From: g_d_pusch_remove_underscores@xnet.com   
   Copy: mapsemdnes@hotmail.com   
      
   mapsemdnes@hotmail.com (groutch) writes:   
      
   > I was wondering why NASA accepts a shortened life for the Mars Rovers   
   > due to "dust build-up on the solar panels".   
   >   
   > Is cleaning them beyond their rocket scientists ?   
      
   Cleaning hyper-fine dust off of darned near _anything_ is MUCH harder   
   than you apparently realize. NASA was unable to find a good way to   
   clean hyper-fine moondust off the Apollo astronaut's space-suits,   
   so that dust accumulation was already causing severe problems in the   
   spacesuit glove/wrist joints after only a few days --- and mars dust   
   appears to be even "stickier" than moondust, perhaps because there is   
   just _barely_ enough water in it to make it "muddy."   
      
   Nor is dust accumulation the only "energy crisis" faced by the rover.   
   Rechargable battery technology still pretty much sucks; even after over   
   100 years of research, the performance of most rechargable batteries   
   degrades significantly after only a few hundred or so deep discharge cycles   
   (which is one of the reasons we _still_ don't have practical electric cars!_).   
   Even if we _could_ find a way to clean the solar panels effectively,   
   the rover's rechargable batteries will gradually lose the ability   
   to store enough of the excess energy produced by the solar panels during   
   daylight to allow the rover to survive the cold of the martian night...   
      
      
   -- Gordon D. Pusch   
      
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