Alternative Island 3

Well, I threatened you guys... I mean I PROMISED you guys
another post, and here it is. ^_~

--- In spacesettlers, "improbableman" wrote:

> A few additional caveats:
>
> "The Icarus Problem"
> Human powered flight in the near-zero grav region becomes
> problematic when you place the intense sunlight at the center. The
> issue is that colony gravity is a linear inverse with proximity to
> the center, and light intensity is inverse square. Light intensity
> increases faster than gravity decreases, althought this problem
> also exists in colonies lit from the opposite side. That's
> actually worse, because you get equal sun intensity from all sides
> at the colony center, like a rotisserie chicken.

I think the idea is that, by the time the like got to the cetral axis
from a window, it would be dispersed/attenuated enough to not be a
ploblem. But I think you are on to something here, in that the
standard Island Three would have light intensities of what, three or
four thousand wats per square metre at the central axis? Four times
what it is at the valley surface.

> Solution, restrict flight to morning, evening, and night, when
> the sun is filtered.

Alternate solution: Place the "light emitters" 500 metres away from
the central axis, have four of them, and string a thin (but close-
woven) net from each to the other, and fly any time of the day or
night you like. You are now flying "above the sun," and have a 1,000
metre by 1,000 metre by 20 MILE flying volume (as well as a safety
net to make sure that you stray into neither higher-G areas or into
the blast of sunlight).

> That being said, if all that you need is gravity 1/6 the Earth's, a
> properly shaded craft could operate closer to the sunline. Mount
> the opaque wing above the pilot, and you have a stable design that
> protects the operator from the sun.
>
> "Dock? What dock?"
>
> In my approach, one of the colony endcap hubs would be taken
> up by the sunlight reflectors. This eliminates half the docking
> access to the colony. This is not neccessarily a bad thing.

Well, you now have a square kilometre of docking area at the endcap.
Should be big enough for docking.

> Having only one dock means that there are less airlocks to
> maintain, maybe less rotating fluid seals. Only one transport hub
> is needed, so security can operate more efficiently. If the
> transport system is designed well, and the colony is not
> disproportionately scaled up, one docking port should suffice for
> all exchanges with the exterior.

Probably.

> "Look out below!"
>
> Having any sort of facilities at the center of a cylindrical
> colony is often considered too great a risk, with the possibility
> of falling objects striking people or property below. This is a
> risk in all major cities on Earth, and appropriate precautions are
> taken.

That net should take care of most falling objects.

> However, the way objects fall in a centripetal system is different
> than the way they fall in a gravitational one.

http://lifesci3.arc.nasa.gov/SpaceSettlement/teacher/materials/ringwor
ld/ringworld.html
For thrown or falling objects in a rotating environment.

> Say, for instance, that you are a bolt. You come loose

"I don't want to be a bolt!" - Hoshino Tetsuro, Galaxy Express 999

and it may well be different given the changes I have proposed... or
not, as the case may be>

> That should preempt a few questions. I'm going to sleep.

Now THAT sounds like a good idea!

Xenophile (who will probably be up another couple of hours, anyway)