Re: starship-design: scoops and sails and something to push against.

[Kevin Houston <kevin@urly-bird.com>]

Lee,

It seemed to me that you were talking about gathering the hydrogen in
toward the ship, then expelling it again.  ( fig. 1.)  (Note missed
hydrogen)

                                                    
                                                    
  H    H    H   H   H     H   H                           
   \    \ H |   |   |    /   /                          
    \    |  |   | H |   |   /                           
     \    \  \  |  / H /   /     H                       
  H   \  H | |  |  |  | H /                             
       \   \ |H |  |  /  /                              
        \   | \ | /  |  / H       H                        
   H     \  \ | | | /  /                                 
          \  || | ||  /                                     
 H   H     \  V | V  /     H     H                         
            \ \ | / /   H                                 
  H    H     \ \|/ /                                      
              \ | /           H                         
               \|/                                     
               |||                                     
               [S]                                    
               [H]                                    
               [I]                                   
               [P]                                    
               |||                                     
               HHH                                     
               HHH                                     
               |||                                     
               VVV                                     


Whereas I am proposing this: (fig 2)
                                                    
                                                    
   H    H        H                                     
   |    |  H     |     H     H                            
   V    V  |     V     |     |                           
       H   V       H   V     V                           
       |       H   |     H                              
   H   V  H    |   V     |     H                         
   |      |    V      H  V     |                         
   V      V           |        V                        
                      V                              
   - - - - - -      - - - - - -    negative charges  
   -----------[ship]-----------                      
   + + + + + +      + + + + + +    positive charges  
   H    H        H                                     
   |    |  H     |     H     H                            
   V    V  |     V     |     |                           
       H   V       H   V     V                           
       |       H   |     H                              
   H   V  H    |   V     |     H                         
   |      |    V      H  V     |                         
   V      v           |        v                        
                      V                             

Where the dashed line is some sort of combination field conductor, and
energy collector.  I see this ship as a large saucer, with living
quarters toward the middle, and a very thin mesh of wires, and energy
collectors spread out along the periphery.  Rotation would keep the
whole thing stable, and spread out.  the above view would be from the
side.  Think of it as a giant version of starwisp, but instead of
reflecting the energy, the mesh collects the energy, turns it into
electricity, which supports an electric field of several megawatts
potential.  I suppose we'll need two meshes, one for the positive
charge, and one for the negative.  They only need to be separated enough
to prevent bridging.

I imagine the field must be pulsed to get any use out of it, but with a
"Sail" a few hundred kilometers across, we should find enough Hydrogen
to push against.  Not much, granted, but with a big enough field, we
should be able to make the hydrogen ions move fast enough so as to push
us in the the opposite direction.  

I think perhaps this would work better at higher speeds, where the
apparent density will increase.
                                                    

L. Parker wrote:
> 
> Kevin,
> 
> This is pretty much what Timothy and I were discussing. To clear up a few
> points for the rest of the list...
> 
> In order for an electromagnetic scoop to work, the particles that it
> "scoops" must be charged, or ionized, you cannot scoop a neutral particle.
> 
> The most common method proposed for creating charged particles is to beam a
> laser "fan" ahead of the ship. The photons impacting the interstellar
> hydrogen will create a hydrogen ion with a negative charge which can then be
> attracted to a positively charged scoop field.

Umm... Negative?  By stripping away an electron, wouldn't it be
positive?  If I'm wrong, then reverse the charges on the above drawing.

> 
> In this much at least your idea is good. It removes the mass of the lasers
> from the ship and you could actually use an uncollimated solar mirror which
> is much simpler.

mirror, really?  That would be better, but would it be strong enough at
light years distance?

> 
> However, the density of the scoop field and the energy required to generate
> it are still enormous. On board power generation would probably have to be
> several times larger than a small city's supply.

not if you are swimming in a sea of energy capable of ionizing hydrogen 
;)

> 
> Timothy,
> 
> How do you generate a field with a sharp boundary?
> 
> Lee

-- 
Kevin Houston http://www.lpmn.org/candidates/
Libertarian candidate for Congress - District 5