Rotating Mirrors

Ron,

I agree that humans are adaptable, but only to a point. I grew up
deep in the hills of Kentucky, where the sun rises sometime in mid-
morning, and the horizon is always visible, being the tops of the
surrounding mountains. When I moved to Central Kentucky, the flat
landscape drove me nuts. I still don't think flat, open areas are
truly habitable by humans, without psychological penalties. Maybe
people have somehow adapted to their unnaturally flat environments,
but I'm not sure their faculties have remained intact. And how they
can walk from place to place, without going up and down at steep
angles, still astonishes me.

Anyway, I've thought a bit more about the mirrored disk concept, and
it does have some appeal. Basically it's a Stanford torus, but with
highly aluminized mylar acting as disks, which cover the normally
open area between the torus and the hub. The mylar can be in full
vacuum, and in fact this might be preferable. At the hub, sunlight
is collected by parabolic dishes, which don't rotate or move a bit
throughout the year, other than the 1 rev/year to track the sun. The
light goes into fiber optic cables, which likewise don't rotate.
Each fiber head then shines the light onto the inside of the mylar.
In the morning, the heads shine the light almost horizontally
(relative to an occupant). The light bounces back and forth, losing
a bit of intensity with each reflection, till it comes down to the
torus. To an occupant living next to one of the mirrored walls, it
will look like the sun is rising over the top of his 'neighbors'
house. As the day wears on, the heads shine the light more and more
vertically, mimicing the suns arc through the sky. Then the light
makes an abrupt flip, and starts coming from the other side of the
hub, and reverses the process used for sunrise.

Each head is mounted along with a small group of other heads, and are
pivoted to move from a line parallel to the station's axis of
rotation, down to near 90 degrees, aiming directly down toward the
torus. All the heads in a group are nearly parallel, with a very
narrow beam spread. Ideally, this would be 1/4 degree, so a person
below would see light from the same head as they traverse an
equivalent of 1/2 degree of angle. Since the light is provided by a
multiplicity of heads, all nearly parallel, it should mimick sunlight
pretty well. If constraints are eased, you could opt for a 'big sun'
look. It should be pretty simple to ray-trace the concept, and also
figure out what coating to use as the top skylight of the torus to
provide a diffuse, blue-sky background, if required. A ray trace
would also show if the concept provides the look of a larger, island-
3 type habitat.

Some advantages of the concept are the ease and cost of assembly, the
ability to fine tune lighting levels, merely by aiming a certain
percentage of heads off target, into space, without having to move
the parabolic dishes in any way. The ease of generating a sunrise-
sunset cycle, which will naturally have lower intensity for the
longer, horizontal paths (may have to go to 98% reflective mylar).
The ability to alter the spectrum of sunlight, by having heads with
differing filters, which can be added or subtracted from the
circuit. The ease of stretching the mylar out, compared to a
multiplicity of adjustable mirrors. The ability to perform final
assemblies under office lighting levels, with only about 1% of the
parabolic reflectors in place. The parallel nature of the colletors,
so some lost dishes can just be compensated for by re-routing fibers
to other heads, instead of picking up a dark area, which would happen
with a normal island-3 type mirror structure. An easy transition to
nighttime, which would occur naturally as the fiber optic heads
finished their nearly horizontal sunset move, and changed to fully
parallel, shining the light out into space.

Just my thought for the day, and something to pick apart.

George Turner