From: nuny@bid.nes   
      
   On Tuesday, April 18, 2017 at 5:54:05 AM UTC-7, WaywardHorizons wrote:   
   > Though, wouldn't it be somewhat easier and cheaper to use some kind of laser-   
   > pushed lightsail?   
      
     I'm in agreement with Mr. Anderson in being a bit anxious about how well the   
   launch laser will be maintained during a long trip. Leaving your engine at   
   home means you don't have to carry fuel, but somebody else has control of the   
   throttle.   
      
     Suppose there's a big change at home and the whole idea of space   
   colonization falls out of favor or they decide they need that laser for   
   something else, or there's a natural disaster that breaks the laser just when   
   you need it most?   
      
   > And how much would the "seed module" mass, anyhow?   
      
     Look at the endgame and work backwards. Your slowship has arrived in orbit   
   of the colony world, and the A. I. "Captain" has woken all the adult crew. How   
   much stuff do they have to land, and how much land surface will they have to   
   "tame" in order to    
   plant crops and set up whatever they want to set up, like habitats and   
   whatnot? Does the ship stay in orbit or will it be landed and cannibalized for   
   parts and materials? It sure won't make a return trip until the colonists can   
   do maintenance and refuel    
   it, and it may take a hundred years before they can afford to do that.   
      
     Is the colony supposed to begin and remain high-tech or are these "pioneers"   
   who are expected to roll off a lander in Conestoga wagons and make their own   
   way?   
      
     Once you know the payload mass and trip distance and duration you can start   
   thinking about total ship mass at launch.   
      
   > > Also, what's your setting? Is it out world, Earth, or something else?   
   > It's Earth and stars within ~1500 light years. Though I intend the seedship   
   to   
   > have been from a completely different species.   
      
     Ah, okay. Well, another species may have completely different politics and   
   such so a launch laser system may remain reliable for such a long trip (I   
   wouldn't trust humans to stay on task that long).   
      
     An alien species idea of "planting a colony" may be somewhat different from   
   ours too, but unless it's the kind of "ensure species survival at all costs"   
   mission Mr. Anderson mentions, I'm guessing they will want to give them at   
   least some higher tech.    
   If it's a last-ditch thing then throwing them naked on the surface of a more   
   or less livable planet and letting them wing it from there is acceptable, I   
   suppose.   
      
      
     Mark L. Fergerson   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)