I'm new to this forum, so hello to everyone here. I've registered specifically to start this thread, which results from a series of discussions I've had on another message board concerning the future of mankind and manned space travel. Though this subject has almost certainly been addressed before on this board, I haven't been able to find those discussions to the desired depth despite modest efforts at searching for them. My purpose is mostly to bounce my ideas off of the well-regarded membership of BAUT and get feedback.
The argument I made on the other message board was that mankind will almost certainly not colonize space or otherwise live beyond earth's surface to a significant degree in the future. My reasoning is based on the fact that even temporary human space travel, let alone semi-permanent or permanent habitation, is and will always be such an enormously expensive, complex and time-consuming endeavor that it will only be undertaken to achieve a concrete, near-term goal directly benefitting an existing entity. Space colonization is not going to happen "just because." It's not going to happen because a handful of space nerds want it to. And I contend that there is no plausible concrete, near-term goal directly benefitting an existing entity that requires human space colonization.
One oft-touted basis for space colonization is for economic gain. I will show that there is nothing in space that we need that necessitates people living in space in order to get it. Given how unbelievably expensive it is to keep humans alive in space, profit-driven enterprises will not employ them there unless absolutely necessary.
Now, the potentially profitable areas of space are:
1. Satellites. Already here. However, it will never be cheaper to build them with extraterrestrial resources (after factoring in the costs of developing that infrastructure) than to simply launch them from earth. Thus, no humans in space required.
2. Tourism. On its way, sort of. Currently no really concrete plans exist to keep humans in space for more than a few minutes, but, with sufficient reductions in launch costs, orbital hotels are plausible. Hell, maybe even ones on the moon. But that's as far as it will go; the trip to Mars and other far-off bodies is simply too long, too dangerous and too costly to appeal to all but the tiniest of tiny markets, far too small to support the necessary infrastructure. So a small number of hotel staff may live in space on a temporary basis, but only in a way that is completely and totally dependent on the earth.
3. Energy. Very possible. Solar power satellites are a plausible energy source. However, they can be constructed and operated robotically. In addition, it will never be cheaper to build them with extraterrestrial materials (after factoring in the costs of developing that infrastructure) than to simply launch the components from earth, especially with the declining cost and weight of photovoltaics. Thus, no humans in space required.
4. Manufacturing. Possible. Only a handful of really plausible products have been suggested, though, and none of them seem to preclude automation.
5. Antimatter. Possible, maybe? It exists in significant quantity in the Van Allen belts, but extraction, if possible, would be automated.
6. Minerals. Doubtful. Bringing inexpensive materials like nickel and iron down from orbit will never be profitable; it's just so much cheaper to extract them here, even from secondary sources, or recycle them. Precious metals from asteroids are a possibility, but they would have to be produced at low rates to avoid flooding the market; profitability is thus questionable. But even if asteroid resources were developed, again, there's no reason to do it with humans instead of robots.
7. Helium-3. Will not happen. There are many, many alternatives to He3-D fusion plants. They have various advantages and disadvantages, but none of them require going to the frickin' moon, not to mention that He3 can be produced through the lithium->tritium->He3 process.
8. Some As-Yet Unimagined Resource. Will not happen. We have the periodic table. We have spectroscopy. We have a pretty good understanding of how celestial bodies are formed. We know what's out there. Simply put, there's nothing else in space that we need on earth.
Another posited basis for space colonization is social and political demand.
One occasionally-discussed scenario is that of overpopulation and/or resource exhaustion, where earth's excess inhabitants are sent into space to relieve the pressure on our beleaguered supplies. There are a number of problems with this. The first is that earth's population is predicted to level out; somewhere in the vicinity of nine billion around 2050, last I read, an ultimately sustainable level. Second, launching a significant fraction of our denizens into outer space would be an endeavor on a simply unimaginable scale, exceeded only by keeping them alive for the many decades that it would take them to become self-sustaining. It would, without question, bankrupt a planet that, by the premise of the scenario, would already be strapped for cash. Third, most resources don't really "run out." All metals can be recycled, and nature recycles water and biomass for us. Fossil fuels run out, but alternative energy sources are being developed, and that particular exhaustion will happen too soon for space colonization to be a solution anyhow.
Some independently-minded people would like the chance to strike out into the vast frontier of outer space. These men and women imagine that they can find freedom and/or fortune beyond the reach of earth's tyrannical authorities. But they're wrong. First, as we've already established, there's no fortune in space. The challenges involved in creating a completely self-sustaining extraterrestrial settlement could be described as "beyond titanic," so any plausible colony would have to trade with earth for at least a while. Unfortunately, anything the libertarian space colonists can produce, people on earth can produce with robots for less money. So they have nothing to trade with. Furthermore, space is really the ultimate collectivist environment. When a mechanical failure in the walls of your quarters can lead to colony-wide decompression, you really have to start working as a team.
And, of course, there's the old saw of not putting all of our eggs in one basket. But even if someone put together a trillion dollars to build a self-sufficient space colony for just this purpose, at some point it would occur to them, "Hey, I could build a bunch of megabunkers a mile underground for $100 billion and still have $900 billion left over for hookers and blow!"
A further major use of outer space is for military purposes. This is already here; we have communication, positioning and reconnaissance satellites, we have anti-satellite weapons, and we may eventually have space-based weapons. The only reason to put humans in space for all of this, though, is if command and control issues make lightspeed delays unacceptable. But if there's nothing outside of earth orbit worth fighting over (and we've just established that there isn't), such delays wouldn't be an issue.
In conclusion, because of the vast expense of all but the most limited human presence in space, a definite purpose is needed to justify it; there's simply too much money involved for people to do it "because it's cool." As we've shown, there is no economic, social, political or military goal that would serve as such a justification. Therefore, space colonization will never happen.
I'd love to hear your feedback. Please tell me what I've missed, where I'm right, where I'm wrong, etc. However, please refrain from non-answers like "Humans are a nomadic species, it is in our nature to push the frontier, etc, etc...," or "But I want to live in space!!1!" I'm looking for specific, plausible mechanisms by which humans might expand into space. Thanks.