A Suggested Program of Space Settlement]

As I see it, when an O'Neill settlement finally comes to fruition, I
don't think it would be something O'Neill would recognize. O'Neill himself said much the same thing; that he'd be surprised if actual space settlements much resembled the present-day artists conceptions. He viewed the designs derived in the 1970's as proof-of-concept efforts, not as the final word on what would be the best designs. I haven't
read O'Neill's work myself, but as I understand it, an O'Neill colony
is envisioned as a giant construction project using more or less
conventional assembly techniques, but vastly scaled up. E.g. the
pictures of giant "wheel"-type space stations being assembled in
orbit by astronauts and a swarm of space shuttle/Venture Star type
spacecraft and/or orbital shipyards found in many of the books
about "our future in space."

Even if launch costs could be dramatically reduced, say, to $100 a
pound or so, I do not see such construction ever being economically
feasible. Passing judgment on concepts not yet studied in depth is always dangerous (I did the same thing on the subject of planetary terraforming). One thing which seems to have escaped your attention is that the proposal never involved lifting construction materials from the Earth to space. It was always assumed that such material would be lifted from either the moon (via mass driver) or from Earth-Approaching asteroids. And while it's true that many artist's conceptions have involved fairly conventional construction methods much as you describe, the reality may be quite different. Vacuum vapor deposition techniques, for example, hold our promise for making large, seamless pressure vessels in a manner much less demanding of labor than what more conventional construction methods might suggest. In terms of delta-V, construction difficulty/danger, etc.,
it would be far easier and cheaper to build a city on Mars. Many consider this point so obvious as to not require much in the way of further discussion. But I think it's unsupported by any detailed comparative engineering studies, and is based on a kind of planetary chauvinism. No giant orbital shipyard or complicated microgravity
construction process necessary. You seem to proceed from the assumption that construction in microgravity is complicated. What if it turns out that gravity is the major complication in assembling large structures, and, properly engineered, 0-G construction is in some ways actually easier? Nor would there be the vast, up-front capital expense and decades of
construction before people could move in and start producing
revenues. Had the British East India Tea Company been required to
build a full-fledged London or Liverpool in America before they could
send in colonists, I doubt they'd be able to raise the many billions
it would take even today. I don't think anybody ever proposed that High Frontier would begin with Island 3. However, Mars has significant advantages over NEO's as a source of
nonperishable resources such as metals and volatiles. Since it has a
useable atmosphere water and an Earthlike mineral composition, and
our millennia of mining and colonizing experience is derived from
planetary conditions, it will be easier to build substantial colonies
and industries (using more-or-less conventional technologies) on Mars
than on NEO's. On the one hand, you project genetically engineered space-going life forms large enough for human habitats, nanotechnology churning out diamondoid, and genetically modified humans adapted to the space environment. Then you later say that Mars has an advantage over asteroids because you're concerned about our ability to successfully adapt our mining and refining methods to space conditions. This strikes me as terribly inconsistent. I would disagree with the contention that settlement, mining, refining, or manufacturing activities on Mars wouldn't have to be very nearly as extensively revamped for the Martian environment as for the orbital environment. Certainly the requirements for creating large, pressurized volumes will be nearly the same. Portions of an orbital structure can rotate to provide 1/3 G anywhere a small amount of gravity is advantageous. True, one cannot cool a steel mill in space by running many thousands of gallons of water from a nearby stream thorough it, but trying to do the same thing on Mars would only be marginally less difficult. On the other hand, industries in space can do tricks which industries on Mars cannot, such as power themselves 24 hours a day using solar energy, and build solar concentrating mirrors several city blocks in area out of aluminum foil and coat hanger wire.

Regards,

Mike Combs