From: invalid@nospam.com   
      
   Hmm...i still don't see what's so wrong with RTG's? They are cheap,   
   reliable and have high energy density. Is there a ban on using RTG's or   
   what?   
      
   Gordon D. Pusch wrote:   
   > 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   
   >   
   > perl -e '$_ = "gdpusch\@NO.xnet.SPAM.com\n"; s/NO\.//; s/SPAM\.//; print;'   
   >   
   >   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)