http://www.bbc.co.uk/news/science-environment-17827347

Details have been emerging of the plan by billionaire entrepreneurs to mine asteroids for their resources.

The multi-million-dollar plan would use robotic spacecraft to squeeze chemical components of fuel and minerals such as platinum and gold out of the rocks.

The founders include film director and explorer James Cameron as well as Google's chief executive Larry Page and its executive chairman Eric Schmidt.

They even aim to create a fuel depot in space by 2020.

However, several scientists have responded with scepticism, calling the plan daring, difficult and highly expensive.

So, a group of very rich men have decided to have a go at mining near earth asteroids. It seems incredibly ambitious, but also, crucially, it has a lot of money behind it.

What do you think? Is this a good idea? Is it even feasible at the moment?

Personally I hope this gets off the ground, quite a few people here have said that private industry should lead the way in space exploration and this seems to be the biggest example of this yet. I am however personally rather sceptical at the moment, several other members here have said that the technology and expertise required is simply to expensive for private companies to fund and hope to turn a profit.
I have read that a similar plan by NASA to land on an asteroid and bring back a small amount of it was going to cost near a billion dollars, this venture plans to (eventually) bring back much more material for much less money.

"I remember when Google Industries used to be just a search engine back in the day."

Is this a good idea?

Of course. More information about near-earth asteroids in short term and lower prices for those rare metals in long term are both things that'll greatly benefit us. In addition, they plan to greatly reduce costs for future space exploration by allowing ships to refuel in space (their first priority is asteroids that contain a lot of water to convert that into fuel).

Is it even feasible at the moment?

They said in the pressconference that the company is already cashflow positive (they have been researching, working and building for 3 years now) through contracts with other companies. Apprantly has something to do with promising to let other companies hire their telescopes and selling technologies.

Either way, I don't get the impression the investors only care for the money here. The appeal of investing in space exploration is quite strong by itself, even without the potentially (but unlikely) huge profits.


I have read that a similar plan by NASA to land on an asteroid and bring back a small amount of it was going to cost near a billion dollars

They did a pretty great job explaining in the press conference that their way of working isn't like the way NASA does it currently. Not similar at all, apparantly.

By the way, the company google doesn't have anything to do with this (yet). While it's true that the investors Larry Page and Eric Schmidt of this project also happen to work at Google, they invested only their own money.

Hey, if it works out, good! If it doesn't, well at least we will learn something from the experience.

In addition, they plan to greatly reduce costs for future space exploration by allowing ships to refuel in space (their first priority is asteroids that contain a lot of water to convert that into fuel).

How do they turn the water into fuel? Surly they could not do it in any realistic way with solar power on an astorid?

How do they turn the water into fuel? Surly they could not do it in any realistic way with solar power on an astorid?

Perhaps attach a solar plant on the asteroid and separate the oxygen from hydrogen with low level electrolysis?

Someone will run the numbers again and conclude that's a prestige project and a very expensive hobby.
I'd be surprised if this goes anywhere.

X-posted from the space thread:

This was brought up on #nes earlier today, and as we discussed it I pointed out some problems that the scientists agreed with. Specifically:

However, several scientists have responded with scepticism, calling the plan daring, difficult and highly expensive.

They struggle to see how it could be cost-effective, even with platinum and gold worth nearly £35 per gram ($1,600 an ounce). An upcoming Nasa mission to return just 60g (two ounces) of material from an asteroid to Earth will cost about $1bn.

But I must admit that if billionaires want to blow billions on an investment that won't be realized for decades - and I mean decades - then I guess government intervention isn't all that necessary (on a fundamental level, anyway, as NASA advisers are certainly involved in the project). Once the ball gets rolling, there will be a certain inertial effect that even a zomg-communist like myself must admit is conducive to progress.

In my opinion, it'll just be a lot slower. But it'll happen. So long as the involved parties are happy with being in the red for as many as 20 to 30 years.

This is not economically feasible now. But someday likely will be. The point of mining asteroids is not to bring metals to Earth, but to make metals available for construction in space. And that's a long ways off. Still, we have to develop the tech at some point. And there may be spinoffs from the tech development that pay the bills. In the meantime, it's all just speculation. And high risk at that.

I'd say it's technically possible, but they're decades from seeing a profit I'd think. Though it will eventually be a lucrative industry, and I suppose there's something to being the first ones capable of doing it. Plus, space robots.

In tomorrow's news: Richard Branson announces he's funding development of an interstellar warp drive. Plans are "vague" but expect completion some time in 2067.

I should hope not. If he builds an Alcubierre drive he'll likely kill us all.

Totally awesome. The awesomeness has its own value beyond the economic values of the materials mined and the technologies developed, which, yeah, will probably take a long time to realize. We need stuff like this to get excited about and inspired by.

How do they turn the water into fuel? Surly they could not do it in any realistic way with solar power on an astorid?

Perhaps attach a solar plant on the asteroid and separate the oxygen from hydrogen with low level electrolysis?

A better question is how they want to store hydrogen in space for years. Because, you know, hydrogen boils off very quickly. It's nearly impossible now to store it effectively for a period longer than days.

This probably can be solved by hi-tech development, but it will take time and money.

Someone will run the numbers again and conclude that's a prestige project and a very expensive hobby.
I'd be surprised if this goes anywhere.

I am willing to be positively surprised, while remaining the sceptic I am.

But I must admit that if billionaires want to blow billions on an investment that won't be realized for decades - and I mean decades - then I guess government intervention isn't all that necessary (on a fundamental level, anyway, as NASA advisers are certainly involved in the project). Once the ball gets rolling, there will be a certain inertial effect that even a zomg-communist like myself must admit is conducive to progress.

In my opinion, it'll just be a lot slower. But it'll happen. So long as the involved parties are happy with being in the red for as many as 20 to 30 years.

I think the comparison with the NASA sample-return mission is idiotic. It's like comparing the per-gram cost of obtaining a geologic sample during an initial survey of a previously inaccessible location here on Earth with the per-gram cost of commercial industrial mining elsewhere.

I remain sceptical though that mining asteroids for substances to be used on Earth will get anywhere. Mining water for propellant to be used in space is far more promising. Most of all, I am glad that people with money want to pour it into something that can actually help humanity as a whole, instead of buying some island in the Pacific along with their personal harem or something.

I'd say it's technically possible, but they're decades from seeing a profit I'd think. Though it will eventually be a lucrative industry, and I suppose there's something to being the first ones capable of doing it. Plus, space robots.

You can go only so far with robots. Any large-scale mining operation in space would require some human presence.

I remain sceptical though that mining asteroids for substances to be used on Earth will get anywhere. Mining water for propellant to be used in space is far more promising.

They probably agree with you. After all, they're searching for carbon-rich asteroids right now, not platinum rich asteroids. Not only so they use the water within to fund eventual actual mineral mining, but also because other space companies would gladly pay a lot of cash to buy water from them in space.

Still, once that's done, they'll search for asteroids to mine.

You can go only so far with robots. Any large-scale mining operation in space would require some human presence.

Press release Q&A: no humans will be involved because they're just too expensive.

Either way, another big misunderstanding that I want to clarify: they don't have to wait till the first minerals come back to earth before they get their first return on investment. At all. Renting their telescopes and selling materials, fuel and technologies to other space companies should keep the company profitable enough until the actual mining of platinum part starts.

Lastly, their plans aren't vague. For example, they promised to start launching spacecraft within 24 months.

They probably agree with you. After all, they're searching for carbon-rich asteroids right now, not platinum rich asteroids. Not only so they use the water within to fund eventual actual mineral mining, but also because other space companies would gladly pay a lot of cash to buy water from them in space.

Still, once that's done, they'll search for asteroids to mine.

They could probably mine water, bring it to LEO (aerocapture/aerobraking FTW), and electrolyse it there according to demand. Storing water is several orders of magnitude easier than storing hydrogen.

The question then is, why asteroids? The Moon is much closer, the delta-V requirements are basically the same, and we know there is water on the south pole. Even better, with a decent electromagnetic catapult, a steady supply of lunar water could be brought to LEO.

Press release Q&A: no humans will be involved because they're just too expensive.

Of course, but that's true now. I said it before, but for the sake of this thread I'll do it again - you can get only so far with a purely automatic system. The more complex the automatic system is, the harder it becomes to keep it operational.

Robots are used now in space exploration because of financial restrictions. A decent human-mission to Mars would return more data about the planet than all the previous (surface) robotic missions combined.

If we are to build truly large-scale mining/manufacturing infrastructure in space, then the complexity itself will create the need for permanent human presence. It is impossible to make such a large automatic system to be fully self-maintaining simply because you'd have to plan for every possible malfunction that could occur and devise a fully automatic counter-measure. At some point, this will increase the cost and mass of the system far beyond the requirements of a few humans to watch over the facility.

But yeah, I am talking about distant future here - a future in which there actually is some industry in space.

Either way, another big misunderstanding that I want to clarify: they don't have to wait till the first minerals come back to earth before they get their first return on investment. At all. Renting their telescopes and selling materials, fuel and technologies to other space companies should keep the company profitable enough until the actual mining of platinum part starts.

I understand that. It's a clever way of maintaining space business while it works. The problem is that it could very easily fail - I hope that the people behind it are willing to step in if this were to occur and fill the hole in the cash flow with their own money.

Lastly, their plans aren't vague. For example, they promised to start launching spacecraft within 24 months.

We'll see. (My usual response to any space plan - they have a way of never getting anywhere ;) ).

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To those who think I am too pessimistic - I am not. I strongly believe that we're at the beginning of our space age. The Cold War space race and the lethargy that followed it were the Prologue, a foreshadowing of the real space age that will be driven primarily by economics, individual ambition, and dreams of many. The governments' influence on what we do in space will decrease in time - I just hope that they will choose to actively support this new space age rather than to hinder it with stupid regulations. ("nono, you can't go to space, because it is dangerous" :scared: )

A decent human-mission to Mars would return more data about the planet than all the previous (surface) robotic missions combined.

Why (or how) is that so?

Why (or how) is that so?

Because our robots are extremely limited machines designed to perform specific tasks which are pre-determined here on Earth. Humans on the other hand are multi-purpose, independent self-aware machines that, despite their propensity for occasional malfunctions due to emotional issues, can alter their mission parameters in accordance to new circumstances. In other words, if a human being sees something interesting, it can go and investigate. Robot can't do that if it hasn't been designed for it.

Our robotic rovers are exceptional machines, let there be no doubt about that. But they don't even approach the capability a single human being would deliver in their place. The entire years-long mission of the rovers could be covered by a human in the span of a week, perhaps less - and probably better. Give that person the right tool kit and he or she will outperform dozens of robots.

Let me quote the greatest Mars-nut on Earth:
Robotic probes can help out in such a search – and should be aggressively pursued – but by themselves are completely insufficient. Fossil hunting requires the ability to travel long distances through unimproved terrain, to climb steep slopes, to do heavy work and delicate work, and to exercise very subtle forms of perception and on-the-spot intuition. Astrobiological investigations require the ability to drill, sample, culture and study life drawn from Martian groundwater. All of these skills are far beyond the abilities of robotic rovers. Field paleontology and astrobiology require human explorers, real live scientists on the scene.

I'm seeing some pessimism on various sites saying that the value of rare-earths and other mined resources would crash if they actually pull this off. Can anyone explain why they couldn't just control the price if they are the only ones in space doing it? Like some sort of Space OPEC.

I'm seeing some pessimism on various sites saying that the value of rare-earths and other mined resources would crash if they actually pull this off. Can anyone explain why they couldn't just control the price if they are the only ones in space doing it? Like some sort of Space OPEC.

That's nonsense. In order for the prices to crash, they would have to start bringing huge amounts of these metals to Earth now. That's not what will happen.

What could happen is that in the future, the demand for these substances will increase and so will their price. This in turn will provide further economic incentive to get the stuff from space.

I'm seeing some pessimism on various sites saying that the value of rare-earths and other mined resources would crash if they actually pull this off.

One of the people behind this (can't remember who) said that if the prices crash, they did their job well. In fact, Peter Diamandis his "why we do this" talk at the start of the press conference was all about how they want to make those resources abundant. Besides, if/when they're so succesful that they have the ability to lower the prices of those rare-earths, they'll quickly lose their monopoly as others try to mimic their succes. That said, I'm not sure why you call that prospect of crashing prices something to be pessimistic about.

But as Winner said, even if this whole thing turns out to be profitable, it'd still take a long time before the prices change here.

You can go only so far with robots. Any large-scale mining operation in space would require some human presence.

Obviously, but that's far too much risk for any private company to assume right now.

if they can mine asteroid. whats stopping them for hurling them to earth ? :p

if they can mine asteroid. whats stopping them for hurling them to earth ? :p

The laws of nature? :p

It's not impossible, but the amount of energy to profoundly alter the solar orbit of even a relatively small asteroid (hundreds of metres in diameter) is way beyond what we can do right now. We'd have a problem deflecting such rock if it was headed our way, and that would be a much smaller change in trajectory.

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BTW, notice that this company wants to focus on NEOs, that is asteroids whose orbits are close to Earth's orbits. Delta-v requirements to reach them are much lower than the asteroids in the Main Belt (you need more energy to reach them than to go to Mars). Some of these objects are probably dead comets, so theoretically they should still contain volatiles.

The laws of nature? :p

It's not impossible, but the amount of energy to profoundly alter the solar orbit of even a relatively small asteroid (hundreds of metres in diameter) is way beyond what we can do right now. We'd have a problem deflecting such rock if it was headed our way, and that would be a much smaller change in trajectory.

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BTW, notice that this company wants to focus on NEOs, that is asteroids whose orbits are close to Earth's orbits. Delta-v requirements to reach them are much lower than the asteroids in the Main Belt (you need more energy to reach them than to go to Mars). Some of these objects are probably dead comets, so theoretically they should still contain volatiles.

but it only takes a constant acceleration to alter its orbit and then, earth gravity will takes over. :goodjob:

but it only takes a constant acceleration to alter its orbit and then, earth gravity will takes over. :goodjob:

What? :confused:

NEOs are on their orbits around the Sun. They will remain there unless you could first alter their orbit to bring them close to Earth, and then slow them down enough for them to be captured by Earth's gravity.

If you do the math, you'll find out that it would take HUGE amounts of fuel to capture even a relatively small asteroid. The best we could do with present-day technology is to capture a rock a few metres in diameter, and even that would be a challenge. Of course, such a rock wouldn't do much damage if you wanted to use it as a weapon. You'd be better off just to launch a mass of depleted uranium-tungsten to low Earth orbit and then use it to hit targets anywhere on the planet. That would be a nice first strike weapon.

I am skeptical, but hey, I'm not going to object to rich people blowing their money on scientific R&D. Regardless of what happens, we'll get something good out of it, even if its applications aren't readily apparent.

What? :confused:

NEOs are on their orbits around the Sun. They will remain there unless you could first alter their orbit to bring them close to Earth, and then slow them down enough for them to be captured by Earth's gravity.

If you do the math, you'll find out that it would take HUGE amounts of fuel to capture even a relatively small asteroid. The best we could do with present-day technology is to capture a rock a few metres in diameter, and even that would be a challenge. Of course, such a rock wouldn't do much damage if you wanted to use it as a weapon. You'd be better off just to launch a mass of depleted uranium-tungsten to low Earth orbit and then use it to hit targets anywhere on the planet. That would be a nice first strike weapon.

ah yes, building an armed asteroid :D

thats a great idea too.

Someone will run the numbers again and conclude that's a prestige project and a very expensive hobby.
I'd be surprised if this goes anywhere.

It's got a huge startup investment cost, which these guys have (they're billionaires, etc.), but also an incredible ROI potential, if they manage to find an asteroid rich in rare minerals and a way to get all that stuff back to Earth at a decent cost.. which I'm assuming they have ideas for.

I doubt it'll happen anytime soon myself, but it'll happen eventually.

It is interesting that the planet is now wealthy enough that some people can (maybe seriously) even consider doing this. What I like is not the ROI, but the fact that it is baby-steps in shifting part of our economy into space. It strikes me that the long-term externalities can be positive in a way that direct profits might never be.

It is interesting that the planet is now wealthy enough that some people can (maybe seriously) even consider doing this. What I like is not the ROI, but the fact that it is baby-steps in shifting part of our economy into space. It strikes me that the long-term externalities can be positive in a way that direct profits might never be.

I don't understand what you you mean by the first sentence. Earth's GDP is definitely sufficient to support a space colonization effort 1000 times the size of what we're doing in space now. Availability of money has never been an issue.

The people behind this particular project claim that the change they appreciate the most is the "miniaturisation" of space, the fact that even relatively small subjects can afford to do things in space that only large nation state governments could possible be able to organise and fund before.

Yes, but clearly it's not something that's seriously democratically desired. So, planetary or country GDP just doesn't seem to be a real factor. To do this, you currently need wealthy fanbois, who're in charge of their own money. We're now at the stage where those fanbois can consider doing this. Compare to a decade ago, where the super-rich were just buying trips to the Int'l Space Station.

About the altering an asteroid's path thingy, here's a relevant TED talk (first ârt talks about how scary meteor impacts are, second part is about changing the course of asteroids).

http://www.ted.com/talks/phil_plait_how_to_defend_earth_from_asteroids.html

Compare to a decade ago, where the super-rich were just buying trips to the Int'l Space Station.

Some random trivia: the founders of Planetary Resources are also responsible for selling trips to the Int'l space station to the super-rich. As such, the super-rich buying those trips helped funding this asteroid mining company.

I think the comparison with the NASA sample-return mission is idiotic. It's like comparing the per-gram cost of obtaining a geologic sample during an initial survey of a previously inaccessible location here on Earth with the per-gram cost of commercial industrial mining elsewhere.

:huh: No it isn't. It's like comparing the cost of going into the Marianas trench to the cost of going into the Marianas trench at a different point. Avenue of approach, plan of attack, required technology and overhead are going to be pretty similar. Same with space. Now then, if you're talking about making space more accessible and then mining it, you'd be right - but establishing that infrastructure is essentially a separate issue insomuch as it, by itself, is unprofitable.

There's a reason that the US government subsidized the transcontinental railway. It was an expensive endeavor, and not guaranteed to turn a profit by itself, but would improve other industry by virtue of its utility.

I remain sceptical though that mining asteroids for substances to be used on Earth will get anywhere. Mining water for propellant to be used in space is far more promising. Most of all, I am glad that people with money want to pour it into something that can actually help humanity as a whole, instead of buying some island in the Pacific along with their personal harem or something.

Actually, mining virtually any asteroid could be profitable (many have some type of semi-valuable mineral, and all would be purchased by research labs for teh science), so long as most of the space infrastructure is developed ahead of time. Once you have that set up, everything else follows. It's like having a coal mine in some distant location - it's nearly impossible to benefit from the coal mine right here and right now unless you have a means of quick and easy transport, such as a railway. Establishing the rail line is going to be expensive off the bat, but creates the infrastructure that improves the efficacy of the industry it serves.

You can go only so far with robots. Any large-scale mining operation in space would require some human presence.

Not necessarily. UAV technology is advancing at an alarming rate, to the point that pilots will, eventually, no longer be necessary in situ. Same basic principle applies to spacecraft.

I am very skeptical.
I doubt that it is technologically possible within the next 25 years and I also think the Chinese would flood the market with the expensive rare earth elements to ruin the prizes (and raise them again after that) before anyone is able to break the monopoly. It's a bit like the De Beer diamond monopoly in the 20th century.

For the technical aspect I will completely ignore all issues of finding resource rich asteroids and bringing them back to an Earth orbit.
To make any metal available on earth you would have to provide some kind of heat shielding for the reentry

For the supply of the ISS there are/have been four different transport systems with different prizes for payload earth->orbit
Progress: 13.2 million €/ton (Russia)
ATV: 43.4 million €/ton (EU)
HTV: 33.3 million €/ton (Japan)
Space Shuttle with MPLM: 34.3 million €/ton (USA)

Even if you should be able to reduce the cheapest prize for surface->orbit transit (Progrss) by 25% it would still be ~9.24 million €/ton.
So one of the big questions (after bringing the Asteroids to an Earth orbit) would be how large the weight ratio of payload/heat shielding would be.
Obviously it would be necessary to reduce the amount of material which has to be brought to the surface. To achieve this orbital processing of ore might be necessary which would require some kind of orbital refinery which has also to be brought into orbit.
I can't imagine this would be feasible in any way.

A way to help make this venture more profitable would be to enact stricter environmental protection laws here on Earth making the mining of these elements more expensive down here. I doubt it would ever raise the price enough on it's own, but every little helps.

Like everyone I have my doubts about this thing, but I do have the impression you are all too pessimistic. Plus, there's quite a bit of misunderstandings here, so allow me to clarify some stuff:

I also think the Chinese would flood the market with the expensive rare earth elements to ruin the prizes (and raise them again after that) before anyone is able to break the monopoly.

Not feasible for the Chinese at all, as they don't have any mines (and hence no stash worth considering) for those rare-earths metals Planetary Resources wants to mine. The Chinese also have no reason to stop the asteroid mining (on the contrary, it'll help them a lot).

The russians on the other would have a reason to try as they're by far the most important producer of some of those rare-earths currently. However, despite the fact that Russia is going to sell it's whole reserve of palladium over the next 3 years, the price of that metal is prognosed to increase. Them selling it certainly will have an impact, but despite having by far the biggest reserve of the metal around they still won't "ruin" the prices. In other words, they wouldn't even be capable of ruining the price if they wanted to as the production from mining is pretty much capped. If they can't, nobody can. Idem ditto for other resources.

To make any metal available on earth you would have to provide some kind of heat shielding for the reentry

Heat shielding is needed for reentry of spacecraft (like space shuttles) because the contents can't handle the high temperatures. However, platinum and other metals don't really suffer from those high temperatures at all. As such, a layer of iron around whatever metal they want transported back to earth would work just fine. It also happens that the platinum found in those asteroids will have plenty of iron around it, so you really don't need to launch heat shielding into space at all. Don't get me wrong, there are plenty of problems with getting the platinum (or those other rare-earths) back to earth, it just happens heat shielding isn't one of them.

Either way, the real question is wether them mining water will be worthwhile. It's much more important, because it's what they'll do first and if mining water turns out to be infeasible, mining for metal will never work out. Prices of those metals on earth doesn't really matter so much. The price of water in space is what matters.

Some random trivia: the founders of Planetary Resources are also responsible for selling trips to the Int'l space station to the super-rich. As such, the super-rich buying those trips helped funding this asteroid mining company.

Oh, certainly. There was a sense of momentum even back then.

Yes, but clearly it's not something that's seriously democratically desired. So, planetary or country GDP just doesn't seem to be a real factor. To do this, you currently need wealthy fanbois, who're in charge of their own money. We're now at the stage where those fanbois can consider doing this. Compare to a decade ago, where the super-rich were just buying trips to the Int'l Space Station.
Well, I live in a (still) democratic country, and I have desired this for DECADES. :huh:

Anybody asked Oprah Winfrey to invest? Isn't she the richest woman in the U.S.?

Individual fortunes aren't going to get it done in the foreseeable future. For it to be practical, the rock needs to be moved to someplace in Earth orbit. And we only have theory for doing that so far. This is going to remain highly speculative for a good deal longer a time.

For it to be practical, the rock needs to be moved to someplace in Earth orbit.

Why would you want to move the whole asteroid near Earth's orbit? You would spend a huge amount of effort moving what is mostly useless rock. It would be much more efficient to extract the desired substances at whatever place the asteroid is and just haul that back to Earth.

Unless you want to crash land the asteroid on Earth, you need to put the extraction machinery into space anyway. And it should be much more efficient to move that, than to move a million tons of rock.

I suspect it would either be cheaper to fling the 'good stuff' towards Earth, or the 'bad stuff' away from Earth to push the asteroid closer.

Why would you want to move the whole asteroid near Earth's orbit? You would spend a huge amount of effort moving what is mostly useless rock. It would be much more efficient to extract the desired substances at whatever place the asteroid is and just haul that back to Earth.

Unless you want to crash land the asteroid on Earth, you need to put the extraction machinery into space anyway. And it should be much more efficient to move that, than to move a million tons of rock.


The reason to move it is to make all the resources of it available. If you were to mine in in place, you would need to not only get the machinery into orbit, but also way out to the rock.

Here's my vision of it. You build a bunch of space robots that are cylinders with nuclear power plants. They go to the asteroid and place one end up against it. Then they use lasers to vaporize pieces of the asteroid, and ionize them and shoot them out of the other end to provide thrust. Slow, but you could eventually place the rock where you wanted it with a few dozen of these. Once you have it in place, all the remaining material of it could be used for whatever projects you have in mind. And most of the power once it is in Earth orbit can be solar.

But if you send the machines out to the rock, and then send the metals back, then you need to supply fuel coming and going. And you only get to use that small portion of metals that you can send back.

The reason to move it is to make all the resources of it available. If you were to mine in in place, you would need to not only get the machinery into orbit, but also way out to the rock.

That's hardly much of a problem. Don't forget, once you've achieved low Earth orbit, 90% of your worries are gone. Getting out of this deep gravity well is the single most difficult problem in spaceflight, the rest is relatively trivial in comparison.

Here's my vision of it. You build a bunch of space robots that are cylinders with nuclear power plants. They go to the asteroid and place one end up against it. Then they use lasers to vaporize pieces of the asteroid, and ionize them and shoot them out of the other end to provide thrust. Slow, but you could eventually place the rock where you wanted it with a few dozen of these. Once you have it in place, all the remaining material of it could be used for whatever projects you have in mind. And most of the power once it is in Earth orbit can be solar.

The energy to do that is simply too much. You don't want to move something that's 90% useless. It's easier to extract what you need on the spot, and then fling the useful stuff (water, platinum-group metals) to Earth.

What you described will probably be done much later, when we start moving icy asteroids from the outer Solar System to Mars (and explode them in its atmosphere to get heat, nitrogen, and water). Moving icy bodies makes sense because most of their mass is useful in one way or another.

But if you send the machines out to the rock, and then send the metals back, then you need to supply fuel coming and going. And you only get to use that small portion of metals that you can send back.

That's why you use in-situ resources to produce all the fuel you need to transport the extracted propellant/fuel to Earth.

That's why you use in-situ resources to produce all the fuel you need to transport the extracted propellant/fuel to Earth.

Yep. That's how we'll do Mars too, once we eventually decide to do it. The key to space exploration and exploitation is to stop hauling everything up from Earth, and learn to live off the land. Even if we draw resources from Mars (or Luna, but she doesn't have much of anything useful), it's still much more practical that drawing it from Earth.