Re: Centrifuge on the moon and mars

On May 10, 3:27 pm, Alex Terrell <alexterr...@xxxxxxxxx> wrote:
On 10 May, 15:52, Willie.Moo...@xxxxxxxxx wrote:





Space colonies have been seriously proposed as far back as the 1970s
by engineers and scientists like Gerard ONeill

http://en.wikipedia.org/wiki/Gerard_K._O'Neill

who built large vacuum chambers for particle accelerators. And in
fiction as far back as the 1920s - by John Bernal

http://en.wikipedia.org/wiki/J._D._Bernal

Nearly all these space colonies rotate on their axes to produce a form
of artificial gravity through centrifuge action

http://en.wikipedia.org/wiki/Centrifuge

And this has been proposed in space to produce artificial gravity for
interplanetary trips. Either by tethering spacecraft together and
causing them to spin around their common center

http://en.wikipedia.org/wiki/Gemini_11

Or by building a small rotating cabin within the vehicle, as depicted
in some science fiction movies

http://upload.wikimedia.org/wikipedia/en/2/22/2001-centerfuge.jpg

Well, what about the use of a centrifuge on the surface of a low-
gravity planet to produce 'earth normal' gravity?

At 1/6th gee, adding another 5/6th gee with a centrifuge is possible.
Or on mars bringing 1/3 gee up to a full gee with a centtrifuge is
possible as well.

So, why not do it? Why confine cnetrifuge to zero gee use only?

Imagine a transparent spherical pressure vessel 250 m in diameter on
the surface of the moon. The sphere sunk into the ground 50 m. At
ground level there is ring 200 m in diameter. This is a maglev type
system, that supports a cylindrical wall 150 m tall, and attaches to
another 200 m diameter ring in the sphere above. The cylindrical wall
is made to rotate at 110 kph. Anyone standing on the interior of the
rotating cylinder will feel 1 gee of force pointing 9 degrees from
vertical. It will feel to them as if they're on a gently sloping
surface. Constructing floors and buildings at this slight angle - in
steps - would create a 1 gee environment.

At the base of the moving wall there is lip set at 9 degrees from
vertical. Inside this lip is a set of concentric cone segments
forming concentring set of rings - also supported and driven by
magnetic forces - that move slightly slower then the wall and each
ring moves slightly slower than the ring before it. These are about 1
meter wide and change their angle relative to vertical so that at the
speed they're operating a person standing on the ring feels gravity
pulling them normal to the surface of the ring. A person standing on
the floor of the dome can easily walk across these moving slidewalks
increasing their speed from zero to 110 kph, and into the one gee
field.

In the design I have prepared there is a conical vaned structure
forming a ceiling over the rotating cylinder, that rotates along with
it. This structure allows light into the interior whild managing air
flow and noise. In this way those moving on the centrifuge surface
feel only a gentle continuous breeze not a gale force wind! The
center of the dome is depressed below the 'access ring' and a low
gravity fountain is the central feature of the dome's low gee
interior. This keeps the air moistened and clean and controls odors.

The fountain shoots up to the top of the dome over 220 m above the
fountain level and hits the vanes. These act like fans and disperse
the water into five well defined 'water falls' on the 'upper' end of
the cnetrifuge. The water noise provides a pleasant backdrop to the
operation of the rest of the machinery. The 100 m water falls hit the
centrifuge forming a 'ring river' on the upper section. This ring
river is suitable for swimming. The river drains into five separate
channels along the length of the cylinder interior. The channels
drain out of the 'bottom' falling below the lower lip, and are ejeted
out to a catchment around the outside of the base.

Access to the dome is through a ramp riunning underneath the cylinder
at the fountain level - through an airlock to the outside, or to
another pressurized space. Water in the catchment is returned to the
fountain by five return channels - along the sides of the access ramps
underneat -

The 200 m low gee section surrounding the fountain (3.1 hectares) is
built up commercially.

The 150 m by 628 m area (9.43 hectares) is mostly residential with
some commercial space.

Up to this sort of scale it seems possible, though it might still be
too small to provide 1g without nausea. 2rpm is above the current
"safe design" limit for nausea, though of course we don't know till we
do some useful experiments (likewise the need for this - maybe humans
can breed in 0.38g).

Given that, the design seems more complex than a freefall colony and
is only possible because you build in a 9 degree "non-rising slope".
This would be a curious feature.

On Mars, given the presence of Phobos and Deimos, I'd say why bother -
why not just build a cylinder around Deimos and if you get pregnant of
out of shape (I admit the former is unlikely) you just go and spend a
year in cylinder (or torus).

IIRC Larry Niven called this confinement.- Hide quoted text -

- Show quoted text -

I don't buy that its difficult or costly or especially tricky. I
tried to find an old picture from the 1950s showing a drum that you
paid a nickel and got into and then when it spun up the floor dropped
out of it. This was pre-litigatoin days for America! haha.. So, we
didn't have fancy couches like in the ride below;

http://www.fundacion.telefonica.com/at/ingravidos/imagenes/92.jpg

But you basically had a motor and a drum and walked in on a floor that
was attached to a hydraulic cylinder. The whole shebang was on the
end of a hydraulic arm that swung you up through 90 degrees while you
were spinning. God help you if the spinning stopped in that
atitutde! haha.. or if the wheel broke loose! lol. Probably
explains why its no longer in service. lol. I recall as a kid filing
into the thing see photos probably taken in the 30s or 40s - of people
sitting at a table and chair having tee - sitting as pretty as you
please on the wall! lol.

Some people got sick, most didn't get nauseous as all.

I guess not having practical experience with rides like this makes it
seem special dangerrous or difficult.

It seems to me with modern maglev technology and computer controls, a
200 m diameter system that moves around at a stately 2 rpm - would be
easily adapted to. and no more difficult to build than a skyscraper
today. Probably less expensive since you don't have to pump air and
such through each of the rooms.

And while the steps to level out the gee forces may sound weird when
talked about here in practice the slope is far less than that found in
most San Francisco street scapes - and they use the same technique;

http://leblog.exuberance.com/images/VW-DeHaroStreet-SanFrancisco.jpg

And here little cable cars will take you half-way to the stars! lol.

Also in San Francisco 9 hectares is quite a sizeable piece of real
estate! Since 9 hectares enclosed by a pressure vessel, and sits on
top of 3 hectares while little to obscure it - the economics would be
quite favorable when compared to a domed region without a rotating 1
gee surface.

So, I would argue the economics favor this sort of development - and
the costs are about the same as building a multi-story structure
within the dome - while the openess of the design permits a city scape
like feel.

Again very similar to San Francisco

http://www.indospectrum.com/digimages/sf/cd019_coit_tower_from_lombard_base2.jpg

This following program is dedicated to the city and people of San
Francisco, who may not know it but they are beautiful and so is their
city this is a very personal song, so if the viewer cannot understand
it particularly those of you who are European residents save up all
your bread and fly trans love airways to San Francisco U.S.A., then
maybe you'll understand the song, it will be worth it, if not for the
sake of this song but for the sake of your own peace of mind.
Strobe lights beam create dreams
walls move minds to do
on a warm San Francisco night
old child young child feel alright
on a warm San Francisco night
angels sing leather wings
jeans of blue Harley Davisons too
on a warm San Francisco night
old angels young angels feel alright
on a warm San Francisco night.

I wasn't born there perhaps I'll die there
there's no place left to go, San Francisco.

Cop's face is filled with hate
heavens above he's on a street called love
when will they even learn
old cop young cop feel alright
on a warm San Francisco night
the children are cool
they don't raise fools
it's an american dream
includes indians too

.