Practically getting an asteroid full of platinum down to Earth

[SomeGuy12]

Let's suppose you find an asteroid that is several percent platinum, and work out a reasonable dV pool shot to get the thing into Earth's sphere of influence.

I can only think of one practical way to harvest it with today's technology. You launch a robotic mission to the asteroid with some kind of ultra high ISP engine, like that ion engine that has an exhaust velocity of 210 kilometers/second (dual stage 4 grid). It lands, docks by connecting itself to solid rock with a drill (which is harder than it sounds as the ESA found out recently), and then over a period of years performs the burns to redirect the asteroid.

Bringing the fuel along might be impractical, it would be nice if the asteroid itself had a few tons of ice you could harvest. You'd electrolyze the ice, and have an array of several VASIMR thrusters, some using pure oxygen and some using pure hydrogen as propellant. (or you would alternate)

Anyways, so here it is headed towards Earth. Launch spacecraft to dock with it, collect the platinum and send it down? Nope. Spend fuel braking the asteroid? Nope. You'd do just 2 things :

1. Detach the nuclear reactor that powered the engine and send it on a course that will flyby Earth

2. Send the thing to crash on land into the desert of kazakhstan at several kilometers/second.

Lithobraking will hopefully embed the platinum into a crater that is close enough to the surface so you can go scoop it up.

[shynung]

Four words. Nuclear Salt Water Rocket.

Forget the puny DS4G thruster. This thing will get it to the surface via propulsive landing without much problem.

[m4v]

after getting that much platinum its price will crash so not that practical the whole endeavour is.

[Dodgey]

after getting that much platinum its price will crash so not that practical the whole endeavour is.

Only if it is distributed. Same deal as diamonds. If the world's supply was distributed it wouldn't be worth what it is today but one company has a monopoly on it so they are able to control the demands.

[lajoswinkler]

You can't compare platinum with diamonds. Diamonds are not nearly that rare as platinum, and you find them formed, just like people who will give lots of money for them will use them - as huge bling.

Platinum is rare, dispersed (requires enormous concentration) and is actually turned into products of vital importance to the society. No platinum and we're basically ruined. Agriculture would suffer enormously, because platinum is used to make catalysts that make the nitrates synthesis a lot cheaper than it used to be in the past.

No big diamonds? Rich people's egos are ruined.

[Dkmdlb]

after getting that much platinum its price will crash so not that practical the whole endeavour is.

Can I just ask - are you saying that there is no way to avoid that price crash? Because I can think of a way, and it only took about 2 seconds to figure out.

[MinimumSky5]

Can I just ask - are you saying that there is no way to avoid that price crash? Because I can think of a way, and it only took about 2 seconds to figure out.

Platinum, like Lajoswinkler said, isn't just used because its pretty, its a vital catalyst in industry, several cancer fighting drugs can be created from it, and it is vital in electronics as it has the highest corrosion resistance of any metal, so if someone was hording platinum, governments would force them to release it.

[tater]

You'd use the cheapest technology to put in in orbit (lunar, or a Lagrange point). You could then mine what you want, and debit small mounts (many 100s of kgs) at a time with heat shields and parachutes.

In the case of Pt, you'd want to play at being DeBeers, and trickle it into the economy anyway. Dumping a ton would drop value.

[Bill Phil]

Platinum, like Lajoswinkler said, isn't just used because its pretty, its a vital catalyst in industry, several cancer fighting drugs can be created from it, and it is vital in electronics as it has the highest corrosion resistance of any metal, so if someone was hording platinum, governments would force them to release it.

Isn't platinum also used in some automobile engines?

[vger]

In the case of Pt, you'd want to play at being DeBeers, and trickle it into the economy anyway. Dumping a ton would drop value.

Much of the DeBeers 'conspiracy' relied on more artificial means of inflating the price though. #1, making people think diamonds are actually rare, and #2, inventing a tradition that makes ownership of it more or less mandatory.

The "wedding ring" trick is probably never going to work again - not as well as it did with diamonds anyhow. And keeping the wool over everyone's eyes about its rarity is going to be very difficult with an asteroid that anyone could aim a telescope at.

[Nibb31]

It might be useful for some industrial applications, because it has some cool (but not unique) properties, but I wouldn't consider it "vital".

Of the 245 tonnes of platinum sold in 2010, 113 tonnes were used for vehicle emissions control devices (46%), 76 tonnes for jewelry (31%). The remaining 35.5 tonnes went to various other minor applications, such as investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.

250 tons per year is a tiny market in the world of commodities.

Catalyst converters for the autmotive marker, which is the main industrial application of platinum, are going to be phased out as petrol/gas engines are replaced by cleaner alternatives. This will drive prices down.

The appeal of platinum jewellery comes only from the rarity of it. If it was more common, you would reduce demand.

As for the other applications, once you remove the volumes are anecdotal with only a few tons per year. It isn't a consumable, so it is rare and expensive enough to be worth recycling.

Dump a 1000-ton asteroid on a decreasing 250-ton/year market, and you crash the price however you look at it. You can try to keep reserves and only inject small amounts on the market every year, but sitting on a pile of platinum is not going to make you rich, and it will take ages to recoup your exploitation cost.

You'd be better off investing in recycling old catalystic converters.

As for getting an asteroid on the ground, that would be a hugely risky business. Basically, its ability to survive reentry would depend on the structure and density of the asteroid. It might break up and explode into tiny chunks spread all over Kazakhstan, making the people of Kazakhstan rich and you very poor.

Edited July 28, 2015 by Nibb31

[Tex_NL]

Sure, adding a large amount of any valuable resource to the market will effect the price. We can pretty much all agree to that. Lets focus on actually getting it here.

Any object not properly designed to (re)enter earth's atmosphere at multiple kilometres per second will do three things: Heat up, break up and burn up. And they can do an enormous amount of damage. The Tunguska meteorite was believed to be in the order of about 60 metres. The Chelyabinsk meteor a few years ago was only 20 metres.

Both of them were practically just small pebbles. Any rock big enough to make mining it on earth economically viable has to be a lot bigger. Imagine the damage that could do if your trajectory is slightly off. The damages alone will probably cost you more than the rock is worth.

- - - Updated - - -

Isn't platinum also used in some automobile engines?

Not sure about the engine. But most modern cars do contain at least some platinum. It's used in the catalytic converter.

[PakledHostage]

sitting on a pile of platinum is not going to make you rich

It might satisfy one's dreams of emulating Smaug, however...

[tater]

True enough regarding debeers, I mean the primary notion of dribbling out supply. Pt is selling at ~US$30,600/kg right now. , the current Dragon can return what, 3000kg? That'd be 45 M$ in platinum. You'd need to look at the return costs vs other costs to see how worthwhile that is.

Edited July 29, 2015 by tater

[AngelLestat]

if you sit in that platinum pile, you can sale it at the rate you want..

Nibb, you really need to do some business related studies..

The problem with this idea, is that I imagine that nobody will allow it.

There is not accurate calculations on where it will fall or if it will break and cause more area damage (also harder to haverster)

Humanity always search ways how to prevent collisions with asteroids, it will be hard for a company try to do the opposite.

Also nobody is the owner of the asteroid in space, so when it fall, the first people who reach it will be the owners, depending the country mining rules.

[Shpaget]

Four words. Nuclear Salt Water Rocket.

Forget the puny DS4G thruster. This thing will get it to the surface via propulsive landing without much problem.

Wow, the specs of those things!!!

Anyway, with the recent development of inflatable heatshields, which I suppose would be cheap to manufacture and launch, it's reasonable to assume that in a not so distant future, it will be feasible to safely deorbit significant amounts of material.

As for the ownership. Whoever does the deorbit choses where it will land and has a head start to place recovery in position. I don't see a problem with that aspect.

Anyway, I'd say the iron in orbit is much more valuable metal than platinum on Earth, if you can have lots of it in orbit. The only reasonable way to construct large space stations and establish permanent space population is to have a large supply of iron already in orbit.

[shynung]

Wow, the specs of those things!!!

A fitting performance for what is essentially atomic squirt guns, don't you think? Not to mention it being hypergolic.

Anyway, I'd say the iron in orbit is much more valuable metal than platinum on Earth, if you can have lots of it in orbit.

Agreed. Stuff in space is expensive because it is in space; getting it off the earth is the expensive part.

[ChrisSpace]

As far as I know there are 3 ways to bring a mineral-rich asteroid to earth:

1 - Bring it down piece by piece

2 - Put it inside a space shuttle - type cargo bay, then land that

3 - Glue lots of parachutes onto the asteroid, and give it a quick deorbit burn

[Scotius]

In the early XIX century aluminium was considered very valuable. Not because of its rarity, but because of prohibitively high cost of purifying it. Napoleon was given a dinner set made of aluminium, and considered it a gift worthy of the emperor Some years later advances in chemistry led to development of electrolytical refinement and presto - price of aluminium plummeted while amount of it on the market rocketed up. Today aluminium is used everywhere - from canned drinks to airplanes. Who knows what platinum could be used for if it becomes abundant and cheap? And the same goes for other substances - like iridium.

Hoarding won't work. You can hoard something if there is only few sources of it, and you control enough of them to control the price. If you get a platinum rich asteroid into Earth's orbit and prove exploiting it is profitable, several other companies will start their own endeavor to squeeze money from the space. The very next day probably Best thing you can count on, is couple of years worth of headstart.

[lajoswinkler]

In the early XIX century aluminium was considered very valuable. Not because of its rarity, but because of prohibitively high cost of purifying it. Napoleon was given a dinner set made of aluminium, and considered it a gift worthy of the emperor Some years later advances in chemistry led to development of electrolytical refinement and presto - price of aluminium plummeted while amount of it on the market rocketed up. Today aluminium is used everywhere - from canned drinks to airplanes. Who knows what platinum could be used for if it becomes abundant and cheap? And the same goes for other substances - like iridium.

Hoarding won't work. You can hoard something if there is only few sources of it, and you control enough of them to control the price. If you get a platinum rich asteroid into Earth's orbit and prove exploiting it is profitable, several other companies will start their own endeavor to squeeze money from the space. The very next day probably Best thing you can count on, is couple of years worth of headstart.

Platinum will never become cheap as aluminium. The reason why aluminium can be cheap is its abundance and it was expensive because it used to be isolated by using reduction with alkali metals which are themselves very expensive. There is an enormous amount of aluminium in Earth's crust. Its mass fraction is a bit over 8.23 %.

Platinum's mass fraction in the crust is 0.000005 %, more than a million and a half times less. The price isn't going anywhere. It is fluctuating hourly by a small amount, which is governed by the stock market.

The price of platinum from space would not be any better because the expenses of the production process would be astronomical. In fact, I'm pretty much sure the price would be way larger.

Edited July 29, 2015 by lajoswinkler

[Streetwind]

Why would you want to bring the asteroid down to Earth? We have 2-3 companies now who are eyeing a much more practical approach: mining the asteroid in space - in solar orbit, to be precise - and only transferring down the refined material every couple of years when encountering the Earth again.

One of these companies, Planetary Resources, has stated that they are looking at low-density metal wool balls. Think steel wool, only made out of platinum. The drag on these things would be so high compared to their tiny weight that you could literally just toss them at the atmosphere and wait. With the right angle, they will slow down gradually without even warming up much. Then you only need to collect them wherever they happen to drop from the sky at the terminal velocity of a person on a parachute.

The big problem with this approach of course is the general unpredictability of Earth's atmosphere and high-altitude winds. If you want any hope of targeting them precisely, you need much better wheather monitoring and computational prediction. Thankfully, we have maybe another 10 or so years until asteroid mining really becomes a thing in earnest, and Moore's Law isn't yet showing signs of failing, so we might just have those models by the time they're needed.

Also, can we please get serious about nuclear salt water rockets for use inside Earth's atmosphere? That thing, if you haven't noticed, is an open cycle nuclear drive. That means it shoots highly radioactive nuclear material out the nozzle. You know full well that that's not acceptable. In deep space, sure - above the heads of living organisms, hell no.

Edited July 29, 2015 by Streetwind

[shynung]

One of these companies, Planetary Resources, has stated that they are looking at low-density metal wool balls. Think steel wool, only made out of platinum. The drag on these things would be so high compared to their tiny weight that you could literally just toss them at the atmosphere and wait. With the right angle, they will slow down gradually without even warming up much. Then you only need to collect them wherever they happen to drop from the sky at the terminal velocity of a person on a parachute.

I'm not sure a metal wool ball can reach the surface from past orbital velocity without disintegrating on the way down. Sure, they have high drag and low mass, but they don't have much structure other than tension.

Also, can we please get serious about nuclear salt water rockets for use inside Earth's atmosphere? That thing, if you haven't noticed, is an open cycle nuclear drive. That means it shoots highly radioactive nuclear material out the nozzle. You know full well that that's not acceptable. In deep space, sure - above the heads of living organisms, hell no.

Yes, it's open cycle nuclear. Yes, it does spew radioactive steam out the nozzle. Though, it's hard to say no to a ridiculously simple engine (compared to, say, solid core nuclear thermal engine) with a TWR comparable to lower-stage chemical engines (40), yet still manage 6728 seconds of I_sp while using 20% enriched uranium - 479000 seconds, if using 90% enriched/weapons grade uranium.

On a more serious note, there are people questioning whether we can build a practically usable ship that could survive turning the engine on. That, and it leaves glowing-blue craters whenever it lifts off from unprotected ground.

[SomeGuy12]

Yes, it's open cycle nuclear. Yes, it does spew radioactive steam out the nozzle. Though, it's hard to say no to a ridiculously simple engine (compared to, say, solid core nuclear thermal engine) with a TWR comparable to lower-stage chemical engines (40), yet still manage 6728 seconds of I_sp while using 20% enriched uranium - 479000 seconds, if using 90% enriched/weapons grade uranium.

On a more serious note, there are people questioning whether we can build a practically usable ship that could survive turning the engine on. That, and it leaves glowing-blue craters whenever it lifts off from unprotected ground.

It wouldn't be that simple an engine. The problem is, the nuclear reaction produces immense waste heat and neutrons. There's supposed to be this swirling layer of water to protect the inside of the engine bell. Except, that water will vaporize, and be lost, reducing your ISP. That 479000 number sounds impossible as a result of this - the water you'd lose would ruin your ISP. The 6.7k is marginal - NERVA engines could do 1k, and you have 36 times the power output by reacting the fuel directly without a heat exchanger. That sounds possible with a lot of engineering work. There would be a set of complex systems to cool the engine, probably using droplet radiators because they are immensely lighter.

Another issue is powered landings. Assuming you're trying to land on a vacuum moon, what do you do when you get near the surface of the Moon? Won't the exhaust reflected off the ground fry your engine and spacecraft? Maybe you could inject a lot of water into the exhaust right before touchdown, slashing your ISP but making the landing survivable.

That neutron flux is really annoying. There's no stopping the neutrons from the fission reaction from impinging on your engine and dumping waste heat into all the components. This is why I've been recently thinking that anuetronic fusion, if it can ever actually work, is a winner. Basic concept of the engine : the fuel is injected as plasma and the fusion happens in a continuous flow reaction, where the fuel stream passes through some honking big magnets and charged metal grids and is crushed with enough pressure to fuse. The exploding plasma then travels into the engine bell, which is immense, and is made of a latticework of magnet cables and empty spaces between them. The light from the reaction and many of the neutrons usually will pass through the gaps in the engine bell out to space. You also keep the neutron production down by this single-pass "flow" of fuel, where the reacting fuel only gets a chance to fuse once, so there are less side reactions.

The exploding plasma is allowed to expand in the middle of the engine bell, but the alpha particles and electron products are redirected with a variety of magnetic and electric fields away from the engine components and out the back instead.

In theory, almost none of the immense energy of the reaction actually heats up your engine, since none of the electrons or helium nuclei hit it, and you have all the components coated with a 99% reflective mirror material to reflect away light, and there are gaps in your engine bell that permit more than 50% of the light and neutrons to fly away into space instead of impinging.

In theory, this would let you jack the power output way, way up, possibly to sci-fi levels of thrust. (continuous burns of a decent fraction of a G - you would need terawatts of engine power to do this) Whether this is possible or not depends on things like how good you can really make your superconductors, whether we can get this fusion thing to actually work without needing a fission bomb to create the needed conditions, and so forth.

[Streetwind]

I'm not sure a metal wool ball can reach the surface from past orbital velocity without disintegrating on the way down. Sure, they have high drag and low mass, but they don't have much structure other than tension.

I'd love to give you a better reference for this than the claims of a company spokesperson in a stage presentation, but I'm on mobile right now and searching stuff and copying links is awful.

[SomeGuy12]

I'm not sure a metal wool ball can reach the surface from past orbital velocity without disintegrating on the way down. Sure, they have high drag and low mass, but they don't have much structure other than tension.

I believe it. SOme of the deorbited satellites, certain metal parts came down totally intact. Shape matters.