From: schillin@spock.usc.edu   
      
   alexterrell@yahoo.com writes:   
      
   >Henry Spencer wrote:   
   >> In article <1108143123.041040.288750@g14g2000cwa.googlegroups.com>,   
   >>   wrote:   
   >> >> the problem is not the solar cells but the structural dynamics of   
   >> >> enormous lightweight solar arrays...   
   >> >> ...Solving either in the next 20 years is conceivable, but not   
   >> >> a small project...   
      
   >> >But if you have lots of ion thruster, you can have lots of solar   
   >> >arrays, each flying independently, powered by four ion thrusters.   
      
   >> If they're connected by cables or structural elements, they are *not*   
   >> flying independently, and the dynamics problems have *not* gone away.   
   >>   
      
   >As long as the electrical cable is not taut, they are flying in   
   >formation, but exerting no force on each other.   
      
      
   The electric cable can only be "not taut", if the cable is massless   
   and/or the spacraft are not accelerating.  Otherwise, the cable is   
   under at least enough tension to supply the force accelerating the   
   mass of the cable.  While that force may be small, if the other   
   part of your system is a swarm of middling large but featherweight   
   gossamer structures, it's enough.  Henry is right, this is a Hard   
   Problem.  Almost certainly harder than making one huge solar array,   
   and that's not easy.   
      
   There may be some merit to a swarm of modestly sized flying solar   
   arrays using *beamed* power transfer, whether microwave or laser,   
   and I have seen the idea proposed here and there.  But it also is   
   rather beyond the state of the art.   
      
      
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