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  #51  
Old 08-06-2019, 04:05 PM
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Even if we accept that asteroid mining will be beneficial, that's a separate issue from colonization of space. On a space mine, I doubt a human crew is worth all the resources necessary to keep the crew alive. Any space mine would depend heavily on automated equipment. AI and telepresence technologies are advancing quite fast.

Last edited by scr4; 08-06-2019 at 04:05 PM.
  #52  
Old 08-06-2019, 04:14 PM
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Even if we accept that asteroid mining will be beneficial, that's a separate issue from colonization of space. On a space mine, I doubt a human crew is worth all the resources necessary to keep the crew alive. Any space mine would depend heavily on automated equipment. AI and telepresence technologies are advancing quite fast.
That's true that it's separate, but it also plays into those spinning tin cans. Those resources can and, IMHO again will be used to make those things. I think that's the real colonization that will happen...millions, maybe billions of large (many kilometers long) spinning cans with habitats, factories, housing, farms and the works. It will allow for an easing of pressure on the planet, allow us to move much if not all of our manufacturing off planet, to create and preserve habitats in space, and give folks room to expand and grow, while also putting them closer to where the work will be. While it's true that AI and telepresense and automation will be big, I think there will still be humans in the loop for the foreseeable future. Even if there isn't, I still think humans can and will expand outward as we are able.
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  #53  
Old 08-06-2019, 04:47 PM
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In other words, it's a very soft metal that doesn't form very many chemical compounds. I suppose it would make a nice safe fishing weight.
Trust me - there are plenty of uses for cheap gold in industry that have a little more added value than fishing weights. For example, I imagine we'd see a hell of lot more gold-plated connectors. And gold-plated heat reflectors would be very common. Gold is an excellent reflector of infra-red heat. Every radiant heater might have a gold reflector behind it. But we don't know all the uses for cheap gold, because we've never had cheap gold. Once gold is cheap, we would find lots of ways to exploit its unique properties.


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No, that's not gold. Those multilayer insulations on spacecraft are made of aluminum-coated polyimide. The gold color is the color of polyimide film.
Huh. I thought the MLI has a vapor-deposited layer of gold on the outside. Ignorance fought.

However, gold is still heavily used in spacecraft - just not for thermal insolation.

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The only gold I've ever seen on spacecraft are coatings on electrical connectors and a few infrared telescope mirrors.
Space Suit visors have a gold layer to keep out infra-red radiation. Gold plated tape is used in some places.

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Cite for the heavy metal content estimate?

Can't do that, because we don't know. But if it is a planetary core remnant, it will be full of the heaviest elements that collect to make planets. It's probably mostly iron, may e 85-90%, 5% nickel or so, then smaller percentages of chromium, platinum, gold, etc. One of the reasons we need to explore it is to assay what is there.

But given the mass of the thing, even tiny percentages equals a whole lot. Let's say only .1% of it is gold. That's still 10^16 kilos of gold. So instead of having 10^13 years worth of gold at current production rates, it might only have 10^10 years.

Of course, we don't know how hard it would be to mine, where we would find it in the asteroid, etc. But the potential is certainly there to replace all our gold needs, plus our need for nickel, iron, platinum, etc. And that's just one asteroid. Whether we can figure out a cost-effective way to extract it and exploit it remains to be seen.

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Which do you think is easier, developing a cleaner mining method on earth, or developing an asteroid mining method?
There is no easy way to move hundreds of thousands of tonnes of rock. We have been gold mining for centuries, and our techniques are pretty mature. So I'm going to say asteroid mining might turn out to be much easier to do cleanly, since all we need to do is learn to do it all all. From Earth's perspective, the most wasteful mining project on an asteroid is still perfectly clean. Do you have evidence to the contrary? Are there any even theoretical gold mining techniques that are substantially cleaner than what we do now without raising costs through the roof?

There is just no way you can get around the energy requirements of moving that much rock. And then the rock has to be crushed, heated, and processed chemically to get the trace gold out of it. Then the tailings have to be transported somewhere or put back where they came from. How are you planning to do that cleanly?
  #54  
Old 08-06-2019, 05:06 PM
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However, gold is still heavily used in spacecraft - just not for thermal insolation.

Space Suit visors have a gold layer to keep out infra-red radiation. Gold plated tape is used in some places.
I'm curious where else gold (including gold plated tape) is used on spacecraft - I thought I was pretty familiar with most basic spacecraft components and I couldn't think of any. I do agree space suit visors is an example (I suppose that's technically a spacecraft).

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...There is just no way you can get around the energy requirements of moving that much rock. And then the rock has to be crushed, heated, and processed chemically to get the trace gold out of it. Then the tailings have to be transported somewhere or put back where they came from. How are you planning to do that cleanly?
I could turn around and ask, how are you planning to do all that in microgravity & vacuum?
  #55  
Old 08-06-2019, 05:22 PM
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p.s. Mining operations on Earth are dirty not because it's an insolvable problem, but because they are allowed to be. They emit as much pollution as they can get away with - why wouldn't they? They would find ways to make the process cleaner if there were any financial incentives to do so, or if they were required by regulations (which were actually enforced).

Last edited by scr4; 08-06-2019 at 05:24 PM.
  #56  
Old 08-06-2019, 05:25 PM
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I could turn around and ask, how are you planning to do all that in microgravity & vacuum?
Same question should have been asked before we started mining in the first place on Earth. We didn't know how to smelt ores, we had to learn and develop techniques.

If you are asking a poster on a messageboard for a detailed dissertation on exactly what technologies will be used in what way, and what will be developed and how to develop it, you are not framing things in a serious way.

It may be a challenge, but I see no reason why it is intrinsically harder to do it in a vacuum or microgravity, in fact, I can see a number of reasons why not having to worry about weight or insulation or contamination from or of the outside environment would make it easier.

So, I guess what would make the most sense would be to turn around and ask you why you do not believe that we can develop these technologies? What is it about micro gravity or vacuum that would prevent us from being able to smelt or refine ores?
  #57  
Old 08-06-2019, 06:01 PM
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If you are asking a poster on a messageboard for a detailed dissertation on exactly what technologies will be used in what way, and what will be developed and how to develop it, you are not framing things in a serious way.
I thought it was obviously a rhetorical question in response to a rhetorical question.

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So, I guess what would make the most sense would be to turn around and ask you why you do not believe that we can develop these technologies? What is it about micro gravity or vacuum that would prevent us from being able to smelt or refine ores?
I've spent a lot of time doing experiments and measurements in vacuum. Making mechanisms work in vacuum is inherently difficult. There is an extremely limited set of lubricants that can be used, and most of them have very high viscosity. Yet lubrication is even more important than in air. The most common cause of failure of satellites is for the mechanisms (momentum wheels and gyroscopes) to seize up. The Hubble, for example, had all 6 gyros replaced in 2009 and already half of them have failed (and they need 3 for standard operations).

Smelting is inherently dependent on gravity. Without gravity, gases don't rise and escape from the molten ore, and heavier materials don't collect at the bottom of the vessel.

All earth-moving machinery rely on gravity. All machinery for handling aggregate materials rely on gravity. Without gravity, the machinery themselves won't stay anchored to the ground. Without gravity, stuff don't stay in the bin/container/scoop, it won't stay on the conveyor belt, won't drop down when you open a hole in the bottom.

I'm sure all these are solvable problems, but I can't imagine these problems being easier to solve than the problem of reducing pollution from mines on earth.

Last edited by scr4; 08-06-2019 at 06:04 PM.
  #58  
Old 08-06-2019, 06:07 PM
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That's the way we get to an industrial base off of Earth and a potential lunar population of hundreds or maybe one day thousands of people. Add in adventurers, movie studios, rich people vacationing, and soon you've got a real, diversified economy.

But it will never be self-sufficient. It will always rely on high tech from Earth to keep it going.
I don't know why people keep on insisting on that. It will take a long time to ramp up production in space, but there's no reason that high tech couldn't eventually be produced in space. After all, here on Earth we had to invent ways to do it and gradually increase our abilities, there's no reason we would do the same in space. The first step is producing raw materials, then gradually making more and more sophisticated production facilities.
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Old 08-06-2019, 06:46 PM
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Cite for the heavy metal content estimate?
Here you go for gold. Here is platunum. I think that you will find all siderophile elements concentrated in iron, stony-iron, and undifferentiated asteroids relative to the Earth's bulk crust.
  #60  
Old 08-06-2019, 07:15 PM
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Here you go for gold. Here is platunum. I think that you will find all siderophile elements concentrated in iron, stony-iron, and undifferentiated asteroids relative to the Earth's bulk crust.
Cool, thanks.

But the largest number reported there for gold is around 10 ppm. At that concentration, we'd have to process quarter of a billion tons of ore per year, in space, to get enough gold to replace earth's current rate of production.
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Old 08-06-2019, 08:45 PM
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Cool, thanks.

But the largest number reported there for gold is around 10 ppm. At that concentration, we'd have to process quarter of a billion tons of ore per year, in space, to get enough gold to replace earth's current rate of production.
Processing in space might be more efficient. On Earth, because of gravity, you are having to deal with friction. If you want to push a large mass, you have to overcome its stiction and then continue to handle its kinetic friction to maintain movement. Alternately, you have to lift the mass and carry it. In space, you can simply give your mass a kick in the right direction and it will figure out the rest on its own.

Probably more significant than that is the cost savings in having the freedom of destruction. You don't have to worry about anyone complaining that you're strip mining or making a loud racket, etc.

(That said, there's a counter-cost added that you don't have gravity stopping shrapnel thrown off by your machinery, when you process in space. Keeping everything contained as you're shredding and melting could be a hassle.)
  #62  
Old 08-06-2019, 09:14 PM
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Mining in space may turn out to be much easier than mining on the Earth, once we are comfortable with working in space.

For example, if 16 Psyche is actually a planetary core, it may already be differentiated. in other words, the heaviest stuff is at the center.

For smaller metal-iron asteroids, one interesting technique I've heard of is to build an electromagnetic induction coil around it, then spin it. this induces eddy currents in the metal which then heats up and melts. The other thing that happens is that it will start to spin with the coil. When it gets up to coil speed, you brake the coil with retro rockets or whatever, inducing current again. Get the whole thing to melt while spinning, and centripetal acceleration will cause the heaviest, most valuable stuff to move to the surface where it can then be siphoned off.

You could also simply spot heat sections of asteroid with large solar concentrators, then simply siphon off the vapour and let it solidify.

There are many other unique ways of extracting valuable materials from asteroids. None of them have been proven out, and I'm sure there are a million devils living in the details. There's no gravity for sure, which is good and bad. So you tailor your process to take advantage of the good.

You also have a vacuum to work in, which can be a big help. We might even be able to use sputtering and directly lift the materials off the asteroid and deposit it on a substrate. Who knows? We won't know the right techniques until we have assayed candidates and testing out theoretical solutions.

But if there is enough money to be made, we will figure it out.

Last edited by Sam Stone; 08-06-2019 at 09:16 PM.
  #63  
Old 08-07-2019, 07:47 AM
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I don't know why people keep on insisting on that. It will take a long time to ramp up production in space, but there's no reason that high tech couldn't eventually be produced in space. After all, here on Earth we had to invent ways to do it and gradually increase our abilities, there's no reason we would do the same in space. The first step is producing raw materials, then gradually making more and more sophisticated production facilities.
And I don't know why people keep insisting that we can be self sufficient in space.

You'll need a base that you can maintain that can hold all of your atmosphere, and can keep all of the radiation and harmful elements that will harm you out, you'll need to maintain that.

You need to produce every nut, bold, needle, piece of cloth, cup of water, drop of lubricant, medicine, etc., etc., etc., from raw material to production. Every calorie of food. Every machine, every tool, everything. Those raw materials don't exist on the moon, and they don't exist on Mars. How do you think that is all going to happen?

Self-sufficiency is a Star Trek-ian pipe dream.

Last edited by spifflog; 08-07-2019 at 07:49 AM.
  #64  
Old 08-07-2019, 08:14 AM
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Who said anything about panic??



Sure we can. Also, WE dont' have too. There are plenty of things that could render this planet uninhabitable, or basically knock life back to perhaps some multi-cellular life forms.
There've been what, four mass extinction events since the Cambrian explosion? So eight per billion years.

Again, not feeling panicked.
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Myself, I think we need to expand our population off this planet for a variety of reasons, including it will take pressure off this planet, allow us to expand our population as much as we need too
It doesn't work like that. Populations expand to the extent that resources allow them to.
You move some people off Earth, and it will have no long-run effect on the population of Earth.

And it's not like we'll ever be able to move more than a relative handful of people off Earth anyway.
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, allow us to move much of the industry and resource gathering off planet with obvious benefits to the planet
I'll confess I'm dubious about the utility of this except for a handful of scarce metals of great utility.
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, give us room to grow, and so all our eggs aren't in one basket and make us, as well as our version of life...well, not extinction proof, but harder to have a single extinction event that wiped out everything, or a lot of things, including us.
Let's say we had a fully self-sustaining colony on some moon of Saturn, with a hundred thousand or so people. Earth, with its 7.5 billions, gets wiped out by an asteroid collision. What a relief, the human race lives on. Sorry, but I don't get why I'm supposed to care.
  #65  
Old 08-07-2019, 09:10 AM
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Originally Posted by RTFirefly
There've been what, four mass extinction events since the Cambrian explosion? So eight per billion years.
Which means we are due for 2 in the next few million years. Not that it works that way.

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Again, not feeling panicked.
And, again, I didn't say anything about panic. No need to panic. But, also, no need to bury your head in the sand. It's going to happen. Not might happen, but will happen. The only difference is that we are within maybe a century or two of being able to do something about it.

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It doesn't work like that. Populations expand to the extent that resources allow them to.
That's right, they do. And the amount of resources in the solar system dwarf anything on Earth by many, many orders of magnitude.

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You move some people off Earth, and it will have no long-run effect on the population of Earth.
You mis-understand. I'm not proposing moving the whole population off the Earth, or even a large percentage of it. Earth's population curve is already dropping. The only reason the population is still going us has to do with the baby boom. But nearly across the world people are having less kids, and by the middle of the next century the population is already going to be dropping world wide. In many countries it's below replacement levels NOW. Even the US is only above that due to immigration.

No, it will give human populations a place to expand into. I don't think you are grasping what I'm talking about. There is room for, literally, billions of 'spinning tin cans'. Not billions of people, but billions, maybe even trillions of HABITATS. That's room for not only humanity but for creating environments and habitats for most if not all of the species on the planet.

This isn't something we'll do tomorrow...or next year...or next century. It's not something we'll do in a century either. It will be more like how long did it take to build, oh, say London? Answer...it's still being built after several thousand years of change, modification and expansion.

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And it's not like we'll ever be able to move more than a relative handful of people off Earth anyway.
I disagree. We were able to move, literally, millions of people from the old world to the new world. You are thinking in terms of doing this next week, but we are talking about several centuries from now. My guess is you are also thinking in terms of moving them...not in having them voluntarily WANT to go. I'm thinking in terms of the various old world migrations to the new world, with a few people wanting something different than what their daddy, and his daddy, and his daddy had. So, Earth will still be here. People will still live here, just like they live in Europe today. Most will probably stay in fact. But millions will leave...and those millions will have kids, which is why, today, the US has a population greater than any of the parent countries their ancestors came from...we have nearly as many people as all of Europe combined, in fact.

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I'll confess I'm dubious about the utility of this except for a handful of scarce metals of great utility.
You are dubious of the utility of access to literally orders of magnitude more of basically everything we have on Earth and the ability to manufacture that stuff without damaging THIS planet? And at a time when our technology screams for raw materials (like all the stuff we need to make billions of new electric cars to supplant the ICE cars that are on the way out), or at a time when more people on the planet want and even need greater access to technology? When EVERY human will want access to technology comparable to what you take for granted?? I can't even comprehend why you'd be dubious about that, except to think that you aren't considering the fact that folks in, say, Africa, or South East Asia or Latin America WANT all the stuff you have. And that there are limits on what we can produce here on Earth, including limits due to the fact we have to live here and we don't want to damage the planet more than we already are if we can help it.

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Let's say we had a fully self-sustaining colony on some moon of Saturn, with a hundred thousand or so people. Earth, with its 7.5 billions, gets wiped out by an asteroid collision. What a relief, the human race lives on. Sorry, but I don't get why I'm supposed to care.
Because you really DON'T get what I'm saying. I'm not talking about a colony on a moon of a few thousand people. Oh, I expect that will happen, probably more like research bases or maybe manufacturing head quarters and the like. No, what I'm saying is you have, oh, say a billion 5-10 kilometer long and half a kilometer in diameter O'Neal Cylinders with, oh, say 'a few thousand' people living on each of them (well, on some of them...you'd have manufacturing on some, and perhaps habitats for different species on others).

Now, when something bad happens to the earth, do you see why you would care (not that you or I would be alive at that point of course)? You are thinking in terms of a few thousand...but the potential is there for billions or trillions of humans and pretty much every other species on the planet to live out there. And live much, MUCH better than they have it here, today. With access to resources for everyone to have the standard of living of the top tier, not the wide disparity we have today between 1st world and 2nd world and 3rd world nations.

Like I said, we are talking about thousands of years here...hundreds before we are even ready to start doing this stuff. But technological change is speeding up. While someone in the 1st Century AD couldn't really conceive of how to build, say, an 19th century steam powered iron clad or dreadnought, let alone fleets of them, we at least have an idea of what we COULD do, just not all the practical engineering on how to do it.
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Last edited by XT; 08-07-2019 at 09:11 AM.
  #66  
Old 08-07-2019, 09:18 AM
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And I don't know why people keep insisting that we can be self sufficient in space.

You'll need a base that you can maintain that can hold all of your atmosphere, and can keep all of the radiation and harmful elements that will harm you out, you'll need to maintain that.

You need to produce every nut, bold, needle, piece of cloth, cup of water, drop of lubricant, medicine, etc., etc., etc., from raw material to production. Every calorie of food. Every machine, every tool, everything. Those raw materials don't exist on the moon, and they don't exist on Mars. How do you think that is all going to happen?

Self-sufficiency is a Star Trek-ian pipe dream.
We have to do all that now. We had to build all the industries that make every nut and bolt. We had to create the agricultural practices that produce our food. We had to invent medicines and how to make them.

As far as raw materials, yes, they do exist on the moon and in asteroids and on mars.

Can you say what, specifically, it is that you see as the stumbling block that cannot be overcome?

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Originally Posted by RTFirefly View Post
There've been what, four mass extinction events since the Cambrian explosion? So eight per billion years.
And we are in the beginnings of a ninth, this one of our own making.
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Again, not feeling panicked. It doesn't work like that. Populations expand to the extent that resources allow them to.
Which is why Malthus was wrong, as he didn't understand that greater population means greater innovation which means increased access to resources.
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You move some people off Earth, and it will have no long-run effect on the population of Earth.
Depends on how you do it. Put in population controls on Earth, and tell people that want to have larger families to go to space.

Best of both worlds, Earth doesn't get overcrowded, and people who want to reproduce like rabbits are still able to.

Not to mention the ability to move mining and other manufacturing processes off world, making the Earth a more habitable place for more people.
[quote]
And it's not like we'll ever be able to move more than a relative handful of people off Earth anyway. I'll confess I'm dubious about the utility of this except for a handful of scarce metals of great utility. Let's say we had a fully self-sustaining colony on some moon of Saturn, with a hundred thousand or so people. Earth, with its 7.5 billions, gets wiped out by an asteroid collision.
[quote]
It would not be long until the bulk of humanity is living in space. Give it a couple hundred years, and the Earth, with its mere 10s of billions, may represent only a few percent.
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What a relief, the human race lives on. Sorry, but I don't get why I'm supposed to care.
This argument invalidates the argument for having children. If it doesn't matter to you if the human race goes on after you are dead, then why does it matter that your children do either?
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Old 08-07-2019, 10:21 AM
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just one thing as far as manufacturing parts goes. 3D printing has already come very far in the last 20 years. We can print in materials from soft plastic to tool grade steel now. This takes care of a lot of issues, though by no means all. I believe a lot of space habitats will be self sealing, double walled inflatable domes or if in space, spheres. The mechanics are probably the easy part of colonization. The hard part is the human body. Low grav and higher radiation is very tough on our bodies.
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Old 08-07-2019, 10:30 AM
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just one thing as far as manufacturing parts goes. 3D printing has already come very far in the last 20 years. We can print in materials from soft plastic to tool grade steel now. This takes care of a lot of issues, though by no means all. I believe a lot of space habitats will be self sealing, double walled inflatable domes or if in space, spheres. The mechanics are probably the easy part of colonization. The hard part is the human body. Low grav and higher radiation is very tough on our bodies.
That's why you spin them. And why you have large jackets of water around them. Well, plus people need to drink of course.
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Old 08-08-2019, 12:34 PM
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Low grav and higher radiation is very tough on our bodies.
I agree about high radiation, but I'm not so sure about low gravity.

Everyone extrapolates the problems of free-fall into low gravity situations, but they need not all apply. In fact the human body might thrive under Martian gravity, or Lunar gravity, better than it does on Earth. In a 1 gee environment we have problems with posture, and with falling over, and with blood pressure when standing, wear and tear on our joints, and carrying loads; on Mars or the Moon those problems could be reduced in many ways.

We may experience problems in gravity as low as the Moon's or lower, but I have a suspicion that the sweet spot for gravity is somewhere between Earth's regime and Mars' regime - and it may be closer to Martian gravity than our own.
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Old 08-08-2019, 12:56 PM
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I doubt you are alone in that, as there are a lot of 'dopers who think space is a waste of time and resources wrt human exploration and colonization. But I think you are wrong in that we could build fully self sufficient colonies in space. They wouldn't initially be so, just as the early colonization of the new world still required quite a bit of goods, especially manufactured goods, to be shipped in.
The New World already had people living in it. The colonies absolutely did not need continued support from the Old World to sustain human life; they needed support to sustain a strategic presence for European powers that were rivals with one another. People could, and did, adapt to self-sustaining lifestyles in the Americas immediately.

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But whether we are talking about spinning tin cans or colonies on other moons or planets, there is nothing stopping them from eventually being self sufficient once they reach some kind of critical mass wrt population and infrastructure.
The fact they cannot grow food is a significant barrier.
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Old 08-08-2019, 01:06 PM
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The New World already had people living in it. The colonies absolutely did not need continued support from the Old World to sustain human life; they needed support to sustain a strategic presence for European powers that were rivals with one another. People could, and did, adapt to self-sustaining lifestyles in the Americas immediately.
But they did need manufactured goods and services that they couldn't produce in the new world. In the context of their technological level verse our own (or our technological level when/if we actually go to build a colony) they are pretty comparable. After all, we can grow food in hydroponics, can produce food and water and everything else we need, assuming we have power to do so. There is nothing stopping us from making a self-sufficient colony from a technological perspective, assuming time and a desire to do so.

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The fact they cannot grow food is a significant barrier.
Um...who said you can't grow food on them?? Seriously...huh?
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  #72  
Old 08-08-2019, 01:31 PM
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The fact they cannot grow food is a significant barrier.
Why on, er, off earth would it be impossible to grow food in a constructed Earthlike environment?
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  #73  
Old 08-08-2019, 01:54 PM
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I don't know why people keep on insisting on that. It will take a long time to ramp up production in space, but there's no reason that high tech couldn't eventually be produced in space. After all, here on Earth we had to invent ways to do it and gradually increase our abilities, there's no reason we would do the same in space. The first step is producing raw materials, then gradually making more and more sophisticated production facilities.
It is a matter of manpower and diversity of materials. The supply chain for even minor products is incredibly long, and involves many people with very specialized skills.

If we were to list the supplies required to build, say, a computer chip, it would be thousands of ingredients long. If we were to calculate how many people were responsible for ultimately building that computer chip, it would run into the millions. Surviving on a hostile world indefinitely would require computer chips to be manufactured, along with millions of other goods.

In fact, it's entirely possible that our high-tech, complex society advanced at a rate limited not by invention or discovery, but simply by population size. In other words, if you landed on an exact equivalent of Earth with 100 people and all the textbooks ever written, it might take just about as long to build up to Earth-level tech as it did the first time, because to do it you need billions of people. You need people to mine materials, but before they can do that they need mining tools. Before they can have mining tools, they need to be able to smelt steel. To do that, they need sources of concentrated carbon. And on, and on it goes.

Imagine what it would take to stand up a precision chip fab, starting with no goods at all. Even on Earth such facilities cost billions, employ thousands of people, and require all kinds of exotic goods to already exist before they can even start building. Your chip fab project would employ tens of thousands of people, and that's just one thing among thousands you would need. Rubber? Where do you get that in space? What alternatives are there? Do we need to start planting rubber trees? Where does the soil come from? And the Nitrogen? Oh yeah, gotta figure out how to get that too...

Now, given infinite time of course you could make a self-sustaining colony somewhere, theoretically. But there is a serious chicken-and-egg problem: Long before it is self-sustaining there will be hundreds of thousands or millions of people there, and they will need to be supported. Who is going to support millions of people on another planet for thousands of years until they get their act together? No one.

This is the fallacy of Musk's Mars colony idea. As soon as you land the first permanent installation with people in it, you have created a cost center for Earth. There's nothing on Mars we want or need, so it's all cost and no benefit. Opposition to maintaining it would start almost immediately. Instead, you want to keep shipping more people and more facilities, increasing the annual cost, for thousands of years? It will never, ever happen.

If we want a self-sustaining space program and not another set of flags-and-footprints missions, the place to start is to figure out WHY we are doing it. And we'd better have a damned good reason that makes economic sense, or it will not continue to be developed.

Right now, the only plausible locations to profit from space are low Earth orbit, the Moon and the asteroids. Mars is a science and exploration destination, but as noted space philosopher Elton John noted, it's not a place to raise your kids.
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Old 08-08-2019, 02:01 PM
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The Moon, because if we can't make it there, we can't make it anywhere.
But the moon is BORING!
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Old 08-08-2019, 02:01 PM
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Why on, er, off earth would it be impossible to grow food in a constructed Earthlike environment?
It's not, if you have energy and feedstocks like nitrogen and phosphorous. But it will take a lot more time and effort than growing it on Earth, at least at first. That's time and effort that is extremely expensive when provided by people lifted off Earth by rockets.

Nitrogen is a real problem. It's very depleted on the Moon (unless we get lucky and find a large amount of ammonia in the permanently shadowed craters, or perhaps in some deep gas pockets or something). You need nitrogen for the plant cycle, and if you want any kind of large-scale atmosphere you need a LOT of it, or some other inert gas.
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Old 08-08-2019, 02:39 PM
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I agree about high radiation, but I'm not so sure about low gravity.

Everyone extrapolates the problems of free-fall into low gravity situations, but they need not all apply. In fact the human body might thrive under Martian gravity, or Lunar gravity, better than it does on Earth. In a 1 gee environment we have problems with posture, and with falling over, and with blood pressure when standing, wear and tear on our joints, and carrying loads; on Mars or the Moon those problems could be reduced in many ways.

We may experience problems in gravity as low as the Moon's or lower, but I have a suspicion that the sweet spot for gravity is somewhere between Earth's regime and Mars' regime - and it may be closer to Martian gravity than our own.
The problem with lower gravity is that if you grow up in low grav, then going to a planet with higher gravity can be difficult.

Personally, I like the idea that nurseries and the young would live on lower levels, and as you get older and get to retirement, you move to higher levels.

Having full gravity, or maybe a bit more, as a kid should help to build up your bones and muscles, but as we age, having a less dramatic fight with gravity getting out of bed every day would be nice.
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Old 08-08-2019, 02:52 PM
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It's not, if you have energy and feedstocks like nitrogen and phosphorous. But it will take a lot more time and effort than growing it on Earth, at least at first. That's time and effort that is extremely expensive when provided by people lifted off Earth by rockets.

Nitrogen is a real problem. It's very depleted on the Moon (unless we get lucky and find a large amount of ammonia in the permanently shadowed craters, or perhaps in some deep gas pockets or something). You need nitrogen for the plant cycle, and if you want any kind of large-scale atmosphere you need a LOT of it, or some other inert gas.
There are many carbonaceous meteorites, some even in near earth orbit that contain a lot of nitrogen. If we are ever making large spinning tin cans in space I'm fairly sure we will already have the ability to mine and transship asteroids. We won't be shipping that sort of thing from the Earth, as that sort of defeats the purpose. This pre-supposes an entire mining and production infrastructure.

But it's doable, and I think inevitable, though it's going to take centuries to build up to it. Just like it took centuries to build out our own infrastructure. We didn't have railroads and road networks in a day, it took decades, even centuries. And, as you pointed out, you are going to need a large population to do it. I think that, initially, the large spinning tin cans will be all close to the Earth (not in low Earth orbit though), as I think the Earth/Moon system will be the center of gravity, so to speak, of any sort of early industrialization and manufacturing in space. Any resources gathered from the NEO asteroids or the Moon will be here to begin with. Once you start to build the infrastructure and have the population though I see that expanding outward. There are unbelievable amounts of raw materials out there, after all...enough to build thousands, millions, even billions of habitats. You just need time, resources and the desire to do it.

Fusion would help. That's a real game changer, if it happens. But even if it doesn't, we could power this sort of thing just with what we currently have, technology wise. In a century or so, I think we will be doing this, at least the initial baby steps.
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Old 08-08-2019, 03:06 PM
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That's all great, except that it's science fiction. We have no extrapolative path today from what we are doing to having O'Neill cylinders at the Lagrange points.

Building colonies in space will require, at a minimum, a mass driver on the Moon. You would need thousands of workers on the Moon and many billions of dollars to build such a thing. You would need mass mining and refining of regolith for oxygen, aluminum, titanium, etc. For an atmosphere, you would need literally millions of tonnes of gases.

So the answer to 'where to go' is still the Moon. Maybe, one day in a few hundred or thousand years we will build colonies in space. But before we can do that, we'll need substantial investment and people on the Moon. And it's always possible that by the time we have those capabilities, O'Neill colonies won't look very enticing any more. If we can move around enough mass to build the things, and we are so good at working in space that we can construct entire colony habitats, we can probably do a lot of other things that might make more sense at the time.

In any event, building O'Neill cylinders and capturing volatiles by the billions of kg from carbonaceous chondrites is so far in the future that it has virtually no impact on the question at hand, which is "where should we start?"
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Old 08-08-2019, 03:19 PM
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That's all great, except that it's science fiction. We have no extrapolative path today from what we are doing to having O'Neill cylinders at the Lagrange points.

Building colonies in space will require, at a minimum, a mass driver on the Moon. You would need thousands of workers on the Moon and many billions of dollars to build such a thing. You would need mass mining and refining of regolith for oxygen, aluminum, titanium, etc. For an atmosphere, you would need literally millions of tonnes of gases.

So the answer to 'where to go' is still the Moon. Maybe, one day in a few hundred or thousand years we will build colonies in space. But before we can do that, we'll need substantial investment and people on the Moon. And it's always possible that by the time we have those capabilities, O'Neill colonies won't look very enticing any more. If we can move around enough mass to build the things, and we are so good at working in space that we can construct entire colony habitats, we can probably do a lot of other things that might make more sense at the time.

In any event, building O'Neill cylinders and capturing volatiles by the billions of kg from carbonaceous chondrites is so far in the future that it has virtually no impact on the question at hand, which is "where should we start?"
lol, it's ALL science fiction at this point. Even your proposals for mining on the Moon are only theoretical at this stage. We have worked with, on small scales, regolith analogs, and we've been to the Moon so know a bit about what's there, but we haven't actually tried to build any of this yet, so it's all theoretical science fiction. Also, the OP didn't ask where we should start, the OP asked what's the best place for a self sufficient colony. And I don't think that is the Moon. I agree, we will start with the Moon...I expect both mining and resource exploration and exploitation as well as things like research bases to be there. And probably a good number of people, though nothing like a colony, and probably nothing like thousands, at least not on the time scale you are talking about if we aren't talking hundreds of years. Automation is going to be in heavy use, IMHO, on any sort of Moon mining operation, with a few humans to support that. But if we are talking about several hundred years down the road, I think the best place to colonize will be something like O'Neal cylinders or their equivalent.

The thing is, if you went back, say, 200 years ago, and asked folks about transshipping the levels of material they do today, what do you suppose their answers would be? Or transshipping the levels of goods and materials we currently do across the continent, or Europe, Asia or where ever. You make billions of kg sound like it's impossible, but you need to put that figure in context. We ship, world wide, over 200 million cargo containers alone, each one weighing many tons...and that's only a fraction of the total. Shipping even one of those 200 or 300 years ago would be a huge challenge. We aren't even at the point of having small colonies in the new world level yet wrt space. But in 200 or 300 years? People would probably be laughing at the notion that shipping a few billion kg of whatever through space is some insurmountable, impossible dream.
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Old 08-08-2019, 04:05 PM
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lol, it's ALL science fiction at this point. Even your proposals for mining on the Moon are only theoretical at this stage.
It's science fiction in the sense that it involves science and we haven't done it yet. But the path I'm talking about can be extrapolated from current technologies, and requires no magic unobtanium or magic space drives or capabilities that are so far from where we are that we have no idea if we can even do them.

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We have worked with, on small scales, regolith analogs, and we've been to the Moon so know a bit about what's there, but we haven't actually tried to build any of this yet, so it's all theoretical science fiction.
There's a big difference between, "Maybe our process that works in a lunar regolith simulant on Earth will have some bugs when we try it on the Moon", and "We'll just build giant colonies in orbit using millions of pounds of material we will harvest and ship."

The former has a path you could actually define today and carry out. The other does not, and won't in our lifetimes. By your definition, any not-yet-completed engineering project involves 'science fiction' until it's finished.

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Also, the OP didn't ask where we should start, the OP asked what's the best place for a self sufficient colony. And I don't think that is the Moon.
The Marius Hills Lava Tube, which has an open skylight, has on the order of 50 square kilometers of protected space. The height and width of the tube are on the order of an O'Neill colony, but it's 50 km long. And that's just the part we've identified - it may be much bigger. And it's only one of about 200 open skylights we've already discovered. How many lava tubes do you think we haven't discovered yet because they never developed a skylight, or because we haven't seen the skylight yet.

A study from Purdue showed that lava tubes of the right shape could be stable as much as 5 km wide with a ceiling maybe 1 km overhead. If we found something like that, and it was 100 km long (even lava tubes on Earth can be longer), you could put millions of people in it. What advantage does an O'Neill cylinder have that this lava tube wouldn't have? Assuming we can adapt to low gravity, it seems crazy to turn our backs on hundreds of pre-made living spaces the size of O'Neill Cylinders, rather than ship the mass to a Lagrange point and build them there.

GRAIL found that the lunar crust is about 12% void space. It is literally riddled with tubes and caves. They have constant, nice temperatures (-20C isn't bad when there's no air to conduct heat - in fact, it will make it easier to shed heat from people and processes). They've been stable for billions of years, are fully protected from everything including solar storms, meteor impacts and the like.

Why wouldn't these be the first place you'd colonize?


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I agree, we will start with the Moon...I expect both mining and resource exploration and exploitation as well as things like research bases to be there. And probably a good number of people, though nothing like a colony, and probably nothing like thousands, at least not on the time scale you are talking about if we aren't talking hundreds of years.
We will have exactly as many people on the moon as are required for the economic and scientific exploitation of lunar resources. I can imagine hundreds in a couple of decades or so, maybe thousands at some point this century. Or maybe we'll do it with five people and robots. The future is unpredictable. But any colony needs to have a reason to exist. We aren't just going to do it for yucks. Right now, the Moon is the only place where you can conceive of a near or medium term need for more than a handful of people. So if a colony starts anywhere, the betting money is that it will start on the moon.

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Automation is going to be in heavy use, IMHO, on any sort of Moon mining operation, with a few humans to support that. But if we are talking about several hundred years down the road, I think the best place to colonize will be something like O'Neal cylinders or their equivalent.
But we aren't. I could build you a plausible future that would have us mining regolith for oxygen and water within 20 years. And I agree - it will be mostly automated, and plans are already being drawn up and prototypes built for lunar mining equipment.

In 20-40 years, I think you could see a lunar population like this: 20-50 people at one of the poles, working on mining ice and building solar installations on a crater rim to power the operation. Bases on the moon run by China, the U.S., and maybe another major power. Maybe 20-30 more people. An industrial shared hub somewhere, leasable by corporations to develop lunar techniques and house maintenance people, etc. Maybe another 50 people in total. Then various other people like movie productions, private exploration for resources, etc. Maybe a couple of hundred people in total, scattered across various facilities. Sort of like Antarctica today.

But if breakthroughs are made or resources discovered that increase the profitability of moon operations, that number could grow very quickly. A good analogy is a deep sea platform. They cost billions to build, and fifty years ago they were still experimental and only a couple had been built. Now there are close to a thousand such platforms, and even though they are highly automated they have 50-200 people on them, on average. That's on the order of a hundred thousand people now living on oil platforms on the ocean.

If something as profitable as oil was found on the moon, you could easily see that number of people going there to exploit it. If we had a trillion dollar asteroid mining economy, the moon could easily generate tens of billions of dollars per year in profit providing fuel.

Space colonies by definition have no resources of their own. All they would ever have to sell is whatever people could make there. And since they are going to be under Earthlike gravity, it's hard to think of anything that could be made there that would be worth the cost of shipping the materials to make it to the colony, then shipping the finished goods elsewhere. O'Neill originally thought that the value would be in the real estate, since Malthusian thinking was all the rage at the time. But the Earth has plenty of living space, and will continue to do so. So the colonies have to provide something of value to get the money needed to build and maintain them.

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The thing is, if you went back, say, 200 years ago, and asked folks about transshipping the levels of material they do today, what do you suppose their answers would be? Or transshipping the levels of goods and materials we currently do across the continent, or Europe, Asia or where ever. You make billions of kg sound like it's impossible, but you need to put that figure in context. We ship, world wide, over 200 million cargo containers alone, each one weighing many tons...and that's only a fraction of the total. Shipping even one of those 200 or 300 years ago would be a huge challenge. We aren't even at the point of having small colonies in the new world level yet wrt space. But in 200 or 300 years? People would probably be laughing at the notion that shipping a few billion kg of whatever through space is some insurmountable, impossible dream.
We ship that stuff in extremely energy efficient ways. We ship heavy stuff on the ground and water, where the only energy price we have to pay is the friction of moving it horizontally. That's a far cry from moving billions of kg of mass around in space, especially given the limits of the rocket equation - even with nuclear rockets.

Last edited by Sam Stone; 08-08-2019 at 04:07 PM.
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Old 08-08-2019, 04:32 PM
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Remote controlled robots could do a lot of the work. By the time we are ready to start building this stuff, we'll have robots that are capable of semi-autonomous action, and teams of people on Earth ready to step in if they encounter problems the tiny robot brains couldn't solve. The moon is only a second away by radio message, so the response times should be quite good (compared to Mars, where commands take many minutes to arrive). Forget Mars, Mercury, Europa, Titan; they are all targets for the distant future. The moon is a near-future goal.

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Old 08-08-2019, 04:58 PM
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Space colonies by definition have no resources of their own. All they would ever have to sell is whatever people could make there. And since they are going to be under Earthlike gravity, it's hard to think of anything that could be made there that would be worth the cost of shipping the materials to make it to the colony, then shipping the finished goods elsewhere. O'Neill originally thought that the value would be in the real estate, since Malthusian thinking was all the rage at the time. But the Earth has plenty of living space, and will continue to do so. So the colonies have to provide something of value to get the money needed to build and maintain them.
The only resources they have are all of the metals and organics and volatiles that they are sitting on. That's not nothing.

Not all spinning cans are O'Neill cylinders. The only parts that would be under Earth Like gravity would be the areas where people live. Manufacturing can either take place in the middle, or even on a completely separate facility that is co-located with it. You are generally going to want to build these on or in asteroids for protection from radiation and space junk, (and for them being close to mine) so the way I see it playing out is that you have the habitat in a spinning cylinder that is buried under the surface, and most of the manufacturing, especially what benefits form zero g, on or around the surface.
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We ship that stuff in extremely energy efficient ways. We ship heavy stuff on the ground and water, where the only energy price we have to pay is the friction of moving it horizontally. That's a far cry from moving billions of kg of mass around in space, especially given the limits of the rocket equation - even with nuclear rockets.
The rocket equation is a real pain for getting off the Earth, or the moon for that matter. The rocket equation does not have the same effect when you are not escaping a gravity well. Moving materials from one asteroid mine/colony to another actually requires very little in the way of delta-V. If it is just materials, and nothing perishable like people, and it doesn't matter how long it takes, it can be done with a few mere meters per second.

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  #83  
Old 08-08-2019, 05:09 PM
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The only resources they have are all of the metals and organics and volatiles that they are sitting on. That's not nothing.

Not all spinning cans are O'Neill cylinders. The only parts that would be under Earth Like gravity would be the areas where people live. Manufacturing can either take place in the middle, or even on a completely separate facility that is co-located with it. You are generally going to want to build these on or in asteroids for protection from radiation and space junk, (and for them being close to mine) so the way I see it playing out is that you have the habitat in a spinning cylinder that is buried under the surface, and most of the manufacturing, especially what benefits form zero g, on or around the surface.


The rocket equation is a real pain for getting off the Earth, or the moon for that matter. The rocket equation does not have the same effect when you are not escaping a gravity well. Moving materials from one asteroid mine/colony to another actually requires very little in the way of delta-V. If it is just materials, and nothing perishable like people, and it doesn't matter how long it takes, it can be done with a few mere meters per second.
Exactly. We aren't even talking about having to have this stuff move all that fast...not like the minerals or volatiles will spoil. I'm not sure what Sam was even thinking there, to be honest. Assuming...which is, of course, a huge assumption...that we could start mining a near Earth asteroid...you don't need all that much delta V to get it back to an orbit with the Earth. And since we have already agreed there are volatiles there, then even conventional rockets, refued in situ, could do the trick, especially if you don't mind waiting some time for them to come. We aren't going to be building millions or billions of spinning tin cans tomorrow, after all...like Rome, this stuff is going to be built over centuries, not days or even years. We build one first...then another and another. Before you know it, you have populated a whole continent, or in this case, you've built out all the best spots in the various useful Earth/Moon orbits.

And this leaves aside nuclear propulsion, or things like fusion. This is just with what is plausible and current today. Of course, today we don't need those resources or those habitats. The cost to benefit is no where near there for even the mining of the moon part. Today, we MIGHT do a moon base station for a few scientists and astronauts, and we MIGHT do a space station in orbit around the moon. But in 50 or 100 years? Costs might come down, and a need might be there. Eventually folks are going to look up at the huge profits that could be gotten from the levels of materials available and say, yeah...we could do that. You wouldn't get the California Gold Rush in, say, 1000 AD because, even if they knew the gold was there it wouldn't make any sort of sense to even try to go get it. Even in 1492, if the Spanish KNEW the gold was there they couldn't plausibly go get it. It would have been impossible.
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Old 08-08-2019, 05:39 PM
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The only resources they have are all of the metals and organics and volatiles that they are sitting on. That's not nothing.
All of which had to be imported to the space colony, since it was built from nothing. And if any of it is sold, it has to be re-imported. The point is that there are no natural resources at a space colony to exploit. Unlike the moon, where there is essentially unlimited iron, aluminum, titanium, magnesium, silicon, oxygen, and water. These can be turned into rocket fuels (Aluminum-Oxygen, hydrolox, etc) and launched to low Earth orbit or lunar orbit for a fraction of the energy, and therefore could be highly profitable.

What is there on a space station that could generate enough profit to pay for its own maintenance and whatever the people need to import to stay alive and be happy? Maybe in a couple of hundred years there will be lots of things - maybe we'll treat them like cruise ships and they'll be filled with tourists. But they HAVE to have a reason for existing, measured in economic terms, or there is no reason to build them.

Maybe zero-g manufracturing will be a thing. Maybe we'll make a bunch of discoveries of goods that are highly desirable but can only be made in zero-g. Maybe we'll start building orbital manufacturing facilities in a decade after a huge discovery like that. But if we did, that would be even more reason to go to the moon, because we'll need a lot of mass in orbit and it's extremely expensive to send it from Earth.


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Not all spinning cans are O'Neill cylinders. The only parts that would be under Earth Like gravity would be the areas where people live. Manufacturing can either take place in the middle, or even on a completely separate facility that is co-located with it. You are generally going to want to build these on or in asteroids for protection from radiation and space junk, (and for them being close to mine) so the way I see it playing out is that you have the habitat in a spinning cylinder that is buried under the surface, and most of the manufacturing, especially what benefits form zero g, on or around the surface.
Maybe. But we are so far from being able to hollow out asteroids and build bases in them that by the time we do that the economy will likely be so different that we don't know what we'll need and want at that time. Maybe we'll have automated facilities and mass drivers shooting huge quantities of mass into lunar orbit, where robotic 3D printing robots spin it into huge floating complexes essentially for free.

That's why I'm not too interested in talking about what a space colony might look like in hundreds of years. No one knows. No one knows what our needs will be then, what our tech will look like, how wealthy we are, or a host of other things that we need to know to be able to even remotely predict what the future of space will be like.

If you're writing a science fiction story, all of this is fair game, and they are all good ideas. But if we are talking about things that should affect NASA policy now, or trying to debate where we should be investing our resources to make effective use of space, that stuff is all completely irrelevant. We have to start with economics, with what is do-able now, and with feasible plans to get there from here. That's what I'm talking about. Practical plans, not speculation about a distant future that is probably no more accurate than random guesses. If you had asked people in 1800 how people will live in 2020, do you think any of them would have been even remotely close?

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The rocket equation is a real pain for getting off the Earth, or the moon for that matter. The rocket equation does not have the same effect when you are not escaping a gravity well. Moving materials from one asteroid mine/colony to another actually requires very little in the way of delta-V. If it is just materials, and nothing perishable like people, and it doesn't matter how long it takes, it can be done with a few mere meters per second.
The basis of the rocket equation is the fact that rockets work by throwing mass out the back. So every mass you want to manipulate requires another mass to be accelerated to do it. If you want to do it quickly, it can require many multiples of the mass you want to manipulate. But even if you do it slowly, you still need extra mass to do it.
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Old 08-08-2019, 05:58 PM
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All of which had to be imported to the space colony, since it was built from nothing. And if any of it is sold, it has to be re-imported. The point is that there are no natural resources at a space colony to exploit. Unlike the moon, where there is essentially unlimited iron, aluminum, titanium, magnesium, silicon, oxygen, and water. These can be turned into rocket fuels (Aluminum-Oxygen, hydrolox, etc) and launched to low Earth orbit or lunar orbit for a fraction of the energy, and therefore could be highly profitable.
Where do you think taht we would be building these things, just in the depths of space? You'd be building them on or near asteroids, and that is where you would be getting resources.
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What is there on a space station that could generate enough profit to pay for its own maintenance and whatever the people need to import to stay alive and be happy? Maybe in a couple of hundred years there will be lots of things - maybe we'll treat them like cruise ships and they'll be filled with tourists. But they HAVE to have a reason for existing, measured in economic terms, or there is no reason to build them.
What is there on the planet that does this? People make their own economies. In the short term, manufacturing satellites and other space structures that we are currently spending thousands of dollars a kilogram to get up there. If it's worth that much to put it up there, if you can find a cheaper way to build it up there, then you have cornered the market.

Once you have a critical mass, the economy comes from people buying and selling things to other people.
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Maybe zero-g manufracturing will be a thing. Maybe we'll make a bunch of discoveries of goods that are highly desirable but can only be made in zero-g. Maybe we'll start building orbital manufacturing facilities in a decade after a huge discovery like that. But if we did, that would be even more reason to go to the moon, because we'll need a lot of mass in orbit and it's extremely expensive to send it from Earth.
Right, but I'm not talking about sending it from the Earth, I'm talking about getting it from the rock that you are sitting on.
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Maybe. But we are so far from being able to hollow out asteroids and build bases in them that by the time we do that the economy will likely be so different that we don't know what we'll need and want at that time. Maybe we'll have automated facilities and mass drivers shooting huge quantities of mass into lunar orbit, where robotic 3D printing robots spin it into huge floating complexes essentially for free.
You don't need to "hollow out" an asteroid. Most asteroids are going to have the consistency of Mica at best. Unless quite a bit changes, then we will need goods and services, the same as we have always needed.
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That's why I'm not too interested in talking about what a space colony might look like in hundreds of years. No one knows. No one knows what our needs will be then, what our tech will look like, how wealthy we are, or a host of other things that we need to know to be able to even remotely predict what the future of space will be like.
Looking out that far can be fun, but I agree, we are talking more near term here. That doesn't change anything. Asteroids are still easier to get to, and from, than the moon.
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If you're writing a science fiction story, all of this is fair game, and they are all good ideas. But if we are talking about things that should affect NASA policy now, or trying to debate where we should be investing our resources to make effective use of space, that stuff is all completely irrelevant. We have to start with economics, with what is do-able now, and with feasible plans to get there from here. That's what I'm talking about. Practical plans, not speculation about a distant future that is probably no more accurate than random guesses. If you had asked people in 1800 how people will live in 2020, do you think any of them would have been even remotely close?
Find a way to make crude metals out of asteroids, and use that as trusses in satellites, saving hundreds of millions a year in launch costs. Work your way up from there.
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The basis of the rocket equation is the fact that rockets work by throwing mass out the back. So every mass you want to manipulate requires another mass to be accelerated to do it. If you want to do it quickly, it can require many multiples of the mass you want to manipulate. But even if you do it slowly, you still need extra mass to do it.
Right, but when we are talking about hohmann transfer orbits, we are talking about pretty tiny amounts of delta-v, probably more than an order of magnitude less than what is needed to get off the moon, much less the Earth.
  #86  
Old 08-09-2019, 04:11 PM
Sam Stone is offline
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Originally Posted by k9bfriender View Post
Where do you think taht we would be building these things, just in the depths of space? You'd be building them on or near asteroids, and that is where you would be getting resources.
No, we are talking about O'Neill colonies, which are literally metal cans built in space. The idea is that you build a mass driver on the moon, then start shooting material to the Lagrange points, where they will be stable for long periods of time. Then crews or automation take all that mass and turn it into giant enclosed cylinders. The cylinders rotate, and people live on the inside surface under artificial gravity provided by centripetal acceleration. Large mirrors are used to deflect light into the interior, and now you have a habitat for thousands of people. Repeat as needed.

This idea was big in the 1970's and 1980's, but the assumptions behind it are, IMO, no longer valid. And I never did understand what their economic benefit would be. I think originally the idea was that the Earth was going to be heavily overpopulated, leading to constricted living spaces, food rationing, etc. These colonies would then grow food, and would have limitless space (you just build more as needed), and you could ship food to Earth cheaply since you are sitting at the top of Earth's gravity well.

None of those assumptions are true any more.

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What is there on the planet that does this? People make their own economies. In the short term, manufacturing satellites and other space structures that we are currently spending thousands of dollars a kilogram to get up there. If it's worth that much to put it up there, if you can find a cheaper way to build it up there, then you have cornered the market.
Earth has so much abundance that we take for granted how much we get for free. You can certainly have an internal economy in a space habitat, but you also are going to require huge amounts of very expensive imports. That means you have to have something to trade. Maybe some unique product can be made there, or tourism will be huge. But right now, we know of nothing a space colony could produce that would justify the massive expense and resources required to build one.

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Once you have a critical mass, the economy comes from people buying and selling things to other people.
You still need to import a lot of things. Very expensively. A space colony will always need to buy and sell things. You can't have a services-only economy when you need to import billions of dollars in stuff every year to stay alive.

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Right, but I'm not talking about sending it from the Earth, I'm talking about getting it from the rock that you are sitting on.
Assuming an 'asteroid colony'. And all asteroids are depleted in something. Unless you master the magic transmutation of materials, you'll always be importing. A metal rich asteroid has lots of metal, but possibly no volatiles at all, or trace amounts. Now you have to find or buy water, nitrogen, sulfur, hydrogen, potassium, phosphorous... And the list goes on. And getting that stuff out to the asteroids will not be cheap.

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You don't need to "hollow out" an asteroid. Most asteroids are going to have the consistency of Mica at best. Unless quite a bit changes, then we will need goods and services, the same as we have always needed.
I really don't see people colonizing the asteroids. I think an asteroid mine would be a lot more like a deep-sea platform: A bunch of specialists in a facility running the machinery until the profitable stuff is used up, then the facility moves to the next one. Imagine a SpaceX Starship that is about to be retired because its engines are getting near their design life. So a company buys it, retrofits it with mining gear and living quarters, and sends it out to the asteroids. The crew can anchor on a candidate then explore it, take samples, and as much as 50 tons of valuables, then heads back to either a major depot in the asteroids where it drops its load and refuels, then goes out again. The engines only need to use a tiny amount of rated power, so they ladt for a long time.

But no one is going to live out their life on an asteroid. At least, not soon.

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Looking out that far can be fun, but I agree, we are talking more near term here. That doesn't change anything. Asteroids are still easier to get to, and from, than the moon.
Totally disagree. A very few asteroids are easier to get to than the lunar surface in terms of energy, but that's not the only criterion. With minimum energy transfer orbits they take years to get to. The distance means we can't manually control robots from Earth as we can if they are on the moon. There is a lot less available solar energy.

The Moon doesn't take much to land and take off from. SpaceX says that they can actually fly to the moon, land their Starship, and fly back with 50 tonnes of cargo both ways. It requires in-space refuelling, But the entire system is reusable so the cost of landing on the moon and taking off is very small - less than a million dollars.

Now consider a Starship mission to the outer planets or asteroids. First thing: you are tying up a $220 million dollar spaceship for years. That alone would make it far more expensive than going to the moon.

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Find a way to make crude metals out of asteroids, and use that as trusses in satellites, saving hundreds of millions a year in launch costs. Work your way up from there.
Satellites don't need a lot of trusses, They are mostly as compact as they can be, and packaged with high tech materials.

Also, we have to consider the economic impact of the coming generation of reusable rockets. If Starship delivers on even most of its promise, We will eventually be at the point where the mass of a satellite and its launch cost will be a small fraction of what they are now.

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Right, but when we are talking about hohmann transfer orbits, we are talking about pretty tiny amounts of delta-v, probably more than an order of magnitude less than what is needed to get off the moon, much less the Earth.
Not even remotely true, except for a small subclass of near Earth asteroids.

Let's assume Ceres, or a similar asteroid in the asteroid belt.

It takes about 11.8 km/s of Delta V to get from the surface of the Earth to Geostationary Transfer Orbit. You have to do that for both the Moon and Ceres. For the Moon, you then need to get into lunar capture, circularize and drop into LEO, then down to the surface. All of that takes about another 3.2 km/s, or 5.7 km/s from LEO.

For Ceres, you have to get to Earth Escape, then trans-Ceres injection, then when you get there you have to get into a capture orbit, then down to LCO. Here's a NASA page showing the total Delta-V for Ceres from Low Earth Orbit: Hohmann Transfer to Ceres by Launch Window. You can see that the Delta-V is between 9 and 10 km/s. And the travel time is typically over three years. There's a reason why NASA uses complex gravity-assist trajectories to get to the outer planets and asteroids. Because it takes a lot of energy to get there, even in a Hohmann transfer orbit. Almost twice as much as to land on the Moon.

So to get to Ceres, you need more Delta-V than getting to the surface of the Moon, and it takes three years instead of three days. So equivalent resources on the moon could be harvested and delivered to LEO cheaper than they could from Ceres.

Now, there are a handful of Near Earth Asteroids that are closer in terms of Delta-V. But they are all quite small and we have no idea if there is anything valuable there. All the rest of them are a LONG way away, and require huge amounts of energy to get there and back. Even more so than Mars, because at Mars you can use aerobraking. At an asteroid, not so much.

And when doing economics, that 3.5 year travel time is pretty daunting. Any money invested in the hardware is going to require seven years from launch at minimum to get anything back. Tying up a billion dollars for a decade would probably incur more in carrying costs than the entire fuel cost of flying to the moon, landing, and coming back.

Eventually, I imagine we could see facilities out there that never come back, but just keep sending back regular amounts of cargo. At that point, it might make sense. But until we are at the point of operational mining, just exploration and learning through iteration will take decades when every round-trip takes seven years or more.

Again, a lot of this stuff (and the O'Neill cylinders) were considered before the Moon because our view of the Moon post-Apollo was that it was a dry, dusty rock with nothing of interest and where everything people need would have to be imported. That's no longer our view of the moon. We are increasingly seeing it as a relatively wet world with all sorts of potential resources. The existence of extensive water changes the entire game when it comes to the exploitation of the Moon. But it takes a long time for new data to make its way into the zeitgeist of an entire industry, so most people still dismiss the moon as uninteresting.

Last edited by Sam Stone; 08-09-2019 at 04:15 PM.
  #87  
Old 08-09-2019, 06:41 PM
k9bfriender is offline
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Quote:
Originally Posted by Sam Stone View Post
No, we are talking about O'Neill colonies, which are literally metal cans built in space. The idea is that you build a mass driver on the moon, then start shooting material to the Lagrange points, where they will be stable for long periods of time. Then crews or automation take all that mass and turn it into giant enclosed cylinders. The cylinders rotate, and people live on the inside surface under artificial gravity provided by centripetal acceleration. Large mirrors are used to deflect light into the interior, and now you have a habitat for thousands of people. Repeat as needed.
Those are *a* type of space habitat, but they are not the only ones. Since then, we've learned more about the hazards of space.
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This idea was big in the 1970's and 1980's, but the assumptions behind it are, IMO, no longer valid. And I never did understand what their economic benefit would be. I think originally the idea was that the Earth was going to be heavily overpopulated, leading to constricted living spaces, food rationing, etc. These colonies would then grow food, and would have limitless space (you just build more as needed), and you could ship food to Earth cheaply since you are sitting at the top of Earth's gravity well.
those are some of the possible benefits, but not all.
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None of those assumptions are true any more.
I agree we have plenty of room, but there are those who feel otherwise.

At some point, we are probably going to implement some sort of population control measures, whether we actually need them or not. One of the ways to get around having the govt tell you how many kids you can have would be to leave the Earth and go where you are allowed to have as many as you like.
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Earth has so much abundance that we take for granted how much we get for free. You can certainly have an internal economy in a space habitat, but you also are going to require huge amounts of very expensive imports. That means you have to have something to trade. Maybe some unique product can be made there, or tourism will be huge. But right now, we know of nothing a space colony could produce that would justify the massive expense and resources required to build one.
I agree that just going out and building one for no reason is a bad idea. But, building up to it is what we should be working on, and at some point, it will become a cost effective proposal.

Before we even start doing this, we do need to have fairly extensive space manufacturing capabilities. Those can be developed for other economically viable purposes.
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You still need to import a lot of things. Very expensively. A space colony will always need to buy and sell things. You can't have a services-only economy when you need to import billions of dollars in stuff every year to stay alive.
High tech items, like high end CPUs and the like, sure. It's going to be a while before a space colony can produce the next Intel Processor. But those are lightweight and easy to transport from Earth, unlike bulk materials like iron or water.
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Assuming an 'asteroid colony'. And all asteroids are depleted in something.
Why?
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Unless you master the magic transmutation of materials, you'll always be importing. A metal rich asteroid has lots of metal, but possibly no volatiles at all, or trace amounts. Now you have to find or buy water, nitrogen, sulfur, hydrogen, potassium, phosphorous... And the list goes on. And getting that stuff out to the asteroids will not be cheap.
If the rock you are on is short on something, you don't have to get it from Earth, you can trade with another rock that has an abundance of what you need and a shortage of what you have an abundance of.
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I really don't see people colonizing the asteroids. I think an asteroid mine would be a lot more like a deep-sea platform: A bunch of specialists in a facility running the machinery until the profitable stuff is used up, then the facility moves to the next one. Imagine a SpaceX Starship that is about to be retired because its engines are getting near their design life. So a company buys it, retrofits it with mining gear and living quarters, and sends it out to the asteroids. The crew can anchor on a candidate then explore it, take samples, and as much as 50 tons of valuables, then heads back to either a major depot in the asteroids where it drops its load and refuels, then goes out again. The engines only need to use a tiny amount of rated power, so they ladt for a long time.
That would be how I would see things starting too.
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But no one is going to live out their life on an asteroid. At least, not soon.
Agreed, but soon is relative. And soon comes much sooner if we actually work towards it, rather than consider it beyond our current reach.
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Totally disagree. A very few asteroids are easier to get to than the lunar surface in terms of energy, but that's not the only criterion. With minimum energy transfer orbits they take years to get to. The distance means we can't manually control robots from Earth as we can if they are on the moon. There is a lot less available solar energy.
That's why I said you have to be choosy about your windows. They do pass close enough to the Earth, from time to time, to take a reasonable amount of time. It would certainly be longer than a moon mission, but still shorter than to Mars.

Two things, I was proposing a manned mission here, so light lag isn't an issue, and I do think that AI has more than advanced enough that things can operate with only minimal inputs, for autonomous missions.

There would only be less solar energy if you chose an NEA that had a very eccentric orbit. And, in any case, one of the technologies we need to develop is nuclear power in space. Assuming we don't have fusion (or it's just 50 years away, really, really this time), fission should still be perfectly viable, with plenty of uranium and thorium in asteroids to use, though it will be interesting engineering to build them to deal with varying gravitational situations.
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The Moon doesn't take much to land and take off from. SpaceX says that they can actually fly to the moon, land their Starship, and fly back with 50 tonnes of cargo both ways. It requires in-space refuelling, But the entire system is reusable so the cost of landing on the moon and taking off is very small - less than a million dollars.

Now consider a Starship mission to the outer planets or asteroids. First thing: you are tying up a $220 million dollar spaceship for years. That alone would make it far more expensive than going to the moon.
Considering that a big body airliner costs in the same ballpark as the Starship, I'm not all that worried about it. We'll build a bunch of them, and they will have some specializations to them. Once we start building them, the company that is building them wants to keep building them, or it loses money.

I'm not too sure how much longer SpaceX is gonna make it though. They've done some impressive things, even if rarely holding to timelines or budgets, but space is definatly in one of those "second mouse" industries rather than "early bird".
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Satellites don't need a lot of trusses, They are mostly as compact as they can be, and packaged with high tech materials.
They have quite a number of structural parts. They are made a compact as they can be in order to fit inside the fairing they are launched from, not because they want to be compact. In fact, many satellites have very complex mechanisms to unfold solar panels and equipment that had to pack into the launch vehicle. You can have a perfect launch, perfect telemetry, but one stuck hinge can endanger the whole project. You know how close we came to not having a Galileo mission because of some stupid mechanical failure? It still was not the mission that they really wanted, with the loss of the main antenna.

How nervous will the James Webb team be after a successful launch, and now they get to see if their mirror unfolds correctly?

Send up the stuff that can't be built in space. At first, you are only going to be building the basic frame out of in situ resources and slapping on the parts that were launched up. Then, as you develop capabilities, more and more of the satellite is sourced from resources that did not need to be launched from earth, until the only thing that is coming up is electronics and optics and other high end products that require larger supply chains. Even if you can't build high end electronics in space for quite a while, making simpler control chips is something that can be done in a basic university EE lab, and so should have little difficulty transferring to space.
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Also, we have to consider the economic impact of the coming generation of reusable rockets. If Starship delivers on even most of its promise, We will eventually be at the point where the mass of a satellite and its launch cost will be a small fraction of what they are now.



Not even remotely true, except for a small subclass of near Earth asteroids.

Let's assume Ceres, or a similar asteroid in the asteroid belt.

It takes about 11.8 km/s of Delta V to get from the surface of the Earth to Geostationary Transfer Orbit. You have to do that for both the Moon and Ceres. For the Moon, you then need to get into lunar capture, circularize and drop into LEO, then down to the surface. All of that takes about another 3.2 km/s, or 5.7 km/s from LEO.

For Ceres, you have to get to Earth Escape, then trans-Ceres injection, then when you get there you have to get into a capture orbit, then down to LCO. Here's a NASA page showing the total Delta-V for Ceres from Low Earth Orbit: Hohmann Transfer to Ceres by Launch Window. You can see that the Delta-V is between 9 and 10 km/s. And the travel time is typically over three years. There's a reason why NASA uses complex gravity-assist trajectories to get to the outer planets and asteroids. Because it takes a lot of energy to get there, even in a Hohmann transfer orbit. Almost twice as much as to land on the Moon.

So to get to Ceres, you need more Delta-V than getting to the surface of the Moon, and it takes three years instead of three days. So equivalent resources on the moon could be harvested and delivered to LEO cheaper than they could from Ceres.
What I am talking about here is specifically asteroid to asteroid travel. The whole part of your equations involving breaking out of gravity wells does not apply, as that is the entire point of staying away from gravity wells.

Do your math on Ceres to Vesta, and see if it's that expensive.
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Now, there are a handful of Near Earth Asteroids that are closer in terms of Delta-V. But they are all quite small and we have no idea if there is anything valuable there. All the rest of them are a LONG way away, and require huge amounts of energy to get there and back. Even more so than Mars, because at Mars you can use aerobraking. At an asteroid, not so much.
Well, we check out the ones that are easiest to get to first, then use the resources and technology that we develop to get out to further ones. Delta-V is far less important if you don't have to lift your fuel out of a gravity well. No matter what the NEA's are made of, we can turn it into fuel. It is guaranteed to have a decent amount of oxygen in it, and so we split that oxygen out, and then just recombine it with what we separated it from, if nothing else. Probably the best would be aluminum, as that is likely to be very common, and it is easy to make a simple rocket out of. If you didn't lift it out of a gravity well, it's practically free. We don't have to restrict ourselves to the lowest energy orbits if we don't want to.

Once you have things established, you can slap a little rocket pack on a big pile of semi-processed ore, and it doesn't matter if it takes a decade or more to work its way to its destination. People and valuable goods may want a shorter trip, though.
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And when doing economics, that 3.5 year travel time is pretty daunting. Any money invested in the hardware is going to require seven years from launch at minimum to get anything back. Tying up a billion dollars for a decade would probably incur more in carrying costs than the entire fuel cost of flying to the moon, landing, and coming back.
It takes that long to build any of our giant industrial machines right now, at about the same cost. Planes, cargo and oil ships, oil drilling platforms, power plants; these all take years and decades before they are available to start returning on investment.

Now, you can argue that those all have guaranteed returns on investment, unlike asteroid prospecting, but then, I'd remind you that the airline industry as a whole is out over a billion dollars over a faulty sensor on a couple 737 MAXs. Deepwater Horizon should have cost BP far more than it did, but it still lost a couple asteroid probes worth of money in damages and cleanup.

These are not daunting numbers in terms of cost or time on return. What is daunting is the unknown parts of the risk. There are too many unknowns involved for the underwriters to okay such an undertaking in any publicly traded company. SpaceX is getting away with some pretty risky bets that would not be allowed by shareholders, and ultimately, I think that they will end up losing one of them, but hopefully not until they've gotten far enough to show others the way.

That's why the govt really needs to do more of the deep space stuff while allowing private industry to take over the areas that have already been well developed. It needs to be the first mouse so the second gets the cheese.
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Eventually, I imagine we could see facilities out there that never come back, but just keep sending back regular amounts of cargo. At that point, it might make sense. But until we are at the point of operational mining, just exploration and learning through iteration will take decades when every round-trip takes seven years or more.
My point is that we should be working towards operational mining. We won't just get there without pushing to get there.
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Again, a lot of this stuff (and the O'Neill cylinders) were considered before the Moon because our view of the Moon post-Apollo was that it was a dry, dusty rock with nothing of interest and where everything people need would have to be imported. That's no longer our view of the moon. We are increasingly seeing it as a relatively wet world with all sorts of potential resources. The existence of extensive water changes the entire game when it comes to the exploitation of the Moon. But it takes a long time for new data to make its way into the zeitgeist of an entire industry, so most people still dismiss the moon as uninteresting.
The moon is not useless, but it is in a gravity well, and gravity wells are for suckers.

There is science to be had on the moon. Just from what we brought back with Apollo, we learned quite a bit about the Earth. If we could drill down hundreds of feet, or explore lava tubes, or whatever the lunologists can come up with. It could also be used as a launcher for deep space probes. It has enough mass that it's not going to notice when you use accelerators to fire something out at greater than solar escape velocity. Maybe a giant radio telescope on the far side, where it is shielded from the EM pollution of the Earth.

There may be resources on the moon. I don't know about using the water for fuel, that seems wasteful, it is going to be a limited resource, and if you are planning on colonizing the moon at some point, you may want to keep it around. Helium 3? Sure, show me a fusion reactor that can use it though. That's farther off, IMHO, than full scale space manufacturing. What else does the moon have that asteroids do not?

Not saying we shouldn't visit the moon, and maybe even set up shop there to some extent. But when it comes to colonization, actually creating settlements to grow and become largely independent, the asteroids is where it's at.

Last edited by k9bfriender; 08-09-2019 at 06:45 PM.
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