XPost: sci.astro.amateur   
   From: no-spam@invalid.com   
      
   In article ,   
    "Glenn Mulno"  wrote:   
      
   > "richard schumacher"  wrote in message news:no-spam-   
   > > >   
   > > > I am a bit puzzled why they only made the probe last the few short   
   > > > hours after it detached from cassini. They could of built a better   
   > > > battery when Voyager I is like 28 year and still going. I know it is   
   > > > like -300F and mechanical things won't operate long in that harsh   
   > > > environment. Assuming the probe could survive the environment it would   
   > > > of been nice to be able to tap it for everything possible.   
   > >   
   > >   
   > > The issue is how long the orbiter is in range to relay data from Huygens   
   > > to Earth.  It's only a few hours, so a longer-life battery for Huygens   
   > > would have been pointless.   
   >   
   > If that were the "only" reason then I would disagree.  Cassini will be   
   > passing by Titan again in a few weeks.  I would think they could have held   
   > data and then blasted it at the satellite each time it passed.   
   >   
   > However, as I understand it that is not really why they kept the life to   
   > only a few hours.  I think it had more to do with just getting it down   
   > safely, the weight of the probe on Cassini, cost, and probably just the   
   > general expectation that  conditions were not favorable to the life of the   
   > unit being long.   
      
   A lifetime of weeks would have required nuclear heaters at least, and   
   perhaps a nuclear thermal electric source as well.  That means more   
   mass, probably more then anyone wanted to pay to send.   
      
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