President's Commission on Moon, Mars and Beyond

>Totally agree. The only way to go seriously for manned exploration as far as
>I'm concerned is (robotic) colonization of the moon first, then set up a
>manned base there,

I totally agree with you on the robotic part also. First begin with
robots and automated processes.

Though I would like to add another thought and prefer just to
concentrate on the advantages of it since I think you will find
disadvantages very fast :-) .

How about building the hull of a space ship out of concrete and
completely in space derived from asteroidal resources using molds to
concrete it near the material source and bring the ready made hull
back to earth orbit or into an earth-mars cycler orbit?

The construction crew would first get into the ready made hull when it
returned finished outside into earths magnetic shield.

The advantage would be that we could handle masses with huge earth
weight which is also huge on the moon but have practically no weight
in space with very weak propulsion devices (ion drives for instance).
And we dont have to launch this tremendous weight from the moon
again because its already there.

What has to be launched from earth are relatively lightweight molds
and lightweight space crafts because they only use fuel effective
electric propulsion instead of chemical propulsion or atomic reactors.

I figure that we could pick up most of the materials needed for
concrete from stony asteroidal surfaces, not having to dig down.

So asteroid prospecting devices (in fact little space crafts like
flying container with arms or flying scoops with hatches) would
deliver the materials (sands, water, cement) to refining and
processing units in space from were the different materials get to the
space based rotating cement/concrete mixer units.

The mixer units then would deliver the concrete to the molds which are
used to form rings which then are put together to the outer hull of
the concrete space ship, or space station or space habitat.

Those rings would be set together with belts and braces and concreted
from the outside on the seams.

>then build big fat 500 tons ships using local materials
>and go off wasting time investigating why Mars is the dead piece of space
>waste it is... :)

How did you come on 500 tons? Is this just a guess or did you made
some numbers? What would the ship look like?

I figured about 214 thousand tons for a 108 meters diameter pretty
flat cylindrical hull of only 18 meters length and 4 meters wall
thickness (like a checkers draughts man - if my translating program
serves me right) and 2.4 tons/m^3 earth weight of the concrete
material.

I choose this form because it is simple to put together in single
rings and we dont have to account for aerodynamics because it would
be solely space based.

Dont let you irritate of the huge masses involved.
Humanity had handled that already with the pyramids or with sky
scrapers and it didnt had the advantage of letting most or all of
gravity out to handle materials.

Now we could let lift those rings (the bigger ones weighting about
3100 tons on earth) through robotic space crafts without gravity at
all.

>Ho, and once you have removed the annoying lift-offs from Earth you could
>use nuclear propulsion at will, and then you may as well need something like
>liquid-filled inertia-dumpers cells of some kind as the only thing that
>would stop you to go to Mars in a week is the acceleration that the crew
>could stand! But you could take it easy and accelerate (or decelerate) just
>fast enough to keep at a good old 1 g, and forget about the effects of
>zero-g... as a matter of fact you could push it a bit, say 1.2g and get the
>crew back more fit than when they left...

If atomic propulsion could provide 1 g, than my design could come down
immensely in dimensions and mass since I thought of an rotating
cycler to deliver gravity.

>Dreaming? Could be done within a decade or two if we stopped spending money
>fighting for supremacy and start put it in it now, but then THAT's
>dreaming... :)

I do feel the same.

>Dream for dream, I'm still a lot more interested in a robot digging dirt on
>the moon by the ton than a man (healthy or otherwise) drilling an inch hole
>in a rock on Mars... :P

Would be the same for me,
- if we could change the moon against near earth asteroids here :-) .

Frank