XPost: sci.space.science   
   From: someguy@somewhere.se.retro.com   
      
   Henry Spencer wrote:   
   > In article <421ebc7e$0$42486$75868355@news.frii.net>,   
   > Jim McCauley  wrote:   
   >   
   >>I realize that all spacecraft require some degree of radiation hardening...   
   >   
   >   
   > LEO satellites don't really need anything beyond error-correcting memory...   
   > and in an equatorial orbit, probably not even that.  (Almost all of the   
   > bit-flips in memory occur during passage through either the South Atlantic   
   > Anomaly or one of the auroral ovals, and an equatorial orbit encounters   
   > neither.)   
   >   
   This is a very optimistic statement! Bit flips may occur in memories   
   already when you are flying in a passenger aircraft across the poles.   
   IIRC the shuttle computers get a couple of hundred bit flips per mission   
   at 28 degrees inclination, even more at ISS orbit inclination.   
      
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