Rotating Mirrors

From: Gturner6PPC@... [mailto:Gturner6PPC@...]

I was wondering about some of Gerard K. O'Neil's designs for
cylindrical habitats. He shows mirrors extending out at 45 degrees,
to reflect sunlight in through the station's skylights. Since the
outer end of the mirror will be experiencing a very large number of
G's (1 plus twice the length/width ratio of the cylinder), isn't this
a design problem? Surely this has since been revised by someone.

One critic in Steward Brand's "Space Colonies" ripped into those mirrors
pretty good. Some of what he said was incorrect, but he was right about the
basic problem which you raise.

http://lifesci3.arc.nasa.gov/SpaceSettlement/CoEvolutionBook/JOHNH.HTML

Personally, I don't think the Island 3 mirror design would work as depicted.
But I don't consider it any big deal because there are other designs with
stationary mirrors which could easily be scaled up to the dimensions of
Island 3 (Bernal Sphere being one). The Stanford Torus has secondary
mirrors which rotate with the habitat, but should fair somewhat better since
they would be at about 1/2 G.

Anyone know of newer methods? I was thinking of a non-rotating
mirrored cone, with the amount of reflective material diminishing as
the diameter increases, to provide a consistent amount of sunlight
from one end of the station to the other.

I've been down that same mental route, but whatever one can propose will be
less natural-looking than what was desired. (For example, a sun that looks
normal at one end of the cylinder, but breaks up into a cluster of brilliant
moving "stars" as one progresses up the length of the cylinder. Another
possible solution is a cone with a "bugle flare". One would then have a sun
which was short and squat at one end of the cylinder, and long and thin at
the other. One might argue that this would be no big deal, though.

But bottom line, I'm more optimistic about designs that involve stationary
mirrors than mirrors which rotate with the habitat. And there are a number
of good ideas out there which can use stationary mirrors to recreate a
natural-looking sun in the "sky".

Regards,

Mike Combs

From:
Gturner6PPC@... [mailto:Gturner6PPC@...]
I was wondering about some of Gerard K. O'Neil's designs for
cylindrical habitats. He shows mirrors extending out at 45 degrees,
to reflect sunlight in through the station's skylights. Since the
outer end of the mirror will be experiencing a very large number of
G's (1 plus twice the length/width ratio of the cylinder), isn't this
a design problem? Surely this has since been revised by someone.

One critic in Steward Brand's "Space Colonies" ripped into those mirrors pretty good. Some of what he said was incorrect, but he was right about the basic problem which you raise.

http://lifesci3.arc.nasa.gov/SpaceSettlement/CoEvolutionBook/JOHNH.HTML

Personally, I don't think the Island 3 mirror design would work as depicted. But I don't consider it any big deal because there are other designs with stationary mirrors which could easily be scaled up to the dimensions of Island 3 (Bernal Sphere being one). The Stanford Torus has secondary mirrors which rotate with the habitat, but should fair somewhat better since they would be at about 1/2 G.
Anyone know of newer methods? I was thinking of a non-rotating
mirrored cone, with the amount of reflective material diminishing as
the diameter increases, to provide a consistent amount of sunlight
from one end of the station to the other.

I've been down that same mental route, but whatever one can propose will be less natural-looking than what was desired. (For example, a sun that looks normal at one end of the cylinder, but breaks up into a cluster of brilliant moving "stars" as one progresses up the length of the cylinder. Another possible solution is a cone with a "bugle flare". One would then have a sun which was short and squat at one end of the cylinder, and long and thin at the other. One might argue that this would be no big deal, though.

But bottom line, I'm more optimistic about designs that involve stationary mirrors than mirrors which rotate with the habitat. And there are a number of good ideas out there which can use stationary mirrors to recreate a natural-looking sun in the "sky".

Regards,
Mike Combs