Colonizing other planets

[tater]

1 hour ago, Buster Charlie said:

Someone asked why would people go?

I asked this, but if you read it, it was largely in the context of science. There is no planetary science that cannot be done more cost-effectively by robots. 

 

Quote

Why do people go to Alaska? 

Not to stereotype  but beyond the adventitious free spirit pioneer types, you seem to have a lot of people skipping on child support, warrants for their arrest,  and lots of drugs and alcoholism. Oh yeah government subsidies. 

So the down side is our mercury colony is not really affordable for fugitives from justice types.

Manned spaceflight is a stunt.

I'm all for it, but the reason for it is exactly "adventure." For the bulk of humanity, it's no more than a way to vicariously visit those places ourselves. Colonies are another matter altogether. People go places like Alaska for many reasons, but being dropped naked in Alaska is millions of times easier than being dropped every bit as equipped as Mark Watney on Mars. On earth, it's possible to live, just live, if you wish. Hunt for food, make a shelter. Live. Everything on a space colony must be paid for, which requires some economic driver. None are forthcoming.

Colonies can therefore either be built by someone willing to throw money away (not impossible), or at gunpoint (governments). I don;t see governmental space programs getting into the colony business. Missions? Sure. Bases for long term use? Sure. Colonies? No.

 

Edited February 22, 2016 by tater

[Buster Charlie]

4 minutes ago, tater said:

I asked this, but if you read it, it was largely in the context of science. There is no planetary science that cannot be done more cost-effectively by robots. 

 

Manned spaceflight is a stunt.

I'm all for it, but the reason for it is exactly "adventure." For the bulk of humanity, it's no more than a way to vicariously visit those places ourselves. Colonies are another matter altogether. People go places like Alaska for many reasons, but being dropped naked in Alaska is millions of times easier than being dropped every bit as equipped as Mark Watney on Mars. On earth, it's possible to live, just live, if you wish. Hunt for food, make a shelter. Live. Everything on a space colony must be paid for, which requires some economic driver. None are forthcoming.

Colonies can therefore either be built by someone willing to throw money away (not impossible), or at gunpoint (governments). I don;t see governmental space programs getting into the colony business. Missions? Sure. Bases for long term use? Sure. Colonies? No.

 

But what if the cost of living on a floating Venus base is less than the cost of child support?

 

In all seriousness, the reason why, or economical feasibility, is not required for a conversions on how it could be done, or what is the least worst option. 

[tater]

 

The question is which is best. If we stick entirely on topic, science is pretty much off the table since any science can be better done by robots than people. Best would need to either be which is technically best (easiest, or with the best final result), or which is economically best (a fantasy world where there s some economic reason, otherwise which is cheapest).

[Spaceception]

4 minutes ago, tater said:

science is pretty much off the table since any science can be better done by robots than people.

People can do it faster.

[tater]

32 minutes ago, Spaceception said:

People can do it faster.

This is not true over reasonable time frames, and not true at all when you look at mass/cost.

Take current telecontrol of Mars rovers. Absolutely, a human could drive a rover faster right there. But mars rovers have lasted many, many years. 2 proposed Mars missions have either s short duration stay, or over a year. In either case, the possible sample selection per unit time might be higher, but the duration is vastly shorter. On top of that, the human mission is allowed what, 900 tons to Mars orbit in the 1990s, down to 450-650 now? You need to demonstrate that robots could not do as much given the same ~500 TONS delivered to Mars to do the work. The robots win right now, and 10 years from now, they'll be considerably more capable than they are right now.

Samples? The manned mission must return the crew, plus samples. Robotic sample return given identical resources could life all the mass of samples, plus the mass used for crew and their life support requirements. You could send multiple rovers, as well, and collect samples from areas that vary for the same cost. Sure, the geologist can pick great rocks quickly, but he's limited to XXkm around the landing site, anyway. Given the same resources, you could pout a couple rovers in interesting, "safe" places, and land others in places you've not risk landing a crew (due to terrain).

Sorry, but science as a rationale is pretty much indefensible. If we're sending people, then by all means maximize the science, but we should not pretend that people would be more effective/efficient at delivering the data we need.

Edited February 22, 2016 by tater

[fredinno]

On February 21, 2016 at 3:14 AM, peadar1987 said:

Humans, or to a lesser extent, humans teleoperating robots without latency, are more adaptable, and can do science faster. That's pretty much the only advantage in terms of research, and Mercury isn't exactly going anywhere, so speed is not of the essence!

Yeah, but more speed to get the science means that we can start thinking of getting more science faster. That's why Europa Clipper benefis by going on the SLS.

23 hours ago, WestAir said:

 I'm going to have to stop you right there. A lunar colony also deals with a vacuum and radiation. Mars doesn't have air or adequate air pressure, so again your colony needs to be air tight. The difference between these and a massive modular space station is that the later requires less Dv to build, and because soil and terrain are not an issue, there are fewer engineering concerns. Its easier to build a colony in orbit than it is on a foreign moon or planet. Period. It's not as enticing or romantic to the human psyche, but it's a lot easier to do.

Also, to compare a "large modular space colony" with the ISS is like comparing the Apollo Lunar Module with a Lunar colony. Totally not the same, and you know it.

A lunar colony likely has less structural problems to deal with than building an O'neil colony....

The area with the most economic potential right now is the moon,  since it needs less Delta V and time. Overall potential probably goes to Mars for being so Earth-like, and having a relavitive abundance and  balance of resources.

[tater]

The issue with the moon as colony (I'm going to assume my definition that means people born and raised there, possibly never leaving during their lifetimes) is that it is very unclear if 1/6 g is adequate for humans. Currently we have 2 data points, 1g, and near 0g. Any assumptions made without establishing the long-term health effects (including embryology) of values below 1g are not really worth anything, they are guesses. This also applies to Mars, BTW.

 

Edited February 22, 2016 by tater

[LN400]

Just a few stray thoughts.

1. Colonies in our solar system would first and foremost be science labs and/or resource harvesting. A relatively low number of people living there for a specific purpose of running these installations. Science would be the most likely as distances in our solar system are so vast an efficient transportation of raw materials and goods would be very far from trivial. Scientific data can be transmittet in a matter of minutes or a few hours. Sending recources around by cargo ships would take several years, possibly decades from origin to destination.

To set up colonies meant as an expansion of human living space will at some point mean we will have to face the idea of transforming planets/moons. First, as of today that technology does not exist. Second, to transform a planet or moon to have say, plant life growing, would demand energy. We could perhaps imagine artificial light and heating (artifical suns, in a lack of better words) but that is to say the least, speculative sci-fi. Else, we will have to rely on the good old sun. That puts limits to how far away from the sun we could have a successful transformation.

Next. If we one day are going to see transformed planets or moons, we can pretty much write off the moons around Jupiter and Saturn, and possibly Uranus and Neptune as well. The radiation levels hitting those moons would make for a very short life for any colonist there.

Scientific colonies could be set up pretty much anywhere. Radiation and heat are two main issues but at least from Venus and outwards could perhaps be where we'd set them up.

Industrial outposts, to serve industry and commerce here on this planet, I would think the moon, Mars+moons and possibly the asteroid belt. Another queston entirely is, are there resources there that are so important we are going to pay the pretty hefty pricetags coming with any freighter?

2. Outside our solar system. That is the most promising in terms of "colonies" for human expansion. Howeveer, the distances are so vast we should not make any illusions there would be a central, governing system with colonies. Rather, it would be fully independent systems. Even calling HQ back on earth would take the signals decades, or hundreds of years, or thousands of years, just to get to HQ. Then, after bureaucracy has wasted 10 years on debating the response, an equal time to get the response back to the colony.

Edited February 22, 2016 by LN400

[fredinno]

9 hours ago, LN400 said:

Just a few stray thoughts.

1. Colonies in our solar system would first and foremost be science labs and/or resource harvesting. A relatively low number of people living there for a specific purpose of running these installations. Science would be the most likely as distances in our solar system are so vast an efficient transportation of raw materials and goods would be very far from trivial. Scientific data can be transmittet in a matter of minutes or a few hours. Sending recources around by cargo ships would take several years, possibly decades from origin to destination.

To set up colonies meant as an expansion of human living space will at some point mean we will have to face the idea of transforming planets/moons. First, as of today that technology does not exist. Second, to transform a planet or moon to have say, plant life growing, would demand energy. We could perhaps imagine artificial light and heating (artifical suns, in a lack of better words) but that is to say the least, speculative sci-fi. Else, we will have to rely on the good old sun. That puts limits to how far away from the sun we could have a successful transformation.

Next. If we one day are going to see transformed planets or moons, we can pretty much write off the moons around Jupiter and Saturn, and possibly Uranus and Neptune as well. The radiation levels hitting those moons would make for a very short life for any colonist there.

Scientific colonies could be set up pretty much anywhere. Radiation and heat are two main issues but at least from Venus and outwards could perhaps be where we'd set them up.

Industrial outposts, to serve industry and commerce here on this planet, I would think the moon, Mars+moons and possibly the asteroid belt. Another queston entirely is, are there resources there that are so important we are going to pay the pretty hefty pricetags coming with any freighter?

2. Outside our solar system. That is the most promising in terms of "colonies" for human expansion. Howeveer, the distances are so vast we should not make any illusions there would be a central, governing system with colonies. Rather, it would be fully independent systems. Even calling HQ back on earth would take the signals decades, or hundreds of years, or thousands of years, just to get to HQ. Then, after bureaucracy has wasted 10 years on debating the response, an equal time to get the response back to the colony.

No, radiation levels are only bad in the innermost moons. Outer ones, like Titan and even Ganymede, are outside the radation belts.

[LN400]

1 hour ago, fredinno said:

No, radiation levels are only bad in the innermost moons. Outer ones, like Titan and even Ganymede, are outside the radation belts.

I stand corrected there then.

[Hannu2]

On 22.2.2016 at 11:33 PM, LN400 said:

Industrial outposts, to serve industry and commerce here on this planet, I would think the moon, Mars+moons and possibly the asteroid belt. Another queston entirely is, are there resources there that are so important we are going to pay the pretty hefty pricetags coming with any freighter?

Yes, there are some elements which are rare on Earth's crust and their limited availability and high price limits industrial applications. For example platinum group metals, which are used as catalysts in chemical and automotive industry and lanthanoid metals which have several uses in electric and optical industry (maybe powerful permanent magnets are the most important use). Most of these heavy elements in Earth have fallen to core soon after formation on the planet. There are much higher concentrations and practically unlimited amount of these elements in metal asteroids. It would need a huge investment before we can utilize these resources from space but unlimited supply and lower prices would finally give significant benefits and profits. It is not current yet but mining companies will certainly get interested in space mining when there will be significant reduction in launch prices (for example because re-usable stages) and commercial heavy launchers. I predict that severe development of mining machines may begin after couple of decades and first commercial mines begin to product after 50-100 years. I do not believe that human astronauts will get significant role as a workforce in that process and especially there will not be need for permanently manned colonies on asteroids.

[tater]

The economics of mining rare earths, etc, has got to be interesting, and I'd personally be interested in the take from an economist if there is an article out there to read. It seems like they are valuable entirely because they are rare. The cost to drag an asteroid to orbit with a huge supply might actually be small compared to terrestrial mining, at which point in order to keep the price up, they mining outfit would have to triple supply down, else they'd be doing something expensive (space mining) to collect a product that is cheap. It's an interesting balance.

Edited February 26, 2016 by tater

[fredinno]

13 hours ago, tater said:

The economics of mining rare earths, etc, has got to be interesting, and I'd personally be interested in the take from an economist if there is an article out there to read. It seems like they are valuable entirely because they are rare. The cost to drag an asteroid to orbit with a huge supply might actually be small compared to terrestrial mining, at which point in order to keep the price up, they mining outfit would have to triple supply down, else they'd be doing something expensive (space mining) to collect a product that is cheap. It's an interesting balance.

Yeah, the amount of fuel to bring anything of significant size to Earth Orbit pretty much makes it infeasible, without Orion Drives of course. But by then, we'll likely have lunar colonies, so no.

[tater]

You don't need much fuel at all, you just need time. You can herd a small asteroid, attach an ion drive to it, heck, a solar sail might be feasible. It just might take many years to get it to L@, or wherever is deemed safe. Even a small rock loaded with rare earths would be a windfall---at "rare" rare earth prices. Flood the market, and the price plummets. So the economics seem to be a long timeframe to get it, then you might have a lot to sell, but you need to sell in small units to maximize profit (sort of like DeBeers and diamonds. Diamonds only have value because the market is controlled, they are common, and should be cheap.

[fredinno]

23 minutes ago, tater said:

You don't need much fuel at all, you just need time. You can herd a small asteroid, attach an ion drive to it, heck, a solar sail might be feasible. It just might take many years to get it to L@, or wherever is deemed safe. Even a small rock loaded with rare earths would be a windfall---at "rare" rare earth prices. Flood the market, and the price plummets. So the economics seem to be a long timeframe to get it, then you might have a lot to sell, but you need to sell in small units to maximize profit (sort of like DeBeers and diamonds. Diamonds only have value because the market is controlled, they are common, and should be cheap.

Yeah, that is only going to work for so long- and by the time you can make solar sails large enough to slowly push a 1km M-type asteroid into High Lunar Orbit, you'll likely have multiple competitors, mining from asteroids in their native orbit, and from the moon.

[AngelLestat]

Well, I was spending some free time gathering and filling data related to potential colonization sites the best I could,  for sure there must be big errors there that I will request your help to improve the numbers with better estimations..  because there is no official data for many of those.

But looking info with this format is the only way to compare and understand the real difference between the locations.

Possible colonization sites - data

Vs Earth:	Gravity	Pressure	Temp (co)	Thermal Con	Solar Power	Radiation	Launch W	dV LEO to	dV back E.C.	Com. Delay
Mercury	0,38	0	-173 to 425	0,2	2000	350	90 days	17,2	13,5	4 to 12 min
Venus Clouds	0,87	0,7	20 to 60	0,9	600	10	584 days	3,8	10,4	2 to 14 min
Earth Cities	1	1	-20 to 45	1	240	1	-	-	-	-
Moon	0,16	0	-153 to 123	0,2	300	200	15 days	5,6	2,55	1,3 seg
Mars pole	0,38	0,006	-40 to -120	0,35	80	90	780 days	7,3	6,5	3 to 22 min
Mars low lat	0,38	0,006	15 to -80	0,3	180	125	780 days	7,3	6,3	2 to 22 min
Asteroid Belt	0	0	-120	0,2	180	250	460 days	10	7	18 to 38 min
Europa	0,13	0	-160	0,3	20	1000	400 days	13	13	33 to 53 min
Enceladus	0,01	0	-200	0,3	6	300	385 days	9	13	66 to 92 min
Titan	0,14	1,5	-180	1,4	7	10	385 days	7,3	11	66 to 92 min

 

This second table is not complete, these are all estimations based on data gathered, the first table try to measure all aspects with respect to earth, this is the same but from the cost perspective.
Before someone start with critics, it will be more helpful if collaborates with its own perspective on the numbers. Some numbers might seems with over precision taking into account that is only a rough estimation..  you should ask why?  I understand that it would be more correct to use bad, regular or good for those cases, but using numbers it help me to estimate other numbers based no others, in other words if I start with an estimation that it should cost 20 times more or less than earth for certain location.. then that value can help me based on general properties and other variables, to estimate values for other planet in base to comparisons.
(radiation is base on earth, which it has 2 smv per year, so if in the table you see 300, then it means around of 600 smv per year.)
.

Cost of:	Energy	h2o	CarbonF	Light E.	Heavy E.	Import from earth	Export to earth	Habitat
Mercury	0,5	70	10	50	0,2	2,7	0,6
Venus Clouds	0,4	50	0,08	0,5	0,1	1,3	1,3
SpaSta LEO	1	*	*	*	*	1	0,1
Moon	1,2	60	30	0,2	3	1,6	0,1
Mars Low Lat	3,2	25	0,3	0,5	4	2	0,4
Mars Poles	1,5	3	0,3	5	5	2	0,4
Asteroid Belt	2,5	10	10	2	0,05	2,3	0,9
Europa	0,9	4	15	7	15	3,5	0,8
Enceladus	0,8	2	20	10	20	3,5	1,2
Titan	0,7	7	1	0,2	5	3	3,5

 

Some examples of how I get some numbers:
Energy is base to solar, wind and nuclear... choosing the best case for each location.  Mercury is solar, PV films require extra care to work in space and at high temperatures, it needs extra radiators (no much), mercury is kinda tidally locked to the sun, so it only rotates around of 2 times over 3 turns arounds the sun, this mean extra storage for long periods or other complications (solar base power is also very complicated due low rotation speed)
Mars has 2 energy values, at low latitudes solar panels are a better option than nuclear, but it will cost more than 3 times than earth for the same power and for the same level of development (mars and earth).
Import and export values are based on different transport technologies, trying to figure out what should be the best case for each location (solar sails, mining ice asteroids close to orbit and using vasimr tugs, or using magnetic accelerators for those planets without much atmosphere, or using aerocapture, etc.

Before start to estimate a habitat cost, that should be related to energy cost, resources cost, import cost and the type of habitat calculating how much resources will needed for person (example:  for venus--> X kg of nitrogen, h2 and o2 to lift 700kg of weight allow it for each person + rooms + general sharing places, energy, etc..) so a estimation calculation base on "cost per person".

If someone wants to know the reasons behind some numbers,  just ask, also don't forget to provide your own estimation and reasons that might help to reduce errors on bad estimations or for reasons that I did not imagine..

[RocketSquid]

So, a few things. First of all, I kinda forgot I made this, but, looking at the responses, we seem to have a good discussion going on. I'll edit the poll to include Earth orbit and Solar orbit, unless that would delete the responses.

Second of all, what we need to make a space colony is one really determined, really rich guy. So we just need to hope that SpaceX works out. If it does, we may well have a mars colony soon™. Maybe.

[fredinno]

18 minutes ago, RocketSquid said:

Second of all, what we need to make a space colony is one really determined, really rich guy. So we just need to hope that SpaceX works out. If it does, we may well have a mars colony soon™. Maybe.

Actually, realistically, that would be a base. A colony needs to be self-sustaining, which cannot be done if it is not economically viable, which it is not (for the most part). I'd say eventually™.

[Nibb31]

4 hours ago, RocketSquid said:

Second of all, what we need to make a space colony is one really determined, really rich guy. 

I thought you said that you had read the thread? You need a lot more than that. There isn't one single rich guy who is rich enough for make a space colony, not even Musk. What you need is a business model that makes it worthwhile and sustainable, and nobody has invented that yet.

[RocketSquid]

8 hours ago, fredinno said:

Actually, realistically, that would be a base. A colony needs to be self-sustaining, which cannot be done if it is not economically viable, which it is not (for the most part). I'd say eventually™.

 

4 hours ago, Nibb31 said:

I thought you said that you had read the thread? You need a lot more than that. There isn't one single rich guy who is rich enough for make a space colony, not even Musk. What you need is a business model that makes it worthwhile and sustainable, and nobody has invented that yet.

I was exaggerating. What we really need is a base and an economic incentive to move there. A determined rich guy will help, but what needs to happen is something like this:

1. Base is created
2. Base needs crew beyond normal astronauts/workers, starts hiring civilians
3. Since base will likely remain understaffed, there will be a labor shortage, meaning that jobs there may have better pay.
4. Over time, the base would seek financial independence from earth. As a result, it would work towards sustainability.
5. If the base achieves a sufficient population, it has now become a colony. If not, it remains a base, but a more permanent one.

[Pipcard]

What do people here think is the ultimate goal of space exploration and space development?

If the prevailing attitude here is that space colonization and human spaceflight are pointless endeavors because "it will never be 'economic' (it really is the "dismal science") or rational" - that logic will be used to justify the abandonment of all forms of spaceflight except for the ones that are really pragmatic, like GPS and some geostationary comsats. Like someone will eventually say "what's the point of sending probes out there to study some 'worthless' rocks - there's no return on investment, it's more 'economic' to do almost nothing regarding spaceflight," making this the most anti-space "spaceflight enthusiast" community.

I know, I have some doubts about the practicality of space colonization too - but this prevalent defeatist attitude (e.g. a post basically saying that "we should never go to Mars in this century because it is too expensive" that was liked by over 20 people) isn't going to get us anywhere.

Edited March 26, 2016 by Pipcard

[fredinno]

8 hours ago, RocketSquid said:

 

I was exaggerating. What we really need is a base and an economic incentive to move there. A determined rich guy will help, but what needs to happen is something like this:

1. Base is created
2. Base needs crew beyond normal astronauts/workers, starts hiring civilians
3. Since base will likely remain understaffed, there will be a labor shortage, meaning that jobs there may have better pay.
4. Over time, the base would seek financial independence from earth. As a result, it would work towards sustainability.
5. If the base achieves a sufficient population, it has now become a colony. If not, it remains a base, but a more permanent one.

This is the optimistic scenario. Realistically, it'll be lucky if it ends up like this. Elon will likely be able to fund maybe a 10-20 man base (max) on Mars at the end of his lifetime- but will his successors continue to fund such a Mars Base when there is not profit to be made? Of course, the Mars Base itself would be beneficial to make Mars more viable, but my main concern is not really so much getting to Mars (though I am concerned about that too), it's staying there. Getting to Mars is comparatively easy.

[PB666]

7 hours ago, Pipcard said:

What do people here think is the ultimate goal of space exploration and space development?

If the prevailing attitude here is that space colonization and human spaceflight are pointless endeavors because "it will never be 'economic' (it really is the "dismal science") or rational" - that logic will be used to justify the abandonment of all forms of spaceflight except for the ones that are really pragmatic, like GPS and some geostationary comsats. Like someone will eventually say "what's the point of sending probes out there to study some 'worthless' rocks - there's no return on investment, it's more 'economic' to do almost nothing regarding spaceflight," making this the most anti-space "spaceflight enthusiast" community.

I know, I have some doubts about the practicality of space colonization too - but this prevalent defeatist attitude (e.g. a post basically saying that "we should never go to Mars in this century because it is too expensive" that was liked by over 20 people) isn't going to get us anywhere.

This is why we let NASA, ESA and RSA do the hard stuff, we can justify the cost businesswise, the businesswise cost of space is a future estimate, to get their you need seed organizations. Its like building the panama canal or intercoastal canal or an interstate freeway system. Once you have it in place then every business under the sun is attracted to it.

In physics this is know as the diffrence between kinetic and thermodynamic restrictions. Obviously thermodynamically under the right conditions making habitable places pays off because we have earth as an example, look how many businesses have chose to do business on earth (wierd as the example seems), but the kinetic and energy restrictions to building an earth are high. That does not mean that all restrictions are as high as building an earth, so it is the research into colonization that has to be done, and that were the G sponsered space programs come in. Science is not a profit industry, I keep being told this by the admins, the best science can do with industry and/or govt funding is break even, the net product is something that isn't sold by the researcher, makes a profit only for the publisher (basically for the chore of approving, editing and publishing). Therefore public funds ------>[Science: design, execute, evaluate]-----> Papers, trained and experienced engineers.

 

[Heimdall5008]

Also some notes from my side:

• I think many sub-dicussions here face a bit of a chicken or egg problem: e.g. Moon colony is easiest with current technology --> when we have Moon colony we have better technology --> therefore we do not need to build Moon colony --> then we have no reason to develop new technology
  The only possibility to prevent such a situation is a combined effort to establish the precursors as described by PB666 (great post, thanks).
• I think a space based industry is a requirement before we can think about colonies (as defined by the thread owner). And to get a space industry it has to be somewhere ecomonically sound. The best chance I see here is astroid mining for rare earths (especially when you consider that China has about 98% of the current production and the ROW (rest of world) would probably like to remove this dependancy). Sure this is a long term project but with the usage of the Interplanetary Transport Network you could realize a steady supply of materials with low cost to earth. Reentry to earth should also be handable. BUT...
• The first difficulty that we would have to solve is to get to Earth orbit to resonable costs (and ressources). We just do not have the ressources on Earth to handle a space industry with our current propulsion methods. We need either a very efficient SSTO or better a space elevator (with graphene at least theoretically possible :P)

So, to sum it up. I think many of the counter arguments in this thread come for a short term focus. It like we have just invented the first boats that can cross the Mediterrian Sea and discussing how we could establish a self sufficient colony in Antartica (yes, I know that we cannot do this today ;)).

[fredinno]

3 hours ago, Heimdall5008 said:

Also some notes from my side:

• I think many sub-dicussions here face a bit of a chicken or egg problem: e.g. Moon colony is easiest with current technology --> when we have Moon colony we have better technology --> therefore we do not need to build Moon colony --> then we have no reason to develop new technology
  The only possibility to prevent such a situation is a combined effort to establish the precursors as described by PB666 (great post, thanks).
• I think a space based industry is a requirement before we can think about colonies (as defined by the thread owner). And to get a space industry it has to be somewhere ecomonically sound. The best chance I see here is astroid mining for rare earths (especially when you consider that China has about 98% of the current production and the ROW (rest of world) would probably like to remove this dependancy). Sure this is a long term project but with the usage of the Interplanetary Transport Network you could realize a steady supply of materials with low cost to earth. Reentry to earth should also be handable. BUT...
• The first difficulty that we would have to solve is to get to Earth orbit to resonable costs (and ressources). We just do not have the ressources on Earth to handle a space industry with our current propulsion methods. We need either a very efficient SSTO or better a space elevator (with graphene at least theoretically possible :P)

So, to sum it up. I think many of the counter arguments in this thread come for a short term focus. It like we have just invented the first boats that can cross the Mediterrian Sea and discussing how we could establish a self sufficient colony in Antartica (yes, I know that we cannot do this today ;)).

As I understand it, the Interplanetary Transport Network depends on Lagrange points, which I am fairly certain does not work with asteroids. It also takes forever, and since time=money, you're much better off spending the extra Delta V on a Lunar mine than spending a year loitering in Heliocentric Orbit waiting for an asteroid intercept.

There are lots of other places to mine rare earths on Earth outside of China- the US had lots of mines before being out competed. Greenland is another example of a key mining zone. I think it will be a key kick-starter in Colonization- but mostly onto the oceans and Antarctica (And the Arctic, to a lesser extent) like Oil and Gas have done historically. If this will allow for long-term colonization is really up to question- after all, it's not economical to build greenhouses in Anchorage, even though food is expensive. Areas, in, say the Canadian Shield have a similar problem- the development of resources allows for only a short-term economic viability.

 

Granted, you can do things in space you can't on Earth...

Space elevators are not possible for at least the next century anyways.