Space and the future of mankind

[bcannell]

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.

[Jens]

There have been lots of discussions on this issue. If you look around in the Space Exploration section, you will find it coming up quite frequently. I'm sure there are threads in the past that were dedicated to this issue.

I basically agree with what you've said. I think the best thing we can do is develop robotic exploration, which is relatively cheap and effective.

One argument that people will give for space colonization is to allow humanity to survive some catastrophe on earth. I don't think it's all that likely that we'll be able to create a self-sufficient colony in anywhere like the near future, so it's probably hopeless anyway, and I'm not sure it's such an important goal that we should be pouring billions of dollars into it. Just saving 100 people to repopulate the earth, if it can be repopulated, seems not so important to me. Better do what we can do to figure out how to deflect asteroids.

[Ara Pacis]

The OP refers to expense a lot and I sense that it's referring to Return on Investment and Cost Benefit Analysis. Will you quantify your cost assumptions?

[Ilya]

Here are some quantifications:

The High Frontier, Redux, also known as the web page most hated by space cadets. I strongly suggest reading all of it, including all 800+ comments. A lot of them are criticisms of the initial articles, and responses to these criticisms are especially informative.

[Swift]

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.

First, hi bcannell, welcome to BAUT.

Not to nitpick words, but I think the key open points in that sentence are "significant degree" and "future".

If by significant degree you mean a significant percentage of the human race, I would strongly agree, at least for the next several hundred years. But if by significant degree you mean, for example, a permanently manned station in LEO, with even a few hundred people, I think that is quite likely in say, the next 50 to 100 years.

Similarly, "future" is possibly a very long time. I admit no skill in predicting such. But, as I said above, I'd expect some "significant" presence in space over the next 100 years, including permanent (if not self-sustaining) bases in LEO, on the Moon, and maybe even Mars (but more doubtful).

1000 years out.... who knows. No pun intended, but I think the sky is the limit.

[IsaacKuo]

The future is a very long time. At some point in the future, the Sun will boil off the Earth's oceans and likely swallow up Earth altogether. Well before that, it will be less expensive to figure out how to live in space colonies than it will be to try and figure out how to survive on Earth.

It's one thing to say that we won't expand into space in the next century or millenium. But anyone who says it will never happen is lacking in a perspective of time.

[Ara Pacis]

Here are some quantifications:

The High Frontier, Redux, also known as the web page most hated by space cadets. I strongly suggest reading all of it, including all 800+ comments. A lot of them are criticisms of the initial articles, and responses to these criticisms are especially informative.

I'll peruse it, but meanwhile, I want to know what the OP thinks.

[Bluevision]

I agree with you OP, space isn't a very profitable business, and if it was, it'd be profitable in the degree of centuries, probably even millennia. That's why I believe space is not going to be a profit-driven business, pulled off by governments of the world, and (I like to vaguely say "the human race as a whole,") international organizations like the UN.

But I believe we're headed for space. It's a chance to push humanity further out, and by extension push nature and life further. Even if there's no monetary profit or political gain for it, humans will always want to go further.

So OP, there's no physically justifiable reason for humanity to go even beyond the ISS, but it'll happen. And you've done a beautiful job to show why capitalist space wouldn't and won't work

[Ara Pacis]

I agree with you OP, space isn't a very profitable business, and if it was, it'd be profitable in the degree of centuries, probably even millennia.

I think it might still be useful to have a discussion of cost, if the OP can provide some new argument or back up his or her claims with at least conceptual arguments if numbers are not available. I want to know how valid and how comprehensive are his cost estimates. After all, costs are measured in more than merely money.

[Jens]

It's one thing to say that we won't expand into space in the next century or millennium. But anyone who says it will never happen is lacking in a perspective of time.

I can agree here. I notice now that the OP said will "never" happen. I'd agree that never is much too strong a word to be used (it's such a strong word that maybe it should never be used).

[Skyfire]

I can agree here. I notice now that the OP said will "never" happen. I'd agree that never is much too strong a word to be used (it's such a strong word that maybe it should never be used).

I agree. Just try looking at the perspective of say the last 200 years. If you said to people 200 years ago that one day man will be able to fly, and regularly, at "reasonable cost" (related to their income, or cost to business) to many places around the world, I am sure they would have thought you mad.

If you also told them even 100 years ago that navigation could be done to the nearest 5 metres (or is it 1 metre now?) in daylight, or at night, or even in fog and bad weather, they would have said it was impossible.

Even to people of 50 years ago the idea of a phone in every pocket or handbag would just seem unlikely.

The internet that we have today with streaming video from all corners of the earth, picture bucket sites for all our holiday snaps to share with friends and family all around the globe etc etc, would still seem a long way off to early user of the internet during the 1980's or possibly even the early 90's.

The point of all this is that we're not entirely sure where technology will go in the next 10 years (although I think we have some ideas), let alone the next 50 or 100 years. As for the next 1000 years, well, all I can say is 'who knows?'

On that basis physics, cosmology, and general science may progress in unexpected directions and make radical new discoveries, that seem impossible with current knowledge.

Current knowledge shows that many ideas for space travel are extremely expensive thus making them commercially impractical. Unless and until some radical change happens to bring space travel within the realm of "reasonable cost" (related to income, or cost to business) then it is unlikely to be a commercial business.

[Skyfire]

And of course if you said to someone in 1950 that within 20 years a man would walk on the surface of the moon they would have most likely laughed at you and said "impossible!"

Sometimes you only have to look at history to discover that mankind has achieved the 'impossible' on quite a number of occasions. It is just the 'miracles' that took a little longer ...

[bcannell]

There have been lots of discussions on this issue.

I don't doubt it, but I couldn't find it to the required depth. Lots of noise when I do the searches, you know.

One argument that people will give for space colonization is to allow humanity to survive some catastrophe on earth. I don't think it's all that likely that we'll be able to create a self-sufficient colony in anywhere like the near future, so it's probably hopeless anyway, and I'm not sure it's such an important goal that we should be pouring billions of dollars into it. Just saving 100 people to repopulate the earth, if it can be repopulated, seems not so important to me. Better do what we can do to figure out how to deflect asteroids.

And crucially, as I alluded to in my post, it's never going to be cheaper to keep people alive in space than to simply bury them in an underground bunker.

The OP refers to expense a lot and I sense that it's referring to Return on Investment and Cost Benefit Analysis. Will you quantify your cost assumptions?

To a great extent I can't, of course, given the great complexity of the operations under discussion, but here's a back-of-the-envelope analysis of the lunar SPS development concept. This, I think, is by far the most plausible reason for going into space.

Cost-estimating the infrastructure to build SPSs on the moon is obviously far beyond the scope of this post or my abilities in general, but I think we can agree that it would be pretty monumental. I have trouble believing that it could be done for less than $1 trillion overnight costs, including the cost of developing the SPS technology itself - after all, NASA's estimates for a simple lunar outpost were closing on $100 billion. For such a facility we need diggers, short- and long-range transport vehicles, refineries of all kinds, photovoltaic fabs, facilities to produce the microwave transmitters and stationkeeping mechanisms and structural support, launch vehicles, launch infrastructure, crew habitation and life support systems, greenhouses, power plants, maintenance and infrastructure support for all of the above... the list goes on, and ALL of it has to to be built and rated to operate in the hostile lunar environment. But the real killer is the time scales involved: thirty years, say, from the start of development to the start of payoff? Given the unpredictability of energy costs and demand thirty years down the road, you're looking at discount rates upwards of 10%. We will generously assume 8%. That means that by the end of development, assuming the expenditure is spread evenly among those thirty years, your company is carrying around almost $3.8 trillion in debt, with annual interest payments of over $380 billion.

The current level of worldwide electricity consumption is around two terawatts, growing at a rate of about 2.5% annually. Given typical powerplant lifetimes of fifty years, this means that 90 gigawatts of new and replacement electrical capacity is installed each year. This demand will level off (or at least grow much more slowly) some time after population peaks circa 2050, at which time you're probably looking at 300 gigawatts per year. Suppose that SBSP will have an impressive market share of 50% of this new construction, or 150 gigawatts per year. Photovoltaics are already under $1/W, but will necessarily be more expensive to make on the moon; other components will be necessary as well, but we'll assume that the overall unit cost of the SPS itself is only $1/W. Therefore, our 150 gigawatts per year requires $150 billion additional investment per year. We assume zero costs for the rectenna and overall plant operations; in a relative sense, that isn't far from the truth. Now, if electricity sells at $0.10/kWh, half of which goes to our power company, then revenues work out to be $65.7 bn/yr^2. Wikipedia cites a powerplant lifetime of 20 years, though, so revenues stop growing after that time; you're just replacing old capacity.

Doing the math (with Excel, natch), we find that the debt peaks at about $5.7 trillion after nine years of operation. Debt finally declines to zero after 21 years of operation (year 51 of the project).

Needless to say, putting together almost $6 trillion of investment with a payoff time of over fifty years is a non-trivial task. Especially when you consider the alternative, launching from earth.

Assume an initial budget of $100 billion over ten years for developing the SPS technology - they aren't very complicated tech, after all. We'll assume the same 8% discount rate (though realistically the faster turnaround time should lead to a lower rate than with the lunar plan), so the debt after the development period is $145 billion. Now, I have seen estimates, based on thin film solar cells, of 1 kW/kg overall for a SPS. This is likely to decline given future progress in solar cell efficiency and the possibility of more lightweight concentrated photovoltaics, but we will use it anyway. The assumption is that the satellite components will be launched to LEO on rockets, then boosted to GEO using any of various very low cost, presumably mature "space tug" technologies (sails, ion rockets, etc), and finally assembled. At launch costs of $3000/kg (quite possibly less, given the economies of the scales we are discussing), this works out to $3/W launching from earth. We'll assume the same $1/W for the SPS itself, though it should really be cheaper than building on the moon. That makes an overall cost of $4/W. Again we will assume zero cost of rectennas/operations. To install our 150 gigawatts per year, then, will cost $600 billion per year, again with revenues of $65.7 bn/yr^2. Doing the math again, we find that debt peaks at only $5 trillion in year ten of operation and declines to zero in 28 years (year 38 of the project).

So launching from earth allows for lower peak debt and faster repayment. It's true that when debt is finally paid off, lunar production will have an advantage in facing only $150 billion annual capital expenditure rather than $600 billion. With eventual revenues of 20 * $65.7 billion = $1314 billion, this is significant: profits are $1164 billion rather than $714 billion. But remember that the earth launch group has had a thirteen year head start with profits. If they've been investing their profits at a modest 5% interest rate, they will have accumulated over $13 trillion by the time the lunar group pays off their debt! Theoretically the lunar group will eventually overtake the earth group, but I've run the numbers out to a thousand years and it still hasn't happened.

The long and short of it is that the high initial capital expenditure and long development time of a lunar production facility negate any long-term production cost advantage over earth launch.

Note that we can expand this argument to exclude lunar production for the communication satellite market, which is much smaller than SBSP but does not allow for proportional reduction in infrastructure development costs. The product technology is also already well developed, and features more varied and complex parts than SBSP, requiring more varied and complex production facilities.

I'll try to put together an analysis of the asteroid mining thing soon.

First, hi bcannell, welcome to BAUT.

Thank you.

Not to nitpick words, but I think the key open points in that sentence are "significant degree" and "future".

If by significant degree you mean a significant percentage of the human race, I would strongly agree, at least for the next several hundred years. But if by significant degree you mean, for example, a permanently manned station in LEO, with even a few hundred people, I think that is quite likely in say, the next 50 to 100 years.

Similarly, "future" is possibly a very long time. I admit no skill in predicting such. But, as I said above, I'd expect some "significant" presence in space over the next 100 years, including permanent (if not self-sustaining) bases in LEO, on the Moon, and maybe even Mars (but more doubtful).

I think those assessments are plausible. I admit that I'd be hard pressed to put forward a concrete contextual definition of "significant." Any space presence that is self-sustaining, or nearly so, would definitely be significant, while a tiny LEO/lunar space tourism market and a couple research stations would not be. But I admit that I haven't formulated a dividing line.

1000 years out.... who knows. No pun intended, but I think the sky is the limit.

I obviously can't prove what will happen in the next thousand years, but I think it's possible to show that expansion into space is highly, highly unlikely. The limit, I believe, is not technological ingenuity but simple physics, economics and geography.

The future is a very long time. At some point in the future, the Sun will boil off the Earth's oceans and likely swallow up Earth altogether.

Well, okay. You've got me there. But I think five billion years from now the inhabitants of this world, if any, are unlikely to resemble humans.

Well before that, it will be less expensive to figure out how to live in space colonies than it will be to try and figure out how to survive on Earth.

How do you figure?

I agree with you OP, space isn't a very profitable business, and if it was, it'd be profitable in the degree of centuries, probably even millennia. That's why I believe space is not going to be a profit-driven business, pulled off by governments of the world, and (I like to vaguely say "the human race as a whole,") international organizations like the UN.

But I believe we're headed for space. It's a chance to push humanity further out, and by extension push nature and life further.

I don't deny the possibility of symbolic, "flags and footprints" missions as far as Mars - perhaps even further. Even earth-dependent research stations. But there's no evidence of strong public sentiment (and make no mistake, it would have to be STRONG) to establish a real foothold there.

Even if there's no monetary profit or political gain for it, humans will always want to go further.

Which humans? How much money are they willing to spend on that goal? After all, there are a lot of people in the US who have never left the state they were born in. Some haven't even left their home county. I think most of us are actually pretty content with earth. And human nature is pretty consistent over time.

I agree. Just try looking at the perspective of say the last 200 years. If you said to people 200 years ago that one day man will be able to fly, and regularly, at "reasonable cost" (related to their income, or cost to business) to many places around the world, I am sure they would have thought you mad.

If you also told them even 100 years ago that navigation could be done to the nearest 5 metres (or is it 1 metre now?) in daylight, or at night, or even in fog and bad weather, they would have said it was impossible.

Even to people of 50 years ago the idea of a phone in every pocket or handbag would just seem unlikely.

The internet that we have today with streaming video from all corners of the earth, picture bucket sites for all our holiday snaps to share with friends and family all around the globe etc etc, would still seem a long way off to early user of the internet during the 1980's or possibly even the early 90's.

The point of all this is that we're not entirely sure where technology will go in the next 10 years (although I think we have some ideas), let alone the next 50 or 100 years. As for the next 1000 years, well, all I can say is 'who knows?'

Except for the GPS example, which is the result of new physics (semiconductors), those aren't really true. People in 1810 were thinking about flight, even heavier-than-air flight. Mobile phones had been invented by 1960, and people had noticed the semiconductor downscaling trend by then. Similar trends for bandwidth were observed by the 1980s.

I guess if you asked a random guy on the street about those things he would be incredulous, but asking an expert on the subject could very well result in a different answer.

On that basis physics, cosmology, and general science may progress in unexpected directions and make radical new discoveries, that seem impossible with current knowledge.

Current knowledge shows that many ideas for space travel are extremely expensive thus making them commercially impractical. Unless and until some radical change happens to bring space travel within the realm of "reasonable cost" (related to income, or cost to business) then it is unlikely to be a commercial business.

The new science would have to be pretty dramatic, though. Unforeseen improvements in propulsion, or materials, or life support, or manufacturing alone would be insufficient. Only a combination would be really game-changing. But certainly I'm arguing from the position of plausible technological advances without enormous changes in physics.

And of course if you said to someone in 1950 that within 20 years a man would walk on the surface of the moon they would have most likely laughed at you and said "impossible!"

Depends on whom you talked to. If you met someone who was knowledgeable about rocketry and space travel... I'm not so sure.


I should clarify that to a large extent, the purpose of all this was to show on the other message board that government policy decisions are irrelevant to future space development and space colonization because there would never be any. If it won't happen for hundreds and hundreds of years then current policy is pretty much irrelevant anyway. So I'm fairly content with that more limited conclusion.

[IsaacKuo]

I agree. Just try looking at the perspective of say the last 200 years. If you said to people 200 years ago that one day man will be able to fly, and regularly, at "reasonable cost" (related to their income, or cost to business) to many places around the world, I am sure they would have thought you mad.

I think this is the most interesting example. Replace "200 years" with "100 years", and there weren't really any fundamental breakthroughs involved...mostly just gradual improvements in the basic technology and typical economic power.

If you look at it in economic and engineering terms, it seems crazy that such an inherently inefficient method of transportation as jetliners could outmode such an inherently efficient method of transportation as ocean liners. It seems crazy to even suggest jetliners could ever be economically viable. But the world of the late 20th century had per capita energy production which was good enough to support jet transportation in the mainstream.

If something as insane as jet liner transportation can be made economically viable, why not suborbitals? Some day, sitting in a jet for the better part of a day may be as unthinkable as spending several days on an ocean liner.

[Skyfire]

I think this is the most interesting example. Replace "200 years" with "100 years", and there weren't really any fundamental breakthroughs involved...mostly just gradual improvements in the basic technology and typical economic power.

If you look at it in economic and engineering terms, it seems crazy that such an inherently inefficient method of transportation as jetliners could outmode such an inherently efficient method of transportation as ocean liners. It seems crazy to even suggest jetliners could ever be economically viable. But the world of the late 20th century had per capita energy production which was good enough to support jet transportation in the mainstream.

If something as insane as jet liner transportation can be made economically viable, why not suborbitals? Some day, sitting in a jet for the better part of a day may be as unthinkable as spending several days on an ocean liner.

Thanks Isaac for putting it so well. That was at least part of what I was trying to get at, and you have put it so much better! Thanks

[Ara Pacis]

To a great extent I can't, of course, given the great complexity of the operations under discussion, but here's a back-of-the-envelope analysis of the lunar SPS development concept. This, I think, is by far the most plausible reason for going into space.

It is difficult to go through all that complexity, but can be useful as anything less requires accepting assumptions. Perhaps that is why this reminds me of college forensics/debate where we would take a wide topic (e.g. pollution) and create an argument based on one narrow aspect of it (e.g. landmines) so as to trip up the negative side on the details which it is assumed they don't know well enough to debate effectively and, therefore, stipulate.

You mention a NASA study and perhaps I should stop you there. NASA is expensive. They do a lot of good work, but some would argue that they are too picky and too tied up in red tape to not be expensive in their operations and, therefore, their estimates. Some people would recommen the free-market. I am not one of them. I would be content to let a long-term institution, such as a government entity, run it, but I'm skeptical that NASA proposals are either the best or cheapest way.

However, NASA has done a lot of the research necessary, thus, that would not need to be replicated. For example, the NASA nose patrol has done the legwork on what paints are good for use on spacecraft interiors. We might forgo that cost on R&D and simple ask: How much would it cost to purchase one gallon, or better yet, a thousand?

It might be useful to look at John Walker's essay, "Rocket-a-Day", for inspiration. I say inspiration because some think his assumptions are naive, but his conclusion is not. Economies of scale will make a lot of things less expensive. Well made and tested turbo-pumps may never be cheap, even if made on an automated assembly line, but perhaps there are areas where it will. We might want to find another, automated way to apply the foam to external tanks other than having them lovingly hand-crafting by a highly paid labor force (or better yet, use a rocket design where there is no need to sculpt the complex curves of that ogive). And that labor force is where much of the expense and excess capacity lies (and where some cost assumptions can fail if they assume duplication of labor costs instead of fulfilling any current under-utilization).

As for the Solar Power Satellite idea, I can either take it or leave it. I suspect that if energy demand is so high and solar cells as light and efficient as to make it profitable, it will be easier and cheaper for people to put solar panels on their roofs. More efficient energy appliances will also go a long way to meeting that demand.

As I am not a space-libertarian, I am also not as interested in profit-as-motive. But I'm okay with making money, so it could be useful to look at the real costs of doing business. Today, a lot of industry, from mining to manufacturing, costs society much more than merely money. Environmental damage is one. Human misery, morbidity and mortality are others. Some argue that an asteroid or lunar deposit of -insert mineral- would be too expensive to get or would glut the market making it worthless. Ignoring the cost of acquisition for the moment, we need to consider the Total Cost of getting it from Earth, including not only the normally considered costs of acquisition of land and operating expenses, but the costs of site remediation and the medical costs of those affected by effluent and the costs of environmental degradation.

Something to consider here is the possibility of finding something in space that could be mined more efficiently or found in greater quantities than on earth. There are some rare elements that cost more than gold due to their scarecity (rare earth elements) and others which cannot be recycled effectively due to their uses (e.g. Bismuth), and might be more economically useful if they could be found in relative abundance without having to process vast quantities of crustal material to obtain a low diffusion (e.g. Lithium). As is the case with Supply-and-Demand, in some cases, there is not enough supply to meet any demand, so there is no market despite multiple potentially profitable uses.

Robert Kagan's concept of the License to Operate for businesses (explored with paper mills), concluded that aside from regulatory and commercial licenses to operate (e.g. legal and profit requirements), there is also a social license and that there is a social cost to consider when measuring operating costs. In other words, comparing resources obtained from space needs to consider the potential savings from not getting them from Earth (e.g. NIMBY). Of course, the same argument can be made for space propulsion, etc, so perhaps it is about choosing the better of two evils, but the choice is relevant.

In addition to tangible costs, intangible costs should be considered. Whether you want to call it flags-and-footprints or science-for-the-sake-of-science or because-it-would-be-cool, there are people who want to do something either themselves or vicariously through their heros. Maybe that is useful to consider for a commercial enterprise, or maybe it's not. Would Nike or Kellogg use it to promote their products like how they use athletes. Maybe. Perhaps it's not calculable that way. Then lets simplify it and let space-enthusiasts purchase bonds, give donations, have an official referendum/strawpoll or put a check-box on their tax returns on how much money they would like to be spent on space programs. If people want to pay for intangibles, help them by taking their money.

I should clarify that to a large extent, the purpose of all this was to show on the other message board that government policy decisions are irrelevant to future space development and space colonization because there would never be any. If it won't happen for hundreds and hundreds of years then current policy is pretty much irrelevant anyway. So I'm fairly content with that more limited conclusion.

Some have equated wanting space programs to religion. Perhaps that's a useful idea. If commercial entities, with their ROI cyles of years (or longer depending on government regulations and subsidies) or governments, with their elections cycles and term limits are too short, them perhaps religious institutions with their longer range goals and history of century-long construction projects might succeed. Saving future humanity from an asteroid-based extinction event may be considered a laudible and selfless goal contrary to selfish motives. Fine, let those who deal with lauding deal with the expenses of space travel... after all, peddling religion can be quite lucrative.

[Jens]

I agree. Just try looking at the perspective of say the last 200 years. If you said to people 200 years ago that one day man will be able to fly, and regularly, at "reasonable cost" (related to their income, or cost to business) to many places around the world, I am sure they would have thought you mad.

I think you have to be careful with the comparisons, though. Flying in the air is a fairly trivial problem. Birds and other creatures have been doing it quite well for a long, long time, and the engineering issues are not that complex. Navigation is also something that many living things can do quite well. I think that living in space is a much, much more complex problem.

[J Riff]

in a thousand years or three...will go forth and do the hard work...then Mankind shall spread, like an insideous fungus, and the Milky Way shall be ours !
I can't see stamping out people. Any more than an atomic war would kill all the cockroaches. Some of us will survive to get away, we will slip quietly into space and start buying up planets. )

[Sardonicone]

in a thousand years or three...will go forth and do the hard work...then Mankind shall spread, like an insideous fungus, and the Milky Way shall be ours !
I can't see stamping out people. Any more than an atomic war would kill all the cockroaches. Some of us will survive to get away, we will slip quietly into space and start buying up planets. )

The KT impact was so powerful that the energy released was on an order of magnitude more than all the nuclear weaponry in existence.

Yet...life survived. A nuclear war would probably wipe us out, however life on the whole would survive, and most assuredly, given time, make a full recovery.

Concerning the OP - as the life expectancy continues to tick ever upward, it remains to be seen whether or not the maximum world population will settle in at ~9b. I think a lot of projections concerning global population tend to gloss over the fact that medical breakthroughs are happening at a breakneck speed, such that it's possible that the life expectancy increases will outstrip the time it takes for them to come, leading to (accidents and murders aside) immortality. At that point there may be more of an incentive not only to find additional resources elsewhere, but also to start getting off our pale blue dot

[Jens]

Concerning the OP - as the life expectancy continues to tick ever upward, it remains to be seen whether or not the maximum world population will settle in at ~9b. I think a lot of projections concerning global population tend to gloss over the fact that medical breakthroughs are happening at a breakneck speed, such that it's possible that the life expectancy increases will outstrip the time it takes for them to come, leading to (accidents and murders aside) immortality.

I think that the basic idea behind the leveling off is not so much about longevity but about reproduction. In many advanced societies, the fertility rate is close to 1, so as long as people die eventually, the population will level off. Of course, if they become immortal (not likely at all, IMO), then this point becomes invalid.

As a piece of good or bad news, though, depending on how you see it, it turns out that although life expectancy itself has increased tremendously, maximum lifespan has apparently not. The longest lived people were in their 110s 100 years ago and that hasn't changed, despite medical advances.

[eburacum45]

That is because the potential of genetic technology has not yet been considered. I can understand that most people will be unwilling accept genetic alterations to human nature which affect physical characterstics for aesthetic reasons, but I find it difficult to beleve that modifications which allow a longer lifespan would be universally rejected.

If humans do acheive a longer lifespan then a stable world population of 9bn seems unlikely to persist for very long. If you reduce the death rate in a population, then you must reduce the birth rate, or increase emigration. A longer-lived population would be more likely to consider the benefits of investing in projects which would take a very long time to show a profit, such as the colonisation of the Solar System and elsewhere.

And make no mistake - the Solar System is capable of returning a great deal of profit. The Sun puts out a billion times the energy currently used by our civilisation; not counting the water locked inside the gas giants, there is at least a hundred times as much water in the solar system and surrounds as there is in the oceans of Earth, and enough of all other elements to create artificial biospheres capable of supporting trillions or quadrillions of people (depending how much crowding they are prepared to tolerate).

Admittedly the resources of the Solar System will eventually all be used, assuming even a low level of population growth; they won't 'run out', as they can be recycled using the Sun's energy, but it would be an eventual limit to growth. But the exploitation of the Solar System will take a long time, and a lot can happen to human civilisation in the interim.

[Ara Pacis]

I hope I didn't kill discussion.

Maybe the OP was looking for support or to troll upon head-in-the-cloud space-dreamers, but the long threads arguing the costs of various realistic launch programs reveals that people here are more likely to put up better arguments than other venues.

For the most part, the conclusions in the OP are valid as long as the assumptions are valid. However, it is those assumptions which I would challenge are valid or will be valid in the indeterminate future. WRT, those assumptions, I'm referring to economics and politics, not handwavium and hope.