processing condensate for a sample that will be returned to Earth by the STS-126 crew.

According to the US space agency, astronauts Steve Bowen and Shane Kimbrough are scheduled to leave the station's Quest airlock on Monday at 1:45 pm, on the mission's fourth spacewalk and continue work on the station's Solar Alpha Rotary Joints (SARJ). Both of them will remove insulating covers on the port SARJ and Kimbrough will follow through with its lubrication. Bowen will finish tasks on the starboard SARJ to install the final trundle bearing assembly.

Bowen will install a multi-layer insulation blanket on the station's Kibo module that was removed during the first spacewalk. "The cover is associated with the Exposed Facility Berthing Mechanism on Kibo, which has since been remotely tested from inside station, and the cover can be reinstalled. During that testing, however, one of the four latches did not close properly and Bowen will help complete the checkout procedure in person," NASA said.

The tasks would include installing a television camera on the port truss and a Global Positioning System antenna on Kibo that will be used for Japanese cargo craft arrivals.