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While one of the crew was using the Russian-made toilet last week, the toilet motor fan stopped working, according to NASA. Since then, the liquid waste gathering part of the toilet has been working on-and-off.
Fortunately, the solid waste collecting part is functioning normally. Russian officials don't know the cause of the problem and the crew has been unable to fix it.
The crew has used the toilet on the Soyuz return capsule, but it has a limited capacity.
They are now are using a back-up bag-like collection system that can be connected to the broken toilet, according to NASA public affairs officials.snip
The 7-year-old toilet has broken once before but not for as long a time, said Johnson Space Center spokeswoman Nicole Cloutier in Houston.
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Discovery's main payload, a 32,000-pound Japanese laboratory addition, is so big that the shuttle's boom sensor system had to be removed to make room for the lab.