L5 satellite workshops.

>
> The production of Aluminium is quite a power hungry process. It
also requires
> carbon electrodes. As you stated earlier, carbon is rare in lunar
material. On
> Earth, about 20KWhrs of electric power are required to produce 1Kg
of Aluminium.
> In addition to which, you don't have to recycle the carbon on
Earth, and high
> quality Bauxite ore is available. My guess is that Aluminium will
be saved for
> applications where its high electrical conductivity put a premium
on its use.
> Iron, on the other hand, is likely to be an abundant by-product of
oxygen
> production processes.

The power is considered no problem in space with solar power
available. Does the electrolysis use much carbon??

If we could use iron and iron is much cheaper/easier to extract and
more plentiful then yes I would agree it would be preferable to use
it.

It is the soda-lime sintering process that is considered in the NASA
AMES study - does this use electrolysis??

I think Aluminium was considered preferable for several reasons, it's
lightness especially.

>
> The idea of rotating the shielding along with the workshop, is an
interesting
> one. When one considers that pressurising a pressure vessel to
standard
> atmospheric pressure, is equivalent to 10 tonnes of Force/square
metre, rotation
> a shield at 1g with 2.5 tonnes/m2 of shielding on it, would not be
a fundamental
> problem. So I would guess that even slightly impure iron, could be
used to
> construct loaded members, within the rotating shield. But, we may
want to
> consider keeping the revs down. NASA studies suggested that high
rates of
> rotation caused dizziness & nausea. Rotating the hab to 1/6th or
1/3rd g's may
> be easier from a construction point of view as well. Rotating the
shielding,
> would also allow us the freedom of direct wiring between the inner
hab
> workshops, and the outer surface of the shielding. This makes the
installation
> of solar panels on the outer surface of the shield, relatively
easy. A dozen or
> so panels, 10 by 50 metres each, placed along the circumference of
the sphere,
> would be able to produce 1 MWe of continuous power. These high
power levels
> would be essential for magma electrolysis, machining of parts, re-
cycling of
> scarce materials, the production of Aluminium and Titanium and high
data
> transmission rates during communications with Earth. It may turn
out that is
> large amounts of aluminium are required, 1Mwe of continuous power
won't be
> enough.

I was suggesting this type of shielding for habitats. The dumbell
configuration involves joining two spheres via a supporting member.
This gives you a larger radius of rotation and therefore a lower
rotation rate to give one-G (2 revs per minute is considered the max
rotation rate bearable which means a radius of rotation of 230m).

I would suggest the workshop is kept weightless - especially for the
construction of large structures such as SPSs. Of course a small
amount of gravity might be desirable for some construction techniques.

As for the rotation of the shield - I was suggesting this for the
rotating dumbell habitat. The reason for this is if you can imagine a
dumbell rotating - the shape of a stationary shield has got to at
least a toroid within which the dumbell can rotate. If we attach the
shield to the two spheres this drastically reduces it's size (it only
has to cover the area of the two spheres) and even thogh the two
spheres and the joining member will need to be stronger there should
still be a considerable weight saving.