The future of humanity in space lies in junk.
I've been asked before what I think humanity's ultimate future in space will look like. There are many possibilities, and truthfully, there's only so far into the future that one can make an educated guess. For those of you who frequent the main site, Orbital Vector does attempt to categorize many fantastic, far-future technologies. However, trying to "realistically" predict the nature of space travel and colonization beyond Tech Level 15 (technology circa 100 years from now), considered the highest of the 'hard' science fiction levels, is problematic. Tech Levels 16+ begins contemplating technologies based on science that is as yet still highly speculative, and can't really be included in any attempt at 'realistic' predictions. To be perfectly blunt, we don't know for sure if any technologies beyond Tech Level 15 are actually possible in the real world, so for this entry at least they'll be mostly left out.
So what can we get at Tech Level 15? Actually a great number of technologies that can make profound contributions to the way mankind can utilize the environment of space to benefit itself in scientific, economic, and cultural terms. The most important of these include:
--Advanced nuclear fission power and propulsion
--Fusion power and propulsion
--Advanced, long-enduring space habitats
--Advanced computer systems, possibly true AI
--Alternative energy methods
--Widespread industrial production of carbon nanotubes and other advanced materials
--Zero gravity and nanotech manufacturing and fabrication
--Increased human longevity and advanced bioengineering
--Redirection and engineering of small celestial bodies
I think over the next century and beyond, humanity will continue its slow but steady expansion into space. I'm sorry, space fans, but the Apollo era seems to have been the exception, not the rule, to how the world community handles space. Big, frenzied pushes like it, if they ever come again, will likely be rare and short-lived. Rather, if you look at the past four decades since, you can see one by one more nations across the globe setting up their own space programs, more industries becoming involved as more profits from it are realized, and a much greater percentage of the population now believes at least part of our race's ultimate destiny lies beyond the constraints of Mother Earth.
We need to disavow ourselves of a notion that space is a race we need to hurry up and win. Rather, very practically, it is an expansion of our species into a brand new ecological niche, one far, far vaster than any we have encountered before. This is going to be the work of a great many generations, and what we're doing today is just one rung on a very long ladder.
THE most important technologies, despite what some may attest, are not so much those of space propulsion, but rather space habitats. Propulsion is an important field, but even if our wildest dreams about plasma and fusion rockets are realized, people are still going to have to spend long periods in space to get anywhere--months or years or even longer. Future space pioneers are going to need habitats that can readily protect them against vacuum, radiation, and impacts, as well as provide air, water, food, and other essentials for life.
This is where the 'junk' comes in. Asteroids and comets, the junk debris left over from formation of the sun and planets, exist by the billions around the solar system. They present a vast treasure trove of resources. And unlike the larger planets and moons, they can be made mobile.
Despite the ideal envisioned in many scifi sources, I think it actually would be more efficient to build centralized processing nodes (say at certain trojan points throughout the solar system, starting with the Earth-Moon Lagrange points) and move the asteroids to them, rather than send out mining ships hopping from asteroid to asteroid. This wouldn't be a quick process--moving any one asteroid would likely take a number of years--but things could be coordinated for the rocks to reach the processing node or a holding point in a steady stream over the decades.
Each processing node would be able to hold much heavier-duty equipment, more automatons, and more workers than ships sent out into the asteroid wilderness on their own. They would in turn make the mining and processing the space rocks that much faster and efficient.
But there is a point of diminishing returns, economically. After all the profitable materials are removed, what does one do with all the left over husks?
If they're the right shape (or can be molded into one,) size, and composition, you can turn them into the raw shells of space habitats. A number of other sources speculate how one could hollow or modify an asteroid or comet to accommodate a human colony, so we can gloss over that here and assume its doable.
Would there be customers for these shells? I think a great many. Most of this century will concentrate on man-made space stations. However, many will find these to be both expensive and self-limiting, as one still has to fabricate every single component and launch them. With an asteroid, much of the initial digging can be done at the processing node according to a buyer's needs, and the buyer could concentrate more on interiorneeds without having to worry over much about the outer shell. Any such colony would start small, say in one small area of the space rock with a few dozen individuals, and would continue to slowly expand over time as automatons and humans continue to dig and rework the floating mountain. Within a few decades, maybe less, one could have a large O'Neill-style colony that could hold many thousands.
At first, rich nations and more prestigious groups would invest in these new colonies, but over time, prices would lower so that smaller groups and individuals--especially individual families--could buy stakes in them, giving birth to a whole new era of homesteading on the high frontier.
Many of the asteroid colonies would be moved into or near Earth's orbit, in order to facilitate trade and travel between the mother world, the Moon, and all the other colonies as well.
And over centuries, more and more of these colonies would be established. They could end up numbering dozens, hundreds, or even thousands.
And even while asteroid colonies start up, similar exploration, exploitation, and eventual an manned presence would be established on the Moon, Mars, Ceres, and eventually Mercury, the moons of the gas giants, and perhaps even a modified Venus.
So this is how I envision the solar system about three hundred or so years from now, with hundreds of asteroid colonies at the Earth-Moon Lagrange points, at the Earth-Sun Lagrange points, and in their own independent solar orbits nearby. Smaller clusters would be found in orbit about Mars and its Lagrange points, and in the Asteroid Belt. Independent asteroid colonies would dot the solar system here and there, owned by more isolationist interests, with comet colonies eventually dominating the outer system. And a number of these colonies, along with clusters of raw comet bodies to provide consumables, would be flung even farther out, into the Kuiper Belt and the Oort Cloud and beyond, to function as resupply bases or launching points for possible interstellar-bound probes, exploration vessels, and generations ships.
Some people have lamented that the Space Opera future so beloved of scifi fans will likely never come to pass; the universe simply isn't set up that way. In a way, they're right. FTL travel is in all probability impossible, and life-bearing worlds may be incredibly rare among the stars, even more so any with living civilizations similar to our own in development.
But the dream of hopping in a spaceship and visiting one of hundreds or thousands of strange exotic worlds is certainly a possibility. The diference is, instead of going out into the universe and discovring it, we'll build it right here in our home star system. The planets, the moons, the asteroid and comet colonies, will likely be founded by many diverse groups, who will themselves evolve culturally on their own as time goes by. Throw in advanced bioengineering and a willingness to vary the human form for various purposes, the Solar System may indeed by an exciting and amazing place to explore a few centuries hence.
A thousand exotic worlds built on the dreams of ourselves and our descendants lies in our possible future. Its just a matter of how much we want it.