B Asteroid/Near Earth object mining

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anorlunda

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I mean, here's the thing with these price estimates:
With the presumed (relatively) high availability of volatiles on asteroids/comets, the investment would be all in the initial costs. After that, any fuel should be able to be extracted on site, and after the initial investment (which will be verrry high), it should be mostly profit. You don't have to send a new miner into space every asteroid. You just send the old one to a new asteroid when it's done. Fuel it up with the stuff you've gotten off of other asteroids, and keep going. 1 investment, infinity profits. ;)
Come on. You are visualizing autonomous, robust, long lived, self reparing robotic mining/refining/manufacturing machines. I challenge you to make such a machine even on Earth. As a pilot project, build a machine to bore a tunnel under the Atlantic from America to Europe, and to do it fully automated and self powered and without the assistance of human hands. When you have achieved something comparable to that, I'll be more receptive to doing it in space.
 

BiGyElLoWhAt

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They don't necessarily have to be 100% autonomous, we can still communicate with them and tell them what to do, where to drill, where to go, what to keep, what to pitch. It just takes a bit to get the message there.
We're obviously not going to be able to send people to the asteroid belt. So it's either going to happen by a) autonomous robots, or b) human controlled, highly automated robots. If you can think of a 3rd option, let me know. I guess we could just send all the asteroids to the moon and then mine them there, if that's what you're thinking? That would allow us to use humans to mine them.

The concept of automated mining is already in development.
http://ade.sagepub.com/content/7/2/504861.abstract

I'm not claiming that it will be easy, but it's definitely feasible.
 

anorlunda

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The concept of automated mining is already in development.
Automated mining is not mining plus refining plus manufacturing, nor is it self-repairing or self-powered. Have you thought of the energy required to pulverize 100 tons of ore?

The article you linked is very far from sufficient basis to claim "definitely feasible."
 

BiGyElLoWhAt

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Well, self-repairing is also a stretch. I really doubt one machine will do all of these things. I bet we could make an automining bot, and I bet we could make an auto refining bot, and I bet we could make (probably several) bots that could repair things. It's not anywhere near, but I have no doubt that it can be done. At that point, the only problem is getting it into space.
As for pulverizing 100 tons of ore, that's not necessarily necessary. Drilling is also a possible option, depending on whether or not the ores run in veins. I'm not sure how much energy it would require, but I'm sure it would be a lot.
 
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At that point, the only problem is getting it into space.
Where is the point in putting it into space if you can use it on Earth? A cubic kilometer of randomly sampled soil on Earth has gold with a current market price of $1 billion, and tens of billions if you look in the right places. Unless access to space gets massively cheaper and robots get much more flexible and intelligent, mining on Earth will stay cheaper for quite some time.
 

BiGyElLoWhAt

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Yes, but that will eventually run out, albeit probably long after I'm dead. We keep growing, which warrants a higher demand for resources, which means that the rate of consumption will also go up. Eventually, it won't be sustainable to keep mining the earth.
 

russ_watters

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I mean, here's the thing with these price estimates:
With the presumed (relatively) high availability of volatiles on asteroids/comets, the investment would be all in the initial costs. [Snip], and after the initial investment (which will be verrry high), it should be mostly profit.
If that sort of PPM (Perpetual Profit Machine) were possible, people would already be doing it on earth.
After that, any fuel should be able to be extracted on site.
So asteroids have fuel on them now too?! Awesome!
 

russ_watters

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Yes, but that will eventually run out, albeit probably long after I'm dead. We keep growing, which warrants a higher demand for resources, which means that the rate of consumption will also go up. Eventually, it won't be sustainable to keep mining the earth.
"Eventually". Great. So let's table this issue for now and check back on it in 100 years, when autonomous space mining is technically possible and gold costs a million dollars an ounce.
 
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So asteroids have fuel on them now too?! Awesome!
Russ Watters, I believe BiGyElLoWhAt was referring to the water ice available on asteroids, he may have meant that some asteroids contain the ingredients (water) for bi-propellant (LOx/LH as I am sure you know) rocket fuel. I understand that it would have been more appropriate for BiGyElLoWhAt to say that some asteroids have suitable reaction mass for spacecraft to refuel with (after the water has been split) I assume (correct me if I am wrong) that rather then calling him out on the statement that some asteroids contain water you were instead calling him out for calling water 'fuel'. I think I understand where BiGyElLoWhAt was coming from, he probably just meant the 'ingredients for rocket fuel'. :)
If that sort of PPM (Perpetual Profit Machine) were possible, people would already be doing it on earth.
I agree, in my opinion bringing resources back to Earth is NOT yet, or soon to be feasible, or even making space craft in space for that matter. Luckily water is a bit easier to refine into rocket fuel than trying to process ore into usable building materials.

Edit: In fact, it is my understanding that refueling spacecraft with rocket fuel manufactured IN SPACE is the MAIN draw of interest toward (serious/(maybe) feasible) asteroids mining, Imagine a probe being able to stop and refuel at a 'gas station' on its way to explore the solar system! It would sure cut back on unreasonably large launch stages in some scenarios. (opinion alert) Now to ME that sounds like a sound investment ONCE the technology gets there! Defiantly not mining platinum group metals. :D
 
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Why LH2/LOX as a rocket propellant?

LH2 has a boiling point of 20 K at 1 bar, and a critical point of 33 K and 13 bar, so it is hard to keep it liquid.
LOX has a boiling point of 90 K at 1 bar, and a critical point of 155 K and 50 bar, so it's easier.
The critical point is where the liquid-gas phase transition disappears. Above its temperature, a substance cannot be liquefied.

Also, the best exhaust velocity that one can do with it is about 4.5 km/s (RD-0146 rocket engine; the Space Shuttle Main Engine and other LH2/LOX engines have similar values). From Tsiolkovsky's rocket equation, one can reduce one's propellant consumption by increasing one's exhaust velocity. That can be done by using an electric rocket engine. The Dawn spacecraft's NSTAR ion engines can do 30 km/s. A kind of coilgun called a mass driver may be capable of at least 20 km/s.
 
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Why LH2/LOX as a rocket propellant?

LH2 has a boiling point of 20 K at 1 bar, and a critical point of 33 K and 13 bar, so it is hard to keep it liquid.
LOX has a boiling point of 90 K at 1 bar, and a critical point of 155 K and 50 bar, so it's easier.
The critical point is where the liquid-gas phase transition disappears. Above its temperature, a substance cannot be liquefied.

Also, the best exhaust velocity that one can do with it is about 4.5 km/s (RD-0146 rocket engine; the Space Shuttle Main Engine and other LH2/LOX engines have similar values). From Tsiolkovsky's rocket equation, one can reduce one's propellant consumption by increasing one's exhaust velocity. That can be done by using an electric rocket engine. The Dawn spacecraft's NSTAR ion engines can do 30 km/s. A kind of coilgun called a mass driver may be capable of at least 20 km/s.
That's a really interesting point! I am now very curious whether or not some asteroids have suitable noble gasses for use in an Ion engine, surely they do, are they easy to extract and purify? Could you use non-noble gas reaction mass in an ion engine as well? I do however have trouble understanding how a rail gun could be used in this situation though because the way I see it (liable to be incorrect of course) you have to manufacture projectiles, which would bring us back to the problem of refining metals in situ... How scalable are ion engines for hypothetical 'large' future space craft? I (unfoundedly) just assumed that ion engines came in small sizes. Now I see the error in my ways. Are ion engines good for moving large payloads with short burns? Is a draw to LOX/LH2 bipropellant the short thrust times? If not why do we still use bipropellant (on probes that is)? Thanks Lpetrich! :)
 
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About mining robots, I concede that a self-repairing one may be too farfetched. But a community of robots that can repair each other may well be feasible.

But I'd like to see that demonstrated under conditions similar to an asteroid mine. Conditions like having no human assistance outside of communications with about an hour of round-trip time.
 
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I did some more checking. Dawn has three NSTAR ion engines, and each one has a thrust of 90 millinewtons. That's enough to lift 9 grams off of the Earth's surface. Dawn's ion engines were run for much of the spacecraft's mission, going from the Earth first to Vesta, and then to Ceres. The engines also got the spacecraft into orbit around Vesta, out of Vesta orbit, and then into Ceres orbit. However, Dawn was sent into space on a Delta II, a typical chemical-propulsion booster rocket.

As to xenon, it is *not* a very common element in the Solar System: Abundances of the elements (data page) - Wikipedia and my previous links on overall composition. It is also relatively volatile, so the best place to look would likely be in comets. Argon is even more volatile, but there is enough of it in comets to be detected.

As to making projectiles, the solution hit on by Gerard K. O'Neill and others is to use buckets that would interact with the gun coils. These would be filled with material, accelerated, and then decelerated and returned. The material would keep going.
 
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Why LH2/LOX as a rocket propellant?
LH2/LOx works without needing (significant) additional energy sources. Ion thrusters need some power source - typically photovoltaics - and they produce extremely small thrust limited by that power source.
 

D H

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So asteroids have fuel on them now too?! Awesome!
Yes. I hinted at that back in post #24 where I wrote "What might be viable in the near-term future is harvesting volatiles such as water and methane from those asteroids and then finding a way to use those volatiles in space." One obvious use is as fuel.

In fact, it's the volatiles rather than the metals that are the low hanging fruit with regard to asteroid mining -- assuming we can find a way to use those volatiles. The mining and refining capabilities aren't near as extensive as would be needed for mining metals. However, In order for those materials to be useful they need to be used in space, and that requires an already existing infrastructure in space. This is a bit of a chicken and egg problem. Those volatiles possibly could be used to bootstrap that infrastructure.
 
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Useful for what? Are you proposing that we make spacecraft factories in space? , Electronic chip foundries in space? Suppose you had 100 tons of iron ore in lunar orbit. How would you refine it? What would you do with the refined steel?
I don't know that it would be more cost-effective to set up an entire assembly tower in orbit, but being able to set up some basic infrastructure in space to make simple yet heavy things like structural components might help to greatly reduce the cost of construction in space.

I don't think it's iron & silicon we're after... Those are abundant "useless" minerals. What we want are the moon-sized diamonds floating around out there & the asteroids made of solid platinum.
The point isn't that they're rare, it's that they're heavy and needed in large quantities. The cost of a launch increases exponentially with payload weight, so it might be far more efficient to send up, say, 5 tons of extraction and refining equipment than 100 tons of refined iron and silicon.

As for moons and asteroids made entirely out of diamond and platinum, I don't really know that that would actually be as profitable as it sounds, since the sudden change from being in precious supply to being in effectively infinite supply would crash the price of those minerals to near nothing.
 
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The cost of a launch increases exponentially with payload weight
It is not exponential, it is not even linear - it is slower than that. Sending up twice the amount does not cost twice as much.
As for moons and asteroids made entirely out of diamond and platinum, I don't really know that that would actually be as profitable as it sounds, since the sudden change from being in precious supply to being in effectively infinite supply would crash the price of those minerals to near nothing.
It would set the price to the costs to extract the materials. Business as usual - if those costs are below the market prices that we have without asteroid mining.
 
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And another look from a different perspective.
 

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