Colony Illumination

Ed Schonert wrote:

> I believe consensus opinion is for the "radiation-shield 'cave'
> that doesn't rotate" (ref Ian Woollard's 7-22 Radiation Fatigue?
> comments). He's saying a conical glass cylinder down axis of
> colony cylinder lets in light reflected from a large concave mirror.
>
> Since incoming beam is converging

Not quite sure why you say that; it very much could/should be
parallel.

> I assume that is why the
> conical shape is preferable over true cylindrical for this incoming
> light container.

I wasn't thinking that clearly about it. Conical would let the
light through at an angle and would be as strong or stronger.

> Wouldn't there be a series of inclined mirrors on
> inside of glass cone required to re-reflect light out to entire inside
> of colony cylinder?

I'd expect you'd want the mirrors on the vacuum side, because
they stay clean. Cleaning windows is easier

> It would have been far easier to just put a
> window @ center of end cap of colony cylinder.

Yes. On reflection you're probably right. It might be
a good idea to form it as an interior dome however, that
way you get the compression effect I mentioned before, rather
than try to make it flat.

Also, you could then put the mirrors in a cone shape, inside
the colony.

> However the
> fear of a stray meteor "busting through" window makes me favor
> this window in form of internal cone-cylinder.

I think O'Neill was right about this, it's not all that
likely. The odd window will break, but if you engineer them
right it should be ok. You'd want to fix it, but it's not
that bad. Actually that's another advantage- the windows
are smaller.

> Are we sure Panama Bob's July 8 suggestion to use fibre-optic
> to let in sunlight wasn't more practical?

It can work, but it's a lot of fiber. Fiber is only really
transparent in the infrared; although I don't have the figures
handy for the transmission coefficient in the visible.

> I believe his idea was
> for the ~2+ meters of regolith to be placed with a lot of fibre-
> optic elements through it to let light right thru radiation shield.
> If colony assigned outside orbit of Saturn perhaps both the
> sources will be needed. If colony assigned around Venus
> perhaps we wont need the center window at all (use only fibre-
> optic light coming up through ground).

Don't particularly like... light pipes are ok I guess.

> Hallelujah - Praise Spacesettlers ! ! ! Ed S.
>

--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill