Using Concrete to build space ships...

>>Our sun is out of hydrogen and ejects it all the time with the solar
>>wind. So you may find the main part of water not only in ice-form but
>>in all minor planets which get touched of the solar winds.
>
>I am an avid subscriber to the KISS formula... As such, throwing in a lot of
>additional steps to obtain building materials seems to open up many more
>opportunities for Murphy to creep in, not to mention additional expenses. In
>short, why use water if you don't have to?

That would be the same for me also.
On the other hand it would be more of a step by step approach I am
thinking here.

Going to asteroids to see if we are able to extract materials there
would be one step we had to do anyway and is important in its own
and that should be the first step.

It would be rather cheap reachable with inexpensive missions using
very lightweight space crafts like the ion thruster driven Japanese
Space probe Muses C which is out to get asteroid samples now.

The possibility to get resources without having to struggle with a
steep gravity well shows so much potential that we should do that step
first.

If it fails out of whatever reasons my assumptions are baseless but if
they are not baseless we could win a lot in the sense of cost savings
potential and therefore should try this step first.

The second step would be to develop better extracting and processing
techniques for those materials and the third step would be to get the
transport infra structure running.

So the flaw of my thinking is that I am several logical steps ahead
here, each with the possibility to fail - but I cant help it,
sometimes I like to do that :-) .

Frank