ATM: Keeping Dust off

[Andres.Dandler.97@Alum.Dartmouth.ORG (Andres Dandler 97)]

Hello!

I was chatting with a friend of mine about the 16" 
open-truss dobsonian that I'm building.  I intend to use it 
in a very dry place, slightly windy.  I don't think I 
wan to use a shrowd, as I consider them ugly windsails.

I know dust on the mirror doesn't really detract from 
performance, but we kicked around some ideas, and I would 
appreciate some input.

1) To avoid dust from getting to the mirror, my friend 
suggested lining the insides of the mirror box with a 
dielectric material.  This material would attract dust that 
would otherwise fall on the mirror.

2) Pushing that idea a little further, he suggested making a 
series of "dust attractors" and lining them up around the 
mirror.  Each of these would consist of a needle stuck on a 
piece of cork, with thin wire wrapped around the cork.  A 
current going through the wire would produce a magnetic 
field that would attract dust to the needles (instead of 
letting it fall on to the mirror).

3) I'm planning on having a little fan in the back to help 
the mirror reach thermal equilibrium.  What if I put a 
filter in front of the fan and designed it so that the clean 
air avoids dust from getting to the mirror in the first 
place?  Here's a sketch, with the scope pointing at the 
zenith:


_______________________
|                      |
|___               ____|
|    ______________    |
|   |___mirror_____|   |
|                      |
|________     _________|
          ^^^^

The ^^^^ is the fan, pushing filtered air in.
The outside rectangle is the mirror box.
The two ___ on the sides, around and on top of the mirror, 
are sort of like a baffle, to push the clear air towards the 
center of the mirror.  The idea is that the air would go 
around the mirror on both sides, then head towards the 
center, and then head upwards at the center, more or less.

Any comments?  I know this may all be unnecessary, but 
brainstorming is fun anyway!

I guess one problem I see is making the electrical systems 
of (1) and (2) pick up only the dust that would have 
_otherwise_ fallen on the mirror, and *not* dust that would 
otherwise have stayed in the air (or on the ground!).

Cheers,

   -Andres