From: mikecombs@nospam.com_chg_nospam_2_ti.retro.com   
      
   "Fred J. McCall"  wrote in message   
   news:mqgg31h7rpko6f095sad8upcj5cit26itc@4ax.com...   
   > wbogen@visteon.com wrote:   
   >   
   > :I believe the lighter the molecule in the exhaust, the more efficient   
   > :the engine?  If so, it might be better to make pellets of silicon (MW=   
   > :14) as we process the asteroid, charge them, and accelerate them using   
   > :an electrostatic engine.  Oxygen has a molecular weight of 16, would be   
   > :rather corrosive in a high-temp exhaust, and is more useful than   
   > :silicon for other purposes.   
   >   
   > But do you really want to be spraying what are essentially high speed   
   > bullets around where they can eventually hit other spacecraft?  Better   
   > something that isn't solid for your 'exhaust'.   
      
   Yes, but space is already criss-crossed with high-speed micrometeoroids.  So   
   the only sensible question that needs answering is are we making a   
   significant contribution to an already-existing problem.  At many levels of   
   scale, the answer is probably "no".   
      
   That said, I remember that in the "High Frontier" plan, it was proposed that   
   mass-drivers start out using pelletized Space Shuttle ET's for their   
   reaction mass, but at a fairly early point switch over to locally-produced   
   oxygen, which would vaporize on release.  So the impression that I get is   
   that it's not an issue to be disregarded, but it's not a big issue.   
      
   --   
      
      
   Regards,   
   Mike Combs   
   ----------------------------------------------------------------------   
   Member of the National Non-sequitur Society.  We may not make   
   much sense, but we do like pizza.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)