Different type of habitat

Mike,

>From: spacesettlers@yahoogroups.com
>[mailto:spacesettlers@yahoogroups.com
] On Behalf Of Darren
>
>SNIP
>
>> ... the spin would need to be maintained because of drag
>
>That's the problem that I have with the idea. I don't know what the air
>drag would be on a rotating cylinder 4 miles in diameter and 20 miles
>long, but I imagine it would be tremendous and that the energy
>requirements to overcome it every second of the structure's existence
>would probably not be economically sustainable. I think the only reason
>why keeping such structures rotating in space is considered at all
>viable is because of the assumption that this rotation is taking place
>in vacuum.

Agreed, there is a lot of work being done with surfaces with micro sized
bumps and pits designed to create micro vortexes to help reduce drag and
other work being done on laminar flow but even if the drag could be reduced
to the maximum possible there is still going to be a huge amount of energy
being expended and that will translate as heat, a lot of heat. While it is a
nice idea I do not see it as a viable option. The spinning version with a
vacuum at the axis of rotation is a much better way to go, if you are
building something this size.

Of course, a smaller version could be useful, bring it down to a
non-rotating sphere a few tens of kilometres wide or even up to a hundred or
for some things, two hundred kilometres and things change. A space based
manufacturing facility is one of the primary goals we should be working
towards. You could have a few counter rotating rings around the equator if
you really wanted (though a separate structure would most likely be a better
way of doing it) a place where you had spin-grav. The thing is such a huge
pressurised space would have few uses (other than building new habitats)
that couldnt be better done in a number of smaller structures.

Putting aside a place to hold a cluster of smaller habitats, there is one
other use for a non-rotating cylinder/sphere that is a thousand kilometres
wide (ignoring the expense). Scatter a lot of free floating barriers that
move at random and you would have a killer place to play war games in. Get a
light weight aerodynamic shell, put in a couple of high pressure air tanks,
use them as reaction motors, fix a few ducted fans and some control
surfaces, a targeting laser and you have an adult version of paintball, with
fighter jets. I would pay to play that game, the fans move you most of the
time and the air jets when you really need to scoot. Okay, nobody is going
to pay to build such a thing but we can dream cant we? In fact, I thought
that was what we were supposed to do?

>But if one wants to talk about mega-habitats made from Buckytubes or
>diamondoid, I think there are other more viable designs. Here's one:
>
>http://www.iase.cc/openair.htm
>
>http://www.orionsarm.com/whitepapers/SpaceRings.pdf
>
>Of course I'm known for the position that reflecting natural sunlight
>with mirrors for illumination is better than artificial illumination, so
>I would replace the central light source and its associated optics with
>a mirror arrangement much like that for the Stanford Torus. But with a
>twist which takes us to a situation SF fans might find interesting.
>
>The Stanford Torus has two rings of mirrors which reflect light from the
>primary mirror out to the interior of the torus.
>(http://members.aol.com/sandycombs/torus1.jpg) The rings are about half
>the diameter of the torus, so two rings of mirrors are needed, with the
>mirror segments staggered in such a way that the beams of sunlight
>coming down from them dovetail.
>
>Now in this mega space-ring design, we'll need to have a day/night
>cycle. That could be accomplished by swiveling the mirrors, but there's
>something else we could do which would eliminate the need for moving
>parts. We could have one ring of mirrors instead of two. Now we have
>gaps in the beams of sunlight projecting outward, and 50% coverage. We
>arrange for the ring of mirrors to rotate slightly more slowly than the
>floor of the habitat, so that sunlight and shadow passes by a given
>point in a 24-hour cycle.
>
>This winds up looking very much like Larry Niven's Ringworld, with its
>shadow-squares. Such a structure, while at a much smaller scale than
>what Niven proposed, would scarcely be visually distinguishable from it,
>if standing on its surface. Such a structure might be a good deal more
>realistic, though, since it only requires materials beyond our present
>ability to create, instead of ones totally beyond present scientific
>knowledge.
>
>Regards,
>
>Mike Combs
As usual you have given me things to think about, Ill have a look at the
links you provided and have a think about what you have said. Thank you for
your input.

Darren