Small Near-Earth Asteroid Surfaces Have Few Precious Metals, Study Finds (arxiv.org) 44
RockDoctor (Slashdot reader #15,477) writes:
A recent paper on ArXiv reports new spectroscopic analyses of the surfaces of 42 asteroids. The main result for space enthusiasts is that there is not one "M" class asteroid (metal-rich) surface in the collection.
The imagery that (many) people grow up with from Hollywood and TV "science" "documentaries" is that the Solar system is full of asteroids which are made of metal ready for mining to produce solid ingots of precious metals. That's Hollywood, not reality. This result is about what you'd expect from the proportion of metallic asteroids — otherwise estimated at about 0.5% of the population.
The asteroid mining fraternity dream of taking apart an M-type asteroid like Psyche, which is fair enough as a dream. Even as a dream for "asteroid mining" metal market speculators. But they are relatively rare asteroids. A realistic "ISRU" (In-Situ Resource Utilisation) plan is going to have to expect to digest around 200 silicate mineral (and clay ("phyllosilicate"), and ice) asteroids for every metallic one they digest.
Here's the home page for the project.
The imagery that (many) people grow up with from Hollywood and TV "science" "documentaries" is that the Solar system is full of asteroids which are made of metal ready for mining to produce solid ingots of precious metals. That's Hollywood, not reality. This result is about what you'd expect from the proportion of metallic asteroids — otherwise estimated at about 0.5% of the population.
The asteroid mining fraternity dream of taking apart an M-type asteroid like Psyche, which is fair enough as a dream. Even as a dream for "asteroid mining" metal market speculators. But they are relatively rare asteroids. A realistic "ISRU" (In-Situ Resource Utilisation) plan is going to have to expect to digest around 200 silicate mineral (and clay ("phyllosilicate"), and ice) asteroids for every metallic one they digest.
Here's the home page for the project.
Re:Just as well. (Score:5, Insightful)
> Easy access to precious metals from space would completely disrupt the world economy.
If it were easy, it'd be inevitable.
Until space elevators happen, we don't need to worry.
And? (Score:2, Interesting)
I'd rather have value be from the result than from physical scarcity. It'd be one more reason (yes there are many) to get rid of copyright and other monopoly giving powers, and start Universal Basic Income.
People shouldn't have to sell all their waking hours (and their whole future) to faceless corporations that will drop them the moment it's useful to. It should be an actual choice, with more positives than negatives. I can't say I've felt that way for long in my whole life.
Even at my most "successful"
Re:Just as well. (Score:5, Interesting)
Like Mansa Musa [wikipedia.org], who personally disrupted the Egyptian economy by spending gold so lavishly while on the Hajj? ;)
I don't get the logic that you'd have to "have to expect to digest around 200 silicate mineral (and clay ("phyllosilicate"), and ice) asteroids for every metallic one they digest". Nobody is holding a gun to anyone's head and making them pick asteroids at random. It's a weird comment. So 0,5% have metal at the surface? Great, we'll go to those ones. Maybe they're not the lowest dV choices, but they're still choices.
IMHO, it's been clear to me that for the forseeable future, any asteroid mining is going to have to *dramatically* minimize local processing and leave that for earth. So that means gathering already-loose regolith, magnetically sifting it (in a centrifuge - too little gravity to rely on that to drain-away non-magnetic fines), sintering the magnetic fines, and... doing nothing elsewhatsoever to them apart from returning them to earth. No refining - the consumables supply chain is just far too complex.
And since it's unlikely you'd be able to afford propellant and the capital cost of rockets spending months per trip for such "cheap" commodities, then you're looking at firing them back, such as with a coilgun or quench gun. Which - thankfully - since your magnetic fines are iron-based, the payload can itself be the projectile. And more to the point, if properly shaped (and hollow, for a high surface area to mass ratio), it can be its own heat shield for entry as well**. That said, one can expect the landing elipse to be far too large on Earth, so you'd instead need to fire onto an aerocapture trajectory to a highly elliptical Earth orbit, and have a space tug nudge them onto a precise landing trajectory.
** Even large natural meteorites [wikipedia.org] can land survive with large masses intact just through a lucky trajectory - without being shaped into an aeroshell and without being hollow.
Gathering minerals is also a challenge in microgravity, even if one is just collecting loose regolith. I think your best bet would be, so long as there is anything resembling "bedrock" (large boulders), to cement dragline towers to said boulders. Three towers can allow one to position a collector to any location between them and provide the counterforce needed to raise and lower the bucket, steady it while it ejects nonmagnetic fines, and bring it back to the sintering facility. If there is no bedrock, on small bodies you could run lines or net around the whole asteroid's diameter, or sink piles (though they'd need to be very long).
Re: (Score:3)
Of course, from the Earth perspective, the "mine" is really simple: some big worthless brackish lake or shallow seabed in some god-forsaken area where nobody will care if you keep slamming spacecraft-sized chunks of metal into the water. Your Earthside-"mine" is thus just an electromagnet hanging off a boat for loading large hollow aeroshells of platinum-rich nickel-iron onto the deck. Versus a standard Earthside platinum mine, it's no overburden, no smelting, and 2 orders of magnitude higher platinum conc
Re: (Score:2)
...loading large hollow aeroshells of platinum-rich nickel-iron onto the deck...
Keep in mind that "platinum rich" means many parts per million platinum.
This is not hunks of platinum waiting to be picked up like pebbles. It is hunks of mixed nickel and iron, with a tiny bit of platinum (and platinum group metals) dissolved in.
Re: (Score:3)
"Many" parts per million is a heck of a lot better than even good platinum deposits on Earth, which are generally just a few ppm and buried deep under extensive overburden. Whole groups of meteorite samples have dozens of ppm platinum, up to well over 100ppm in exceptional samples. No, it's not just any random asteroid that offers that potential, but again, one can choose.
And given that the post you're responding to says "platinum-rich nickel-iron", I'm not sure who you think you're responding to with you
Re: (Score:2)
"Many" parts per million is a heck of a lot better than even good platinum deposits on Earth, which are generally just a few ppm and buried deep under extensive overburden.
This is not at all clear. Overburden is a problem that's been solved, you sort out the stuff you want. The platinum in meteorites, however, isn't in the form of high-assay platinum metal nuggets that you just have to sort away from the other stuff, it is platinum group metals in solid solution in the nickel-iron matrix. It is a common belief in the space community "oh, we just have to sort out the platinum atoms from the iron and nickel atoms, how hard could that be?" but there's no actual demonstration tha
Re: (Score:2)
I think you need to look up the definition of overburden.
You don't "sort" overburden. It doesn't contain your target mineral. You have to remove it - even if it's hundreds of meters thick - or excavate mine shafts (accepting a much lower throughput).
Um, yes, it ra
Re: (Score:2)
Have a nice day.
Re: (Score:3)
I'm waiting for people to realize the material is far more useful at the top of Earth's gravity well than at the bottom, but we're not there yet.
Re: (Score:2)
Without in-space manufacturing, it absolutely isn't. And our (epicly massive) manufacturing supply chains are sitting here on Earth's surface.
Re: (Score:2)
Re: (Score:2)
It looked rather different when I submitted it. EditorDavid was the one who mentioned "precious" metals ; the study itself was about "any" metals - particularly nickel-iron (by far the most common metals found as elements/ alloys).
If you're looking at an asteroid with spectroscopically visible surface quantities of nickel or iron, then on average there will be 200 metal-poor asteroids that are closer, have a lower minimum or
Re:Just as well. (Score:4, Insightful)
It's not happening any time soon. Even if very high grade ore were found in a nearby asteroid, or even the Moon, it would not be brought to market. Retrieval is too expensive. Just getting to LEO is about $3k/kilo. Gold is roughly $60k/kilo, but that's *pure* gold. Now consider that retrieval from Solar orbit is going to cost a lot more than LEO, and it's not pure gold up there. It's ore. Even if it's an incredibly rich ore, like 10% gold (pretty much unheard of) it's now worth only $6k/kilo and costs at least twice as much to get back, probably more.
A remote refinery helps, but we're still happy to just dig tiny little holes on Mars, or blow up a tiny piece of an asteroid. A practical remote prospecting, mining and refining operation seems like a 50 year task at least.
I'm not saying never. Just not any time soon.
Re: (Score:2)
Firing a coilgun / quenchgun of an unguided shell comprised of your return material costs just electricity and maintenance. Electricity in turn is just amortized capital cost plus maintenance. So there's really only one question: what your throughput is relative to your capital and maintenance costs.
You seem for some reason to be positing "retrieval" even though the post you're responding to specifically states "it's unlikely you'd be able to afford propellant and the capital cost of rockets spending mont
Re: (Score:3)
- like technology to smelt aluminum - when suddenly it was posible to make everyday product with it instead of only jewellery for the richest?
- like technology to mine iron ore and smelt it, so people could start using it for everyday product and be on the front site of the industrial revolution instead of only having meteorite for weaponry and jewelry for the richest?
- like growing potatoes in Europe, so peasants could have a nutritional meal instead of it being the overseas rarity on the kings' tables?
- l
Re: (Score:2)
Easy access to precious metals from space would completely disrupt the world economy. You think the SVB crisis is bad? It would be peanuts.
The sudden availablity of large amounts of resources is not something that should cause damage to the world economy. If it does, then there is something seriously wrong with that economy, and it would be a good thing to disrupt it. In reality, access to large quantities of previously available resources should stimulate the economy and improve things. Sure, specific institutions that rely on the status quo might not do so well. For example, companies and stocks heavily invested in conventional mining on Ear
you only need one (Score:4, Informative)
Re: (Score:2)
You know, I normally think about how one would sinter regolith into hollow aeroshells and eject them onto Earth aerocapture trajectories...but imagine the haul if you could turn a whole (small!!!) metallic asteroid into a hollow, stable aeroshell-shaped entry body and redirect it to a minimum-energy entry trajectory. You'd need to have a landing ellipse where nobody's going to mind if you make really big waves on splashdown, mind you! But it'd (pardon the pun) cause global platinum-group metal costs to cra
Hollywood? (Score:2)
Despite the summary's claims, I don't recall a plethora of movies featuring metal-rich near-earth asteroids.
Re: (Score:1)
Despite the summary's claims, I don't recall a plethora of movies featuring metal-rich near-earth asteroids.
Nothing really comes easily to mind except perhaps The Expanse ...
Re: (Score:2)
Despite the summary's claims, I don't recall a plethora of movies featuring metal-rich near-earth asteroids.
Nor movies or scientists saying most asteroids have useful minerals. What I recall is prospecting, have to go find one that has something useful.
That said, 0.5%, 1 in 200, is huge given the number up there.
Heavy (Score:1)
Metallic elements are heavy and would not tend to be on the surface of said asteroid... Just saying.
Re: (Score:3)
As a general rule, metallic asteroids are undifferentiated. So yes, they are.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Yes, iron is the "most stable nucleus" (in terms of binding energy per nucleon) so it is the end point of the nucleosynthesis chain. In the microseconds before a star goes supernova,
Crystalline Space Stations (Score:2)
First you see what resources you have available, then you figure out how you can use them.
If there's that much silicon to be had, we figure out how to grow large usable crystals in space to use for structures. If it's easier to get iron or aluminum, we use that.
Yeah, yeah, Kryptonians [blogspot.com] already did it.
Without worrying about beauty initially, if we can turn an asteroid into a quartz countertop as a first pass, at least we can cook the space worms.
Re: (Score:2)
excuses.
are for those who can not.
for others.
it is a fertile field of what can be used to further accomplishments
Re: (Score:2)
I wanted to say something similar. Even if it's not iron, it's mass and it's already out of Earth's gravity well. We can figure out what to do with it - even if it's turning it into something like concrete structures - that's valuable, too.
Re: (Score:2)
(Also, thank you EditorDavid for uselessly adding "precious metals" to my original submission, a point I only held in scorn.)
Magnetic separation would work,
Re: (Score:2)
Silicon, on it's own, is very uncommon on Earth, or in space. It is almost always combined with oxygen into silicate minerals - the most common being olivine which has one (Mg or Fe) atom, one silicon atom, and approximately 4 oxygen atoms. (The oxidation state of the iron, +2 or +3, being the reason for "approximately".)
Extracting metallic silicon from silicate minerals is appreciably harder than extracting iron from iron ores. That's why ("rocky") planets (and aste
Ice is nice. (Score:4, Informative)
Re: (Score:2)
It's a bit more complicated than that, because the pressure of the inner solar system is so low, materials are meaningfully volatile - they're sublimate and blow away in less than millions of years - as much as 50K below their sea level melting points. It's further complicated because only a thin layer of mineral dust (millimetres to a couple of centimetres) is sufficient to stabilise "vo
Sounds like pretty good odds to me. (Score:3)
One out of 200? When you have millions? If you told me I could dig 200 holes and have a 50% chance of finding a platinum mine, I'd grab a shovel right now.
Re: That's not how it works (Score:2)
This. The value is in the fact that there are a LOT of asteroids and they're relatively soft for digging (assuming you've dealt with how to dig on an asteroid is such low g's in the first place). Then you have surveys just like this one to find the rich asteroids and get digging. Will there be solid gold asteroids? Unlikely. But there could be ones that have value depending upon current metal needs.
Re: (Score:2)
The actual purpose of this survey was to try to determine the surface composition of asteroids likely to be near to Earth in the relatively near future, which are the ones we're going to need to use to build up the space-based industries we'll need to be able to reach the more distant asteroids and then the rest of the Solar system. We'll use what we can reach, because we can't use what we can't reach.
They can only see the outside, right? (Score:2)
Is it possible the outsides won't tell us what is inside?
How likely is it that a substance we care about would be on the outer edge vs. being hidden inside? I'd guess that would depend on the strength and brittleness of the substances we hope to extract vs. the cruft we don't.
Go big or (Score:2)
Just need to find one hibernating Android (Score:2)
And I bet he'd be your bestest friend ever.
https://memory-alpha.fandom.co... [fandom.com]
And how many hills have useful ore .... (Score:2)
"estimated at about 0.5% of the population"
That's 1 in 200, given the number of asteroids up there that is an incredibly huge number. And I seem to recall the word "prospecting" used quite often in association with asteroids and useful minerals, so the premise that most are expected to have useful amounts of something is erroneous.
How many hills on earth have useful quantities of some ore that justifies mining? I'm going to guess less that 0.5%.
nonsensical (Score:2)