NASA: Astronauts' urine clogs water recycling system on ISS

BEIJING, Jan. 13 -- Astronauts' urine is clogging water recycling system on the International Space Station, according to British media reports Wednesday.

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Flight engineer Mike Barratt (L) and Commander Gennady Padalka (R) work with cables on the docking antenna during their spacewalk from the International Space Station in this image from NASA TV June 5, 2009.

NASA engineers at the Marshall Space Flight Center in Huntsville, Alabama, who are investigating a problem with the system, believed the cause was a high concentration of calcium in the astronauts' urine.

The 250 million- U.S. dollar-system was set for processing urine into clean water for drinking.

However, scientists did not know whether the high calcium concentration is due to bone loss, a consequence of living in a zero-gravity environment, or other factors.

"Folks had good knowledge of the content of the urine going in, but the chemistry changes as it works through the processor are not always understood," said Julie Robinson, a scientist working on the project. "There are a lot of parameters including urine calcium and pH (acidity) that everyone is looking at."

The 100 billion-dollar-space station project involving 16 nations has been under construction 220 miles (about 354 km) above the Earth for more than a decade.

The meida reports said it was fully tested by NASA before the urine recycler was started up in November 2008.

Engineers are hoping to come up with a fix in time to fly replacement parts out on the shuttle Endeavour, which is scheduled for launch on Feb. 7 on a construction mission.