I’ve just been left at the altar too many times. I’m still waiting for my flying car.

I’ve spent my entire adult life working on getting humanity into space in a big way.

I know it’s not beyond physics. I also know it’s not beyond technology, even current technology. We had nuclear rocket engines in the final stages of development forty years ago.

Profit? I guess we’ll see. The private sector has a pretty good record of making money off of things.

Mostly now I’m sitting back and watching other entrepreneurs try to do what my startups couldn’t. Maybe our group was ahead of our time, or more likely, maybe the dice just didn’t roll the right way. But if someone else does it, it’ll be just as good for the human race as if I did it. I’m cheering them on.

I am very much a booster and supporter of space exploration. But realistically, living and working there in a manner that pays for itself and even generates a surplus for further investment, is beyond our current engineering, and may even be beyond our current physics.

I did a lot of work on this concept years ago, too. It’s actually workable if you can get transportation costs low enough.

It’s safe, too. The beam designs were very low power, spread across wide areas, and controlled by fail-safe aiming systems (active focus). The receiving antenna was basically a metallic net covering many acres, supported high in the air on tall poles.

Light would pass through the net, and you could even grow crops underneath. The space beneath it would be as safe as the space outside the door of your microwave.

Birds flying through the low-power beam might get warm, but would have no permanent effects.

Some designs built the nets offshore on pylons.

A lot of people have worked on the technology of moving asteroids, refining on site, transportation, energy needs, propulsion techniques, and cost/benefit.

Obviously, we have a ways to go before asteroid mining is a major source of resources, but we already know where a lot of the nickel-iron asteroids are.

Here’s one.

Forty years ago nobody would have thought that it would be cost-effective to haul oil up from under a mile of ocean, either.

Assuming this technology were already developed (which is where I suspect the real costs will probably arise), just the amount of energy needed to move a ship full of miners, supplies and machinery out to the Belt and keeping it supplied is probably substantial.

And it should be kept in mind, as in all resource activities, the exploration (prospecting) costs will probably outstrip the extraction (mining) and transport costs many times over. You have to find it first before you mine it.
As Walter Huston reminds the boys in “Treasure of the Sierra Madre”, gold is valuable not just because you have to pay men to go get it; someone has to grubstake all the men that went out and came back empty-handed.

No, I haven’t calculated it either, but I suspect the price of belt riches will never make it worth our while to go there and bring it here, even if it is neatly stacked there in ingots (or even finished industrial products) ready to haul back.

Of course, one can hope that advances in propulsion technology, and developing markets in space itself for this material may change the economics considerably, but it will always be a chicken and egg problem. How do you build space stations in the asteroids without asteroid mining, and how do you provide investment for your asteroid mines without space stations out there who will be markets for the product?

And it certainly can’t be done if everything we need to get started has to be lifted out of earth’s gravity well first. You need a functioning space infrastructure already in place to build on.

The major obstacle is the cost per joule to accelerate your vehicles and their cargo to and from their shipyards, their mines and then their markets. Advanced technology may drastically reduce the dollar cost/deltav-kilo, but the energy cost in Joules is fixed by physics.
There simply is no way around it. Everything you need will have to be accelerated there, and every gram of product will have to be accelerated back–even if the costs of finding and extracting it are zero.

Of course, we have no idea what technological advantages we may have available to us in the future.
But it might be interesting, as an exercise, to calculate costs and break-even points for a similar problem where aircraft (not steamships) are used to support a mining activity in Antarctica. We make the assumption (and its a stretch!) that someday spacecraft and space colonies and factories will be as cheap to operate as aircraft and Antarctic bases factories and mines are to operate today. At what point will the cost per kilo of the stuff we bring back break even?

We did it (with steamships and whales) a century ago, so we know the problem is solvable in principle. The question is, can we make money at it now?

Sigh…to be twenty again.

The prices are obsolete (I may update this someday), but the analysis is basically correct.