mistermack wrote:I'm guessing here, but I think that Iron would be last on the list of early space materials.
Iron needs very heavy machinery to work it. And needs to be very hot.
In space that means you would need huge amounts of Iron, to start working iron.
And a hell of a lot of insulation, to keep the heat in at minus 270 deg.
Aluminium would be better I think. But what the moon is like for mining metals, I don't have a clue.
I don't think there is much of an energy cost for taking off from the moon though.
You only have to compare what fuel the apollo astronauts needed to get off the Earth, to what they needed to get off the Moon. There is simply no comparison.
I think the curve of energy-needed vs gravity-strength must be an ever increasing exponetial one, for there to be such a difference.
The escape velocity of the Earth is 11.2 km/sec
The escape velocity of the Moon is 2.4 km/sec
But the Earth figure ignores the drag of the air. So the difference is even greater.
And most of the fuel is needed to lift and accelerate the fuel's own weight.
So the lower the gravity, the lower is that factor.
You could probably fire raw materials off the moon, with a gun, towards an orbiting space station, for very little energy cost, as you wouldn't be lifting the fuel.
I consider this to be simply an interesting speculation - how could we engineer our way around all the "impossibilities". It isn't like I'm ever likely to get up in the morning and kick off an interplanetary mining and transport company!
But anyway:
http://en.wikipedia.org/wiki/Allende_meteorite includes aluminium.
http://en.wikipedia.org/wiki/Allende_meteorite
The size of the machines is surely dependent on the quantity of iron to be worked, isn't it?
We wouldn't necessarily mine the moon. We could divert small meteroids to the moon, and extract directly from those. This would remove the need to mine.
Of course - the question then arises about the number of meteoroids within reach, and within that group, how many have the materials we'd need. (How many would be like the Allende meteorite?
Fuel could be sourced also from meteoroids, as a fair proportion of them contain water. (Which could be split using electricity from solar panels, to create hydrogen and oxygen).
The escape velocity from the moon, and the fact that it is significantly easier to launch from there is the reason I've included it in the first place.
