New here, asteroids prefered

Victor,

Ultimately a space based civilization would use whatever is most effective for the situation.
No one doubts that asteroidscould be a resource treasure trove. Reading this group for a few years, I suspect people may have a short term difference of opinion, but the majority see the long term goal as humanity on habitats that are not located on a planet or the moon. That said, we have biases on what goals we should focus on:it could be a short term one (the moon is the most economical place to start our foray into extraterrestial resource extractions) to someone's long term view (Mars is the next home for humanity).

With that in mind, let's focus on thedifference over what some peole view asthe bestshort term step for us in space. Just like there is a split between robotics / telerobotics vs. human presence driving construction / processing, there is a preference for moon vs. asteroids.Let's covera couple of your points:

1."it's commercial profits and potential profits that will, in the final analysis, get us and keep us off the planet. Some of the fields of study yielding, or about to yield, results with a high probability of commercial applications that require an environment of microgravity"
Yes. Also, space solar power for earth (which technically is not always a gravity vs. zero-g issue)

2. "Use the Earth crossing asteroids as travelling habitat/spacecraft to transport men, materials and ships to the vicinity of Mars, Deimos, Phobos and the Belt and back. All of that can be accomplished in 30-40 years if we make it a priority"

That timetable seem very optimistic. Based on the national priorities on earth and budgets, the only way we'd get funding for this, would be after great advancements in robotics or launch costs. Does anyone see a great breakthrough in launch costs the next decade? Most likely, the pilot programs wouldbe out there now. Therefore,that agreesivetimetable would depend on getting minimal mass out of this gravity well and not worrying about how a crew returns. (focus on robotics)

As for using the asteroids for construction in earth orbit... More and morenationshave avested interests in the orbital environment. Looks like we are in for a multi-year debate on the legality and liability for asteroid capture. My opinion: we've got years before there will be an agreement allowing any government or business to capture asteroids and place them around out planet. (Al Globus wrote about asterants that carry small captured weightsthat might be acceptable.)

"I don't see there being sufficient materials to effect any kind of 'economy' on the moon- what do you have to sell, or what potential can you offer to prospective manufacturers to set up shop there?"
Yes,there are a asteroids can harbor alarge cadre of elements.

For purely practical reasons, I suspect nearterm space base resource utilization will come from the moon. Why? It is close. Telerobotics are an option (2 second delay).Shielding andstructure are the greatest contribution toa habs mass, minimizing earth launch to components that are difficult to fabricate ormaterials unavailable from the moon. This couldgreatly reduce construction costs for our nextsteps - including those withasteroids.

Amajorbenefit is potentially shorterinnovation / engineering cycles with the moon. Many have said asteroids inLEO haveeven shorter cycles, but I think in the years it will take to get significant asteroidal mass in orbit, we could have been telerobotically mining on themoon for a few decades.

Without asteroid capture, the launch / equipment engineering cycles are not better than the moon. And without asteroid capture, we need lots of advancements before we can launch an expedition and get the benefits of resource extraction.

"there's the factor of getting those products to their markets: 1/6 g... will still require significant use of fuel (or a significant outlay for a linear accelerator, skyhook, etc.)- much more of an expense than would be incurred by shipping from a zero g habitat."

Right on both points. The moon is for primary material processing,building mass,and solar power. Gettingobjects off the moon and delivered to a useful place is a challenge, but probablysafer than capturing asteroids.

On the other hand, how do we get to build the "zero g habitat" with its lower material shipping costs?

If the answer is asteroids, then who is accepting liability for herding them into orbit?The cost of a space program (if privately funded) would be bankrupted with one bad incident. Therefore, I don't such any large scale effect for many decades. Maybe not ever. Once technology is advanced enough no really large asteroid would be brought closer than a very large orbital patharound Earth. Very small asteroids 1-2 meter, maybe.

"Where do you get your building materials for your settlements (unless you utilize tunnels beneath the surface sealed somehow, or Bigelow style blowup modules or domes)?"
Someone else could go into those details. I favor robotics for the moon. In the near term it is the safer and more economical approach. Structures to be built initially would be those shelters needed for certain equipment or processes. Trying to build a large strucuture or lunar town (anything more than a construction shack for 3-4 people) would, in the near term, be a big distraction of resources from building orbital space based habs.