XPost: sci.space.policy   
   From: henry@spsystems.net   
      
   In article ,   
   Alex Terrell  wrote:   
   >> Converting the laser beam into heat is no big deal in priniciple, but then   
   >> you run into the inefficiency of heat engines, and the need to get rid of   
   >> a lot of waste heat with a radiator system.  Solar arrays are easier.   
   >   
   >I agree solar arrays are easier, but you have 20% efficiency of the   
   >array and 90% efficiency of the motor = 18%...   
      
   Note that for a well-chosen laser wavelength, the conversion efficiency of   
   simple solar cells is 50%+.  The reason the efficiencies are so cruddy   
   when working from sunlight is the huge spread of photon energies.   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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