From: ericfenbyamanuensis@btopenworld.com   
      
   "Mike Miller"  wrote in message   
   news:5dcb47db.0402070618.701535a2@posting.google.com...   
   > "Jason Donahue"  wrote in   
   message news:<10261ee7mlb2p05@corp.supernews.com>...   
   > > "Mike Miller"  wrote in message   
   > > news:5dcb47db.0402010547.4522174@posting.google.com...   
   >   
   > > > How about a space elevator? Take a cable car to orbit.   
   >   
   > > Neat idea, but, IIRC, really, really tough to do with current   
   technology.  I   
   > > mean, how high up does your space elevator need to go, and how much mass   
   in   
   > > materials would that take?   
   >   
   > It's less an issue of "how high up" than "how far down from   
   > geosynchronous orbit." An orbital elevator is a structure in geosynch   
   > orbit.   
   >   
   > Materials mass is probably in the megatons or more, especially if you   
   > include the anchor asteroid that helps keep the elevator under   
   > tension.   
   >   
   > But you probably need to get less stuff into orbit to move an asteroid   
   > than you do to build an elevator, and you avoid the bother of repeated   
   > launches with nuclear rockets or inventing new kinds of reactionless   
   > physics.   
   >   
   > Mike Miller, MatE   
      
   No good. By the time we are clever enough to build a space elevator NEO will   
   be full of junk and bits of builders rubble. Impacts with the structure   
   would be only a matter of time. Any such impact would at a stroke treble the   
   amount of junk in that particular orbit then every subsequent orbit would be   
   a  destructive hailstorm of shrapnel. If the elevator ever broke up then NEO   
   would be unuseable because of the scrap metal/matrix material and miles of   
   the said scrap metal would fall across several different nation's   
   territories.  It's increasingly worrying for the Shuttle (which already   
   orbits with it's engines forward) and NEO must be cleaned up before we can   
   even plan more extensive use of it.   
   For these reasons and others I don't think an elevator will ever be built.   
   I want a starship, or at the very least a nuclear-powered platform capable   
   of scooting about the solar system and which is powered by some sort of   
   drive which does not depend on mass ejection. Perhaps we should put manned   
   space exploration away for fifty years while we learn how to walk.   
   In the meantime robots are just great and getting greater.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)