Excerpt Reuters report "NASA halts test of space station urine recylcer":
NASA called off tests of the International Space Station's urine recycler on Sunday after problems developed and revamped plans for Monday's spacewalk to fix an improperly installed cargo platform attachment.
Flight directors also repositioned the station and the visiting space shuttle Discovery to avoid a piece of space junk, which was expected to come too close during Monday's spacewalk, the last of three during Discovery's mission.
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At speeds exceeding 17,500 mph, shards as small as a fleck of paint have enough energy to damage or destroy spacecraft.
Also Sunday, engineers were trying to figure out why a water purification system that recycles urine and condensate into drinking water was not working properly.
The Discovery crew delivered a new distiller for the centrifuge-type device that was successfully tested without liquids on Saturday. Problems developed during the first test run Sunday using urine.
"Once you closed valve 3 it didn't seem to flow," station commander Mike Fincke radioed to ground controllers.
"I have no idea why that could be, so good luck with the trouble-shooting and we're standing by to answer any questions or be of any use."
NASA wants to have the urine recycler working before expanding the station's live-aboard crew from three to six members in May.