First let me be clear. I am talking here about my old friend the Plausible Midfuture. I'm not going to answer for AD 40,000, let alone 40 million. And this is obviously not about Romance, for which the rule of cool is sufficient, even if it dresses in Plausible Midfuture outfits as a rhetorical flourish.
But really, guys 'n' gals, we are not going to be colonizing space any time soon. (Well, probably not.) Not in this century, not in the next, perhaps not in this millennium. The whole idea is rocketpunk in the sense of Late Steampunk, the imagined projection of a brief era into a vast and timeless tapestry, i.e. Romance, which is different from real life. That being the point after all.
But in merely practical terms, the Solar System is a whole lot of Oakland, still no there there. Think about the debate over whether it is better to colonize planets (moons, asteroids, etc.) or to build space habitats, so people can actually live in the middle of nowhere. This is no way to sell real estate.
And let's be honest. If it weren't so cool, none of us would be talking about extracting exotic minerals from uninhabitable hyper-deserts, lacking even breathable air, located millions of kilometers away. People in the relevant industries are not talking about it. They are talking about, and investing in, technologies such as nanomaterials that either use less of those exotic materials or permit use of cheaper stuff instead.
He3 from Uranus is an impressive line haul, but a tenfold reduction in the cost of solar cells makes plain old earthbound, tree huggy solar power cheap and abundant. (Under cautious assumptions, roughly 1 TW of peak production per 10,000 square km of collector surface.) Space-based alternatives postulate at least a tenfold reduction in launch costs, and still need relatively cheap cells to be competitive. Deep space alternatives pretty much require a hundredfold reduction in launch costs.
That is a lot to ask of a mature technology, and basic space technology is fairly mature - we have been building and launching space missions on a routine basis for decades.
A launch cost reduction of 100 x (to about $100,000/ton, or $100/kg) might in fact just be doable. Our current launch systems are geared to a low traffic rate, at most a few hundred tons put into orbit each year. A traffic revolution allowing economies of scale might cut costs tenfold, and decades of subsequent streamlining based on operational experience cut another factor of ten.
But even that does not really provide a reason to do it, other than that it would be really, really cool.
On the other hand, there is a place in human affairs (and the economy), for really, really cool: just ask Hollywood. And it is basically sheer coolness that accounts for the ISS and interplanetary missions, vicarious space tourism for everyone courtesy of NASA, the ESA, and a handful of counterparts around the world.
If you are libertarian you can be philosophically grumpy about this, but it has gotten us this far, and there's no sign that private money-making ventures could have done anything like as well.
The one thing in space (besides coolness) that we know is of value is knowledge - itself a form of coolness, among other things. And it will probably keep us going, even if it points at a future of research stations rather than mining colonies.
Support of these research stations may in time give reason to mine stuff in space for use in space, but even if commercial mining firms develop they will surely be largely automated, and incidental rather than central to the long term enterprise of space.
Beyond the midfuture this might point to a Solar System where some research stations evolve into towns, then cities, but situated at points of research interest rather than mother lodes of McGuffinite.
And there is nothing wrong with that, even for purposes of Romance.
Related Posts: Recently on space as the Wild West, and my first post on this general theme early last year.
The image comes, as so often, from the ever-useful pages of Atomic Rockets. And here is another one implying that perhaps it isn't about real estate at all.