Re: Space travel is no longer SF

On Sat, 06 Oct 2007 15:58:49 -0700, Quadibloc <jsavard@xxxxxxxxx> wrote:
Jasper Janssen wrote:
On Wed, 03 Oct 2007 18:10:22 -0700, JSBassior2007@xxxxxxxxx wrote:

Ah yes, "useless milling machines and digital fabbers." How _could_
one _ever_ use those as part of the production process for building
habs and greenhouses? I mean, they've all been programmed to only
turn out left-handed screws and dildoes, right?

Do you even know what the current state of the art of fabbers is? They're
limited, *inherently*, to working with a single material with a single set
of properties. They can't build something like a box inside a box held up
by arms sideways -- only do it, and then with difficulty, as long as each
layer is supported from below. That's fine for small structures (just
rotate them appropriately), but it falls down miserably for larger, more
complex ones.

Milling machines, and drill presses, and the sort of thing *I'm*

Yeah, my beef is particularly with his insistence on fabbers. They're
great for prototyping stuff, making sure a new device lies well within the
hand, etc, and you can use them forensically for things like copying a
skull (with some digital processing if needed in between the scan and the
print) for facial reconstruction, alla that.. but they simply don't do
making machinery. Not even the sinterballs-plus-brass-infusion type is
anything like strong enough. And brass is fairly rare on Mars, come to
think of it, isn't it?

It will take some time before the colony on Mars grows to such a size
that it will need assembly lines - by then, it should be able to craft
them itself.

Assembly lines are more an organisational tool than an actual device,
anyway.

No digital fabricators - perhaps numerically controlled milling
machines - but machine tools and equipment to extract metals from
ores.

CNC-controlling milling machines and lathes isn't really all that hard --
it's especially unhard computationally speaking, you could do it
effectively with 1975 tech, after all. Even the physical interfaces --
stepper motors and amplifiers for same, essentially -- aren't all that
hard, and if you make them physically large I suspect that you could have
local facilities for re-winding them not *that* far into a project that
involves setting up a smelting plant anyway.

If you get to large enough machinery to build & machine, which also
requires large tools, hand-cranking the tools might be unfeasible anyway,
and even for small ones the actual drive motor pretty much needs to be
power-driven. Given *that* lower limit on techlevel, I'm not sure it makes
sense *not* to CNC control them, given that computing is one of those
things where progress is still going and by the time it's needed there
will probably only need to be a fairly small mass and energy budget to
provide the colonists with ubiquitous computing for quite a while. I don't
think it's realistic for even a selfsufficient small mars colony to
produce their own computing, though, one could posit metals out, computing
in, on the basis of trade. That works better for asteroids, though.


Jasper
.

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