Talk:Blacksmith

On Luna meteoric iron has shown up as tiny bits in the regolith. If on Mars this iron is conveniently available in large chunks requiring minimal processing to use, it has yet to be demonstrated. Such deposits might not be close to a settlement if they exist.--Farred 00:59, 15 February 2010 (UTC)

Many multi-tonne pieces of meteoric iron have been found on Earth, even though its orbit is intersected by far fewer asteroids and the meteorite's geological lifespan before eroded or buried is far shorter on Earth's surface. So it's simple extrapolation to expect even larger pieces to be even more abundant on Mars and, to a lesser extent, on the moon. We've done only a miniscule amount of exploration at the necessary detail, so that doesn't tell us anything. As for location, if there is subsurface ice over one-quarter of the surface of Mars, and 400 kilotonne-sized iron meteorites, that gives us 100 locations to choose from with both ice and iron. Frontiersman 01:39, 15 February 2010 (UTC)

BTW, do you know of any good studies about the propellant costs of surface-to-surface rocket transport on Mars? Frontiersman 01:48, 15 February 2010 (UTC)

Simple extrapolation may be simply wrong. We cannot count on it until it is proven, but it is a reasonable guess. I do not think there are good cost estimates for producing anything on Mars yet.--Farred 02:25, 15 February 2010 (UTC)

Let us pool our ignorance and document how much we know that we do not know about meteorites. First, there are more meteoroids and asteroids that cross Mars' orbit than Earth's orbit. What is the numerical difference? I do not know. Second Earth's larger gravity well draws a larger fraction of the nearby meteoroids to strike it than does Mars' gravity well. What is the numerical difference? I do not know. Third, Earth's atmosphere tends to stress stony meteoroids of less than about a hundred feet or so in diameter and more than some unknown diameter to the extent that they explode in the air and leave no trace but dust on the ground but slows 100 foot diameter iron meteoroids so they have less of a tendency to vaporize on hitting the ground. To what extent does this enrich the number of intact iron meteoroids available to be found on the Earth's surface as compared to a world with a negligible atmosphere? I do not know. Fourth, Mars had water on its surface in the geologically recent past. This water would have had an equilibrium level of dissolved carbon dioxide making a somewhat acid solution. To what extent would this have dissolved iron meteorites and left a red iron oxide residue spread over the planet? I do not know. Fifth, I hear that Mars rovers found little bits of meteoric iron. How does this evidence affect the likelihood of finding industrially useful quantities of meteoric iron on Mars? I do not know.

Are there any more factors that would influence the likelihood of finding meteoric iron on the surface of Mars? How much ignorance can you add to the pool? How much are we ignorant of that neither of us knows that we are ignorant of? If we want to avoid disappointments and criticism that we were wrong in suggesting an unworkable strategy, we must be cautious to avoid basing plans firmly upon things which are only uncertainly known.--Farred 23:06, 15 February 2010 (UTC)

Those are all good questions to ask. They will be answered by more detailed planetary science in the coming decades (although with some research effort many could be answered with the data we have today). Alas, today, almost nothing we need to know about either economically or physically self-sufficient colonies is firm. We face the task of using what we do know, along with our judgments and common sense, to separate the slightly speculative (in which category I put accessible kilotonnes of meteoric iron on Mars) from the speculative (e.g. the possibilities of gold and diamond on Mars, or the possibility of radically lower launch costs, or how large an industrial infrastructure is needed to build electronics) from the wildly speculative (e.g. self-replicating machines). We could use even finer gradations of speculation, a scale. But we might not agree on many of the places to put various hypotheses on that scale.

BTW, your list of questions above plus the text on meteoric iron I have in the article would make a great start for a new article on meteoric iron. Frontiersman 18:35, 17 February 2010 (UTC)