I see that asteroid mining had already been extensively discussed in the context of today's technology (Ex. Is Asteroid Harvesting economic?) and the answer is a definitive "No" - it's not economical from Earth's perspective.

But what about the future? Assuming that a number of technologies would see a breakthrough, would it make sense one day to bring materials from space back to Earth? Let's presume that we have at least the following:

  1. Space elevator. Anything, including ISS-sized crafts can be lifted to geostationary orbit for a pure energy cost, and the energy can be effectively recouped when we lower the cargo down to Earth;

  2. Nuclear fusion. We can equip our space facilities with energy supply that is orders of magnitude higher than today and not depend on massive arrays of solar panels;

  3. Advanced robotics. All mining facilities and cargo ships can be operated by the AI;

Do you think it would make sense to mine the asteroids and bring the materials back to Earth in 100-200 years?

P.S. There are also some assumptions for this scenario:

  1. Nuclear transmutation is still not economically viable in this time period;

  2. Manufactured products are still in great (and growing) demand on Earth. We can either be bringing raw materials, or refine them in space, or build whole consumer products in space and lower them down, whatever is more economical.

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    $\begingroup$ I think it probably still won't be viable to bring materials to Earth - but, for building things in space, it might be a good option. Iirc Phobos has the lowest Delta-V requirements to LEO of all bodies that contain water in Solar System, for example $\endgroup$ – Mranderson Sep 26 at 18:37
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    $\begingroup$ Is this really a world building question or just some daydreaming? We don't know if and when it will become valid, technology is not a linear path like in a computer game. It might even be valid for a couple of years years and then not anymore like so many great breakthroughs in history were. Just go for it in your world. $\endgroup$ – Raditz_35 Sep 26 at 18:40
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    $\begingroup$ To piggy back on MrAnderson, the main benefit of mining astroids will be having materials in space already. Bringing those materials into smaller gravity wells such as the Moon and Mars will be more valuable than Earths. Manufacturing directly in microgravity environments would be even more valuable, but more difficult. $\endgroup$ – abestrange Sep 26 at 18:41
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    $\begingroup$ @Raditz_35 for the purpose of this question I assume that some of the technologies will be available at certain point in future. I also need to mention that I assume that nuclear transmutation would not be economical for the same time period. If you think that transmutation may be available before the 3 technologies that I mentioned, or any of those 3 technologies is non-realistic, you of course can argue for that. $\endgroup$ – Alexander Sep 26 at 18:45
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    $\begingroup$ You're asking us to predict the feasibility of technology 100-200 years in the future? Considering 99.9% of all human technology was created in just the last 150 years, that's a tall request. How will you judge the best answer? What do we know about economics 2 centuries from now? Are we dealing with the fact that all the asteroid material in Sol system is about a third or less the size of Luna? What do we know about the material needs in the future? What's valuable? Do we not have deep-core mining by then? This smells both too broad and very POB. $\endgroup$ – JBH Sep 26 at 21:32

Bring back to the Earth? Almost certainly not. As mentioned in the other related thread, anything you can find out there in the solar system you can also find right here on earth, and generally in vastly greater abundance and ease of retrieval, if you're comparing to the difficulties involved in getting to an asteroid and mining ore off it in a vacuum suit millions of miles from anywhere.

As MrAnderson mentioned in his comment though, the cost/benefit analysis changes dramatically as soon as you start getting lots of work being done in space, because if you can get your raw materials in space, you don't have to lift it out of a gravity well. If you can manufacture your spacecraft and assorted tools and equipment and what not in orbit, you don't have to lift THOSE out of a gravity well either, so orbital manufacturing and asteroid mining go hand-in-hand in support. So, the moment you need enough of something in space that it's cheaper to launch a factory into orbit to MAKE those things, rather than launch them from the surface individually, then it'll also start to be cost-effective to support those factories with asteroid mining.

  • $\begingroup$ Once it's cost effective to do mining and manufacturing in space without having to launch anything out of Earth's gravity well, couldn't it also be cost effective to ship it back to Earth by building something like a electromagnetic mass driver on the moon or a large enough asteroid? If you have completely automated, self-replicating mining and manufacturing, then the further cost once the first self-replicating unit was in place could be zero. $\endgroup$ – Hypnosifl Sep 26 at 19:35
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    $\begingroup$ @Hypnosifl Maybe, but I think it's more likely that at the point where it's cost effective to mine anything at all in space, any raw material you CAN mine is going to be more valuable in orbit than it is on Earth's surface. $\endgroup$ – Morris The Cat Sep 26 at 19:47
  • $\begingroup$ To rephrase my question - could space colonies one day become a net exporter of materials to the Earth? $\endgroup$ – Alexander Sep 26 at 20:13
  • $\begingroup$ The only case that it makes sense is to accumulate the really rare elements such as platinum group metals and iridium and occasionally export them to Earth en masse. You won't be exporting bulk Iron or nickel to Earth, but to other colonies and orbital ship yards. $\endgroup$ – abestrange Sep 26 at 20:37
  • $\begingroup$ But OP mentioned a space elevator already. Woudln't this drastically lower "launch" costs to an almost disregardeable amount? Or is it still a relevant energy cost? [Maybe the cost of opportunity because of limited capacity would be the deciding factor] $\endgroup$ – Hobbamok Sep 27 at 11:04

Definitely a good long term investment

Space is big. Insert H2G2 quote here. Moving around in space takes a lot of energy or a lot of time (as in, even more time than usual) if you're willing to use ridiculous witchcraft gravity assists to get that large amount of energy for free. Thus, with the perfect setup of planets, it'd be entirely possible to send automated ships to the asteroid belt with minimal amount of effort, and hopefully not moving too fast to waste energy slowing down when you get to the asteroid you want. Which is important, because you'd need it all for the return journey, as you have a lot of mass to ship back, which you will also use gravity assists. Getting your ship into space is free, since you specified that we've got an elevator to do so, and I've neglected to factor into account the cost for said elevator. Slowing the asteroids down sound tricky, but hopefully we can rendezvous a few boosters into it when it starts getting close.

The problem is that using gravity assists require waiting for the planets to align, and could take a long time, take a look at the Parker Solar Probe, for instance. So this would take a while. You could easily net a few billion dollars off an asteroid (until everyone starts doing it and the laws of supply and demand take over, anyway), you'll just need patience.

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    $\begingroup$ Consider the Interplanetary Transport Network. If you are willing to wait years for your goods to make their way across the solar system, transport can cost very little indeed. $\endgroup$ – Arkenstein XII Sep 26 at 20:05
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    $\begingroup$ Nitpick : you don't get energy for free in gravity assists, when you do a gravity assist from e.g. Jupiter, you're actually stealing speed from Jupiter, making its orbit slightly tighter. It's not a problem if you do it occasionnaly, but it might get dangerous when you start moving small moons around $\endgroup$ – Pierre Cathé Sep 27 at 12:33


We don't really need materials on Earth, we need energy. If we can use the materials to generate energy for Earth, we solve most of our issues.

Almost all of our air pollution is caused by energy production. If the energy could be created in space (e.g. beamed solar power), you cut out on almost all air pollution (put a cork in the cows for the rest). You could also use that energy to run CO2 and methane scrubbers to reverse damage.

Bringing materials back to Earth would just add to physical pollution.

That said, it might be worth it to bring back materials that can only be created in zero G. I have heard that "foam steel" has a very good strength to weight ratio. Also, there may be alloys that are only possible in zero G. Since substances won't separate by weight, there has been a lot of speculation about things like plastic/metal alloys. Those materials may be priceless on Earth or may just end up being a fancy way to accomplish a task that simpler and cheaper materials can accomplish.

The unknown value of material goods (aside from turning scarce metals into commodities) makes the case for bringing back energy rather than physical goods much stronger.

If you put the solar panels between the Earth and the Sun, you can also do a small bit for reducing solar energy that reaches the Earth (it would take a mega structure to have a significant impact).

  • $\begingroup$ How do you 'bring back energy'? $\endgroup$ – Morris The Cat Sep 26 at 19:11
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    $\begingroup$ I mentioned beaming solar power back to Earth. There have been plans for decades for orbiting solar arrays that use microwave beams to receiving arrays on Earth. $\endgroup$ – ShadoCat Sep 26 at 20:50
  • $\begingroup$ You can also bring energy back by using the space infrastructure to build and charge big batteries. $\endgroup$ – Geronimo Sep 27 at 12:53
  • $\begingroup$ @Geronimo, or, if you posit an in place space elevator, use really long wires. Bean the power to the elevator head and then transmit it though wires. That will keep you from roasting birds (note that the energy of the microwave beam wouldn't be dense enough to do that anyway). $\endgroup$ – ShadoCat Oct 9 at 22:39

The question is critically dependent on cost of transport.

If you wrap a conventional hull around a bunch of ore, like big ore ships, the answer is "no", at least initially.

Where travel on Earth is measured in distance,in space it's measured by delta-V: What tis the minimum delta-V to get something from one orbit to another.

Let's consider moving water from Saturn's rings to Mars. Minimum energy orbit takes years. If you do it using rockets, you need a lot of fuel.

Instead we use a rail gun. Our ice is gathered into standard 10 kg hunks, frozen, and put on a sled on the rail gun. This accelerates to to some large velocity. The sled stops, the ice keeps going. Low energy return track for the sled. Done right you have string of ice cubes a km apart moving at 30 km/s or so. Newton's laws still hold, so the rail gun is moving the other way. Half an orbit later however, it does another series to cancel the momentum change out. The over all net effect is that Saturn is boosted in a slightly higher orbit.

Similar operations can be used to ship anything around the solar system where delivery time of months to years is acceptable. Depending on tech available either finished products, refined materials, or raw rock/ice can be shipped.

Catching it at the other end can either be in orbit, or direct to planet surface. The latter is fine for ice cubes. Something gentler is needed for finished products.

As you can imagine the costs to set up this infra-structure are -- ahem -- sky high.

To boot strap this, we need to start with a very rugged nuclear rocket. Probably some form of gaseous uranium reactor to get to the necessary temperatures. Currently this is very future tech. The idea is that you use the reactor to boil rock, or to power a rail gun that throws gravel at VERY high speed. You land on an Near Earth Asteroid, set up the rocket, and the rocket and automated machinery hurls some few percent of the rock off at high speed, and modifies the orbit to get captured by the moon on it's next pass. Now you have a cubic km or so of mixed stone and iron to use for construction.

Refining will take some more work, but very large (km scale) mirrors are easy in space. And a km of mirror is about a gigawatt. Focus that down to 30 m or so, and you can melt almost anything meltable.

So is it economic? NOt with today's tech, but with reasonably foreseeable tech, I would say, yes. How long? If you have guys like Elon Musk running it, within 50 to 100 years.

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    $\begingroup$ I suspect that a lot of planetary governments would object to the delivery of materials to their planet's surface via giant interplanetary railgun. Either the products come down randomly and are hazards to anyone on the surface, or they come down in specific delivery zones, in which case the railguns become a rather alarming example of dual-use technology (en.wikipedia.org/wiki/Dual-use_technology). $\endgroup$ – Salda007 Sep 27 at 5:19
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    $\begingroup$ Probably the best way to deliver water to Mars. It is also a weapons system of fearsome capability. But asteroid settlements are very vulnerable. $\endgroup$ – Sherwood Botsford Sep 30 at 15:57

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