Island A

There would be much more architectural freedom to choose alternative
configurations of the tanks if they did not rotate. For example, seven
tanks could be arranged in hexagonal closest packing arrangement if that
were desired (just an example --- I don't know whether hexagonal closest
packing arrangement would be good or bad, but at least you'd be able to
consider it in a non-rotating design).

Interior space planning would be less constrained if the workshop did not
rotate. The inside of a tank is curved. Only certain orientations of
the tanks will allow efficient use of that space when there is gravity.
If the workshop doesn't rotate, then curved walls aren't that constraining.

Ron Menich

"Bettie
04/20/01
01:38 PM
Please
respond to
ssi_list

There was a back of the envelope design by O'Neill shortly before his
death.
It called for 6-8 Shuttle external tanks to be tethered together and spun
providing necessary volume for a small 100 person colony, workstation
place.
SSI

>
> Rotation seems to me to be a nice-to-have rather than a minimal
requirement
> for an initial orbital workshop.
>
> Ron Menich
>
> hollroa@...
ssi_list@...
Island A
> Please respond to
> ssi_list
>
> Given the enormous start-up costs of the O'neill vision, it seems
unlikely
> that
> Island one will be the first colony to be built. I have been looking at a
> different approach. My idea centres around placing a workshop in L5, that
> is
> specifically designed to construct SPS modules. For lack of a better
name,
> I
> will call this island A. The basic element of the workshop is an iron
> sphere,
> approximately 40 metres in diameter. The sphere rotates twice per minute.
> The
> sphere is divided into cylindrical floors. The floors are divided into
crew
> quarters, manufacturing workshops, ore processing facilities, a
hydroponics
> bay
> and a satellite assembly hall. The satellite assembly hall is a cylinder
> that
> lies along the axis of rotation. At each end of this assembly hall, there
> lies
> an airlock. These are used both during the launch of finished SPS modules
> and
> for the docking of supply ships, ore carrying ships and various other
> spacecraft. The assembly hall is 10 metres in diameter and 40 metres
long.
> Lunar ores are delivered to the facility through its axial airlocks.
> The
> ores are then taken to a small workshop, where they are processed into
> manufacturing materials such as Calcium, Titanium, Iron, Aluminium,
> Magnesium,
> Silicon, Rutile, Ilmenite, e.t.c. These materials are then used in
various
> other
> small workshops for the manufacture SPS parts.
> The assembly hall is far too small to house a full scale SPS
satellite.
> For
> this reason it may be easier to produce the SPS in modules and assemble
> them
> tele-robotically outside of the habitat. If a 20MWe SPS can be
manufactured
> and
> assembled in one week, then a 1000MWe SPS could be built in 1 year. If we
> assume
> a 40 year life time, and a 0.1$/KWhr rate of return, the SPS will be
> produce
> $35billion through out its life time. This amount would certainly exceed
> the
> cost of producing it.
>
> The facility itself could be produced almost entirely from lunar
derived
> iron. Out of all lunar derived metals, iron is the easiest to produce. It
> is a
> by-product of oxygen production. The entire facility could be formed by
> vacuum
> deposition of iron, onto a thin shell of polymer. The Polymer shell would
> need
> to be brought up from Earth, but would only weigh a few hundred kilos.
The
> interior cylindrical floors and assembly hall would be constructed in the
> similar way. The oxygen that is liberated from the iron, will be useful
> when the
> time comes for habitat pressurisation. The entire habitat might weigh in
at
> 200-300 tonnes, minus the furnishings. Most of this mass will be lunar
> materials.
>
> The construction crew could be housed within a converted shuttle
> external
> tank, during construction. This would be fitted out in LEO, and lifted to
> L5
> using low thrust ion engines. The crew housing, would probably resemble a
> Zubrin
> style Mars hab. The external tank could be shipped back to LEO and fitted
> out as
> a ferry, after construction of the workshop is completed. A solar
electric
> propelled ferry, would be extremely useful for shipping people and
> materials
> between low-Earth orbit and L5.
>
> Despite its small size, island A will require a relatively large amount
of