Asteroid/Near Earth object mining

[mfb]

For platinum:
The Sun: 9.*10^(-7)%
Meteorites: 9.8*10^(-5)%
The Earth's crust: 3.7×10^(-6)%
Apparently by weight; the Sun is listed as having 75% hydrogen and 23% helium.

Though meteorites contain about 30 times more platinum per unit mass than the Earth's crust does, it's still a tiny amount: 1 part per million. So to get 1 kg of platinum, one needs to mine 1000 tons of meteorite material. Checking on Platinum Price | Platinum Price Chart History | Price of Platinum Today | APMEX, I find that platinum's typical price as I write this to be around $31,000 / kg. So it will be hard to justify the expense of sending mining machines off of the Earth and to the asteroids.

It gets worse. On Earth, chemical processes tend to enrich elements. You don't need to take a representative sample, you can build your mines at places with the highest concentrations. For platinum, that is in the multiple ppm range (example: 6 g per ton), or x*10^-4% - better than the meteorites.

 

[anorlunda]

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

There was scientific speculation that the entire core of Jupiter might be a single crystal diamond with mass more than Earth. All you have to do is to figure out how to get it out of that gravity well, then to calculate the new price per carat of diamonds after that hits the market. The semi-serious point is that some rare things are valuable only because of their scarcity. If you find an abundant supply, then their high value vanishes.

redirecting asteroids that pose a threat sounds like a good idea

Indeed it would sound good except that any such capability has intrinsic potential use as a weapon.

 

[lpetrich]

Is this an average of the platinum per unit of mass, of all asteroids? It is (was) my understanding that some asteroids are more abundant in some materials than others. Thanks. :)

That's indeed an average over asteroids, yes. But I've found some numbers on platinum concentrations in individual meteorites:

The distribution of platinum and palladium metals in iron meteorites and in the metal phase of ordinary chondrites - jgr4710.pdf
The platinum group metals in iron meteorites - 02_whole.pdf -- Appendix 2c gives a list of Pt concentration measurements in micrograms per gram.

Most meteoritic platinum is concentrated in iron meteorites and the iron parts of stony-iron ones. I looked over the numbers in the second paper, and the Pt concentrations vary between around 1 and around 30 micrograms/gram of meteorite. The rough average of 10 μg/g is about 10^(-5). That means that you need to mine only 100 mt of meteorite to get a kg of platinum, and sometimes only 30 mt -- still a lot.

 

[lpetrich]

So the best meteorites are at 30 grams/ton.

Let's look at launch costs. SpaceX has a page on Falcon 9's http://www.spacex.com/about/capabilities. Here are the numbers that that company states:

• Low Earth Orbit: 22.8 mt
• Geosynchronous Transfer Orbit: 8.3 mt
• Escape to Mars: 4.02 mt

with a stated cost of $62 million per launch, for up to 5.5 metric tons to GTO. Here's the cost per kg:

• LEO: $2700
• GTO: $7500
• Mars: $15400

So to launch from the Earth to the asteroids is at somewhere around 1/2 the current price of platinum.

 

[D H]

There was scientific speculation that the entire core of Jupiter might be a single crystal diamond with mass more than Earth.

Much closer to home, there's a huge reservoir of gold, platinum, and other special metals that is a mere 6000 or so kilometers away. All one has to do is develop the technology to dive down to, extract the resources, and then come back from the Earth's core. Even closer to home, there is huge (but not quite as huge) reservoir of gold, platinum, and other special metals in the Earth's oceans. This too is utterly worthless.

With the possible exception of helium 3 and unobtainium, mining materials from space and bringing them down to Earth currently does not make sense economically, and will not make sense economically for a long, long time. What might make sense is to mine materials in space and use most of that material in space. Sending a bit back to Earth might then make sense.

 

[Hoophy]

I would assume that is true...which means someone will also need to invent prospector robots and fund their activities.

http://www.space.com/29975-asteroid-mining-planetary-resources-satellite-launch.html
A small start, but a start nonetheless.

Also I found this interesting: http://web.mit.edu/12.000/www/m2016/finalwebsite/solutions/asteroids.html

What might make sense is to mine materials in space and use most of that material in space. Sending a bit back to Earth might then make sense.

I agree, it would be nice to refuel spacecraft in space with LOX/LH bipropellant. But as earlier mentioned, it is only feasible if it is cheaper to manufacture fuel once in space than to bring it from Earth.

 

[mfb]

Also I found this interesting: http://web.mit.edu/12.000/www/m2016/finalwebsite/solutions/asteroids.html

I wonder if they do that on purpose (my guess: yes):

According to the KISS study, the cost for a future mission to identify and return a 500 ton asteroid to low Earth orbit is ~$2.6 billion USD, ignoring the costs to develop the infrastructure necessary to process the materials in the asteroid ("Asteroid usage", 2012). However, Planetary Resources estimates that a single 30 meter long platinum-rich asteroid could contain $25 to $50 billion USD worth of platinum at today's prices (Klotz, 2012). Clearly, once the proper infrastructure is in place, there is potential for significant profit.

Want to compare the two USD values? Well, a (spherical) 30 meter asteroid will have a mass of about 20,000+ tons, not 500 tons. Also, $25 billion in platinum would be 700 tons. A 3% platinum concentration sounds unrealistic.

 

[Hoophy]

Want to compare the two USD values? Well, a (spherical) 30 meter asteroid will have a mass of about 20,000+ tons, not 500 tons. Also, $25 billion in platinum would be 700 tons.

I honestly can not tell whether or not they are referring to the same size asteroid in the two estimates. If not why did they not standardize the predictions? Odd...

A 3% platinum concentration sounds unrealistic.

I agree.

 

[D H]

I wonder if they do that on purpose (my guess: yes):

It was from two very different sources. One was a somewhat realistic study on what it would cost to bring a 7 meter diameter asteroid massing about 500 metric tons to high lunar orbit. Another was a statement based on unrealistic assumptions intended to garner investors.

Well, a (spherical) 30 meter asteroid will have a mass of about 20,000+ tons, not 500 tons. Also, $25 billion in platinum would be 700 tons. A 3% platinum concentration sounds unrealistic.

Your 700 tons for $25 billion in platinum uses current prices, which are less than half of what they were in 2008 (~$2400 per troy ounce in 2008, about $1600 in 2012, versus versus about $1000 today). Precious metal prices are extremely volatile. Bringing back 3.5 times the 200 metric tons of platinum mined worldwide in 2015 would add a tiny bit of volatility to the markets (written with tongue in cheek). That volatility would of course make that asteroid worth even less.

Assuming the first study's $2.6 billion to retrieve a 500 metric ton asteroid was roughly correct and assuming that costs scale linearly with mass, bringing back a 20,000 ton object would cost about $100 billion. (Note: This is a bad assumption. There are significant diseconomies of scale when it comes to large-scale space exploration.) Receiving a ridiculously optimistic $50 billion as a result of that investment is a way to quickly turn the richest of investors into paupers.

Regarding your last figure, it's not just unrealistic. It's beyond ridiculous.

 

[mfb]

Your 700 tons for $25 billion in platinum uses current prices, which are less than half of what they were in 2008 (~$2400 per troy ounce in 2008, about $1600 in 2012, versus versus about $1000 today).

I took the lower USD estimate, so a factor of 2 in the platinum price is still within the given range.

Bringing back 3.5 times the 200 metric tons of platinum mined worldwide in 2015 would add a tiny bit of volatility to the markets (written with tongue in cheek). That volatility would of course make that asteroid worth even less.

Well, if you are the only one doing it you can spread the mining over several years (if you are not the only one doing it, it is profitable anyway). But just the announcement that you have 700 tons of platinum in Earth orbit will probably make the price drop.

There is not just platinum, of course, but with the current cost estimates and market prices it is still too expensive.

 

[1oldman2]

Forgetting all the speculation on practicality, I'm wondering about the real plans at the present.
http://www.nasa.gov/content/what-is-nasa-s-asteroid-redirect-mission

 

[russ_watters]

Assuming the first study's $2.6 billion to retrieve a 500 metric ton asteroid was roughly correct and assuming that costs scale linearly with mass, bringing back a 20,000 ton object would cost about $100 billion. (Note: This is a bad assumption. There are significant diseconomies of scale when it comes to large-scale space exploration.)

Because of the scaling issue, let's close the loop from the other direction: Assuming $2.6 billion to bring back the 500 metric ton asteroid is correct (and noting it doesn't include the cost to mine the asteroid!), it would hold (at 3%) 15 tons or $500 million worth of platinum.

Well, I'm ready to invest! Who's with me?!

 

[mfb]

It's fine, just assume -2.1 billion mining operation costs.

 

[1oldman2]

Hi everyone,
While NASA's A.R.M. seems primarily geared towards developmental testing of tech that will be used in the upcoming Mars missions, as well as redirecting potentially Earth threatening asteroids, they do mention future asteroid mining as benefiting also. Considering NASA as well as Caltec/Keck, DSI, Planetary resources as well as many other "less than crackpot" entities are actively promoting the concept of mining asteroids I assume its going to happen. One thing for certain here is we are discussing events that not many of us will be alive to witness, (Hoophy just may be an exception ). The mining of asteroids in the current context of economics and technology may seem a lot like Sci-Fi however anyone with a little historical perspective will note that what's common today was Sci-Fi not long ago. While investing in the start up of asteroid mining isn't likely to be a quick turn around on your buck, your grandchildren would be very happy to inherit your stock once the infrastructure is in place.
I'm glad to see this thread eliciting such spirited banter
Now I'll return to my current research project which involves the effects of high gravity beer on micro-gravity viewing at Live-ISS-Stream. Cheers !

 

[BiGyElLoWhAt]

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. ;)

 

[anorlunda]

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]

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]

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]

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.

 

[mfb]

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]

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]

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]

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.

 

[Hoophy]

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 spacecraft 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

 

[lpetrich]

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.

 

[Hoophy]

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! :)

 

[lpetrich]

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.

 

[lpetrich]

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.

 

[lpetrich]

Variable Specific Impulse Magnetoplasma Rocket - Wikipedia (VASIMR). The most recent model of it is expected to do 50 km/s of exhaust velocity and 5 Newtons of thrust with argon, enough to lift 500 g off the Earth's surface. It has been tested in vacuum chambers on the ground, but still not in space.

 

[mfb]

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.