XPost: sci.space.history   
   From: andrew.gray@dunelm.org.uk   
      
   In article <64c0d119.0401211611.6268c84e@posting.google.com>,   
   Explorer8939 wrote:   
   > i'm not entirely sure what supplies bound the Soyuz TMA lifetime,   
   > other than the container used for the toilet gets filled after 4 days   
   > use. Other than the toilet, most other systems on TMA are similar to   
   > those used for the multi-week missions back in Soviet times. As late   
   > as Soyuz T-13, Soyuzes were used to support crews for more than a   
   > week.   
      
   I'd assume it's a simple consumables issue, but I don't know. Jim?   
      
   (There is a hardware constraint to the total lifetime, which is why   
   Soyuz get exchanged by taxi flights - seals (in the fuel lines?)   
   degrade, and can't be totally trusted after about six to eight months -   
   but I'm not aware of any similar ones which would only be relevant when   
   powered on. The LEM had something similar; once it was fuelled, it had   
   to be used within a set timeframe lest the fuel lines corrode)   
      
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   -Andrew Gray   
    shimgray@bigfoot.com   
      
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