XPost: sci.space.policy   
   From: joe@strout.net   
      
   In article ,   
    "Mike Combs"  wrote:   
      
   > > and the radiator mass needed   
   > > to reject all that extra heat,   
   >   
   > Undeniably true.  But I think one thing this issue hinges on is which is   
   > more expensive per sq meter: simple panels of aluminum tubing, or panels of   
   > PV arrays?   
      
   Well, it's the total cost that matters, not the cost per square meter.   
   Unfortunately that probably requires a more detailed analysis than we   
   can do here.   
      
   > > as well as severe constraints it imposes   
   > > on overall colony geometry, which can have serious impacts on your mass   
   > > budget -- for example, it would be hard-to-impossible to make much use   
   > > of natural light in a multi-deck design like Kalpana One.   
   >   
   > I would agree, but have a personal dislike for multi-deck designs.  They   
   > pursue a different design goal, which is "provide as efficiently as possible   
   > living area for X people".  I still have a fondness for O'Neill's original   
   > design goal, which was "recreate as closely as possible the most attractive   
   > parts of the Earth's surface".   
      
   Yes, this is a very insightful point.  To put it another way, O'Neill   
   was addressing the concern, "People won't want to live in a can."  He   
   pretty much took it as assumed that people could afford to do so if they   
   wanted to.  In my efforts, I'm generally trying to address the concern,   
   "people can't afford to build a can they can live in."  I take it as   
   assumed that people will want to if they can afford it.   
      
   Of course, O'Neill didn't wastefully make his designs expensive, and I   
   don't wastefully make mine unattractive.  But emphasizing one or the   
   other does lead to some different design decisions.   
      
   But getting back to the multi-deck designs, they don't necessarily have   
   to be less natural than, say, a torus.  For example, I've toyed with   
   (but not yet studied in detail) disk geometries that would have a true   
   image of the sky on each deck (the image is actually focussed through   
   long windows on the side wall).   
      
   I also think that we might actually be better off with an entirely   
   artificial sky -- that is, a smooth white surface with a series of   
   high-power, high-resolution projectors trained on it, like at a   
   planetarium.  This could show an Earthlike sky during the day (including   
   sunrises and sunsets), and at night, show you the real outside view.   
   Assuming the sky is sufficiently far away (say, 50 m or more), and the   
   projection is of sufficiently high quality, this would look as good or   
   better than real windows.   
      
   But I know, our gut tells us that this is a "fake" while windows and   
   mirrors are "real," and emotionally this is a significant difference.   
   It's hard to tell which one most people would prefer -- a realistic but   
   very unnatural sky, or an artificial but very natural-looking one.  Some   
   data points can be gathered from places like the Blue Bijou in   
   Disneyland, where you can eat under a twilight Louisiana sky, even at   
   high noon.  People know it's fake, but (in my experience) find it quite   
   pleasant -- and that's a roof only 3 m over your head instead of 50.  In   
   fact, by the time I'm done with lunch and emerge into the real sunlight,   
   I always feel a bit of a shock, as I had subconsciously forgotten that   
   it wasn't actually dusk.   
      
   Best,   
   - Joe   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)