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Heat-shielded Asteroid Platinum Mine

Bringing the goods home
 
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So, an estimated 17% of asteroids in the solar system are 'S-type,' which means they are made of iron, nickel, and liberal dashes of other valuable metals, including, quite possibly, diamonds and platinum. Another 8% or so are metallic 'M-type' asteroids, and also full of desirable elements. Many ofThese things have prices in the trillion dollar range. 3554 Amun, a 2.5 km radius M-type asteroid, has a twenty trillion dollar price tag. (More than the GDP of America, to give a point of reference.) So, anybody who figured out how to mine Amun would be doing very, very well for themselves.

Asteroid mining is hard. Asteroids are far away, and they move fast. Mining might not be so tricky, what with the zero-gravity and all, but getting mining equipment out there-- and having it be capable of sending precious ore back to earth-- is tricky. What would be much easier is to take the asteroid and bring the whole thing to Earth.

First, shoot some explosives at your chosen asteroid. Have them detonate in the asteroid's path, so that the asteroid slows down. But be careful-- don't set them off too close or you'll break your asteroid. The asteroids you'll want to mine will be pretty big, so you'll need to have it moving as slowly as possible before you bring it back to Earth. Next, send robots-- or maybe even a manned crew, if necessary-- to meet up with a nearby asteroid. Plenty of the valuable ones intercept Earth orbit, so going all the way to the asteroid belt is probably unnecessary. The purpose of this mission will be to blanket the asteroid in a heat-shielding material, like the tiles on the outside of the space shuttle. These tiles aren't heavy. They're almost like foam. Getting enough of them into space shouldn't be too hard. Covering the asteroid with these tiles could be done by hand by a crew (which would take a while) or via some sort of unrolling process (the tiles are placed in a roll on the asteroid and unroll across its surface) or even by adhesion (just shoot enough sticky tiles at the asteroid until it is covered). Once that's done, start detonating explosives again to nudge it towards Earth. You may want to attach some rockets for greater precision.

Impact is going to be a problem. These things are large, and even if you brought a small asteroid to Earth, and landed it in an uninhabited area, the shock wave will be enormous, which is why slowing it down with explosives is so important. Also, it'll need to approach the Earth at an angle, so as to achieve aerobraking for as long as possible. The heat shield will prevent any of the valuable metals from being lost, and stop the asteroid from breaking up. Aim it so that it lands in, say, a large desert or maybe salt flats, so no one will be harmed by impact and fragments of the asteroid will be easy to find (because, heat-shielded or not, this thing will explode when it hits the ground). You'll want to monitor the impact from satellites, to keep track of where all the fragments end up. They should still be pretty large and easy to find, but try not to lose any.

And now, all the nickel, iron, platinum, and diamonds are yours, and within easy reach. Mine it. If all goes well, you'll soon be buying small nations on a daily basis. Remember, however many billions of dollars you spend on building the spaceships to bring the asteroid here, it won't be a dent on your profit margin when you're rolling in space platinum.

moustache_mcflanigan, Feb 22 2010

Riches in the Sky http://www.associat...steroid.html?cat=58
Article detailing some of the information about types and values of asteroids [moustache_mcflanigan, Feb 22 2010]

10 billion trillion trillion carat diamond http://www.theage.c.../1076779937571.html
Yours for the low, low price of a one hundred light year round trip. [2 fries shy of a happy meal, Feb 23 2010]

[link]






       You'll pretty much wipe out life on Earth and bring about a new ice age, but on the plus side, you'll have trillions of dollars worth of platinum.

How much explosive will an asteroid need to slow it down? If an asteroid is a cubic kilometre of rock with (to make the calculations easier) the same density as water, it has a volume of 1x10^9 m^3 and weighs 1x10^12 kg. If it is travelling at, say, 10 km/s it has a kinetic energy (given by 0.5mv^2) of 0.5x10^20 joules.

You'll need a similar energy to stop it. If we assume (optimistically) that we can harness half the energy of our explosions to slow down the asteroid, we'll need 1x10^20 joules of explosive energy, or the equivalent of 23900 megatons of TNT (using a joules-to-megatons converter I found on the internet). So, in round numbers, 24,000 Hiroshima-sized nuclear bombs.
hippo, Feb 22 2010
  

       Wipe out life on Earth? Heavens, no. Meteor Crater in Arizona was formed by something like this, and while that was a hell of a bang, it didn't destroy life on Earth any more than a nuclear bomb would. Also, that crater was formed by an object moving hellishly fast, as our asteroid mine hopefully wouldn't be. If the asteroid is any larger than a square kilometer or two, it would be wise to break it up before heat-shielding, but still, just drop it in the Australian outback or somewhere similar and hardly anyone will notice. Okay, they'll notice, but they won't die.   

       Regarding the 23,900 megatons: yeah, you're right. that is definitely a problem. however, if the profit is in the multi- trillion dollar range, why not? sure, there's an international ban on nukes in space (for good reason) but when that much money is on the line, bans could be lifted. The process might take years, but the payoff would be just as good.   

       Unless the constant nuclear blasts made the metal so badly contaminated with radiation that it was unusable, which would be unfortunate.
moustache_mcflanigan, Feb 22 2010
  

       Also, come to think of it, if you were really patient, you could have other ways of generating the 23,900 megatons. solar sails, for example. now we're talking about a project that would probably take centuries to complete, but it's a hell of a nest egg.
moustache_mcflanigan, Feb 22 2010
  

       I think using explosives to bring the asteroid into Earth's orbit is overkill. The smart alternative (admittedly requiring some patience) would be attaching a solar sail to the asteroid and navigating it through some complicated orbits (gravity assist, slingshot effect, Hohmann transfer orbit etc).   

       The asteroid is currently orbiting the sun. We want to bring it into Earth's orbit. The amount of energy needed to bring it into Earth's orbit is much less than the energy required to stop it in its tracks. The asteroid's energy needs to be converted: PE+KE -> PE'+KE'±extra energy. For example, by increasing PE to PE' and decreasing KE to KE', the amount of extra energy needed can be minimized.
xaviergisz, Feb 22 2010
  

       The cheap approach to asteroid mining would be to use small explosions to alter the trajectory of asteroids. With a number of these interventions, you make two similarly-sized asteroids collide head-on into each other. If they are travelling at similar speeds, this will produce a more-or-less stationary cloud of debris which can be easily mined.
hippo, Feb 22 2010
  

       No disrespect to Australia. We'll be careful, I promise.   

       //The amount of energy needed to bring it into Earth's orbit is much less than the energy required to stop it in its tracks.// Asteroids move crazy fast. When meteors hit Earth, they're mostly moving above 10 km/sec (thanks, Wikipedia). A big asteroid is going to kill some people at that speed wherever you put it. To avoid that, you'll want to be as gentle as you can, so it will need to be slowed down considerably.
moustache_mcflanigan, Feb 22 2010
  

       The Earth is orbiting around the sun at about 30km/sec. As long as you choose an asteroid that's going in our direction (as most are, I think), it could be easier (i.e. energy-wise) than you might think.
xaviergisz, Feb 22 2010
  

       attract idiot investors, never do anything, draw a hefty salary.
WcW, Feb 22 2010
  

       Of course adding that quantity of iron, platinum etc into the economy will cause the prices to drop, so you won't make as much money as a naive estimate would suggest.
Wrongfellow, Feb 22 2010
  

       //3554 Amun, a 2.5 km radius M-type asteroid, has a twenty trillion dollar price tag.//
You can read it from here?

//Meteor Crater in Arizona was formed by something like this// "Like" in the sense of "a small scale model" - the asteroid there was "only" 50 metres across.
coprocephalous, Feb 22 2010
  

       If we seriously start asteroid mining, the metal value will be what it's useful for, not as cash. Admittedly Platinum and Gold have significant utility value as well as scarcity value, so it's not the worst idea. Diamonds are not worth anything near their current price, so ignore them (don't believe me? try reselling one, if "Diamonds are forever" why don't they maintain value)   

       Far better idea to refine in flight and in orbit. Splash down individual loads behind a silicon/ceramic or worst case ablative iron heat shield in shallow water off shore.
MechE, Feb 22 2010
  

       Maybe a suitable ablative shield could be made from the slag left over from the refining process?
Wrongfellow, Feb 22 2010
  

       If we crashed these things into the moon, it should avoid all that nasty megatonnage and leave lots of tiny bits spread out over the "dark side" of the moon (best not to spoil our view of the moon if we can help it) that a teem of robots could scour over simply picking up the best bits.
zen_tom, Feb 22 2010
  

       //First, shoot some explosives at your chosen asteroid. Have them detonate in the asteroid's path, so that the asteroid slows down.//   

       Bad science, right there.   

       //The purpose of this mission will be to blanket the asteroid in a heat-shielding material//   

       Then more bad science. Besides, all these metals would be worth a thousand times more in Earth orbit.
ldischler, Feb 22 2010
  

       hmm... given that lots of asteroids are nickle-iron wouldn't you think it'd be in NASA's best interest to fund Edison battery improvements ? </random'ish>
FlyingToaster, Feb 22 2010
  

       Zen-tom is right. It needs to be the moon. Here is how.   

       1: Blow it up real good. 2: Do spectral analysis of blowed up bits during the blowing up to find out which are best as regards juicy elements. 3: Go to those bits. 4: Redirect them to the moon, preferably by attaching fusion powered rockets that use nonvaluable asteroid junk as propulsive mass. 5: Find them on the moon. 6: Mine them on the moon. 7: Deliver refined metal to earth via railgun as per Heinlein.
bungston, Feb 22 2010
  

       //If we crashed these things into the moon// True, no innocent bystanders on the moon. But then you've got to build landing craft, go through all the difficulty of mining in a gravity field (without the convenience of doing it on earth) and build a system which can launch the heavy ore back to Earth. Why go through all the effort of harnessing an asteroid if you're just going to put it down somewhere else?   

       //Maybe a suitable ablative shield could be made from the slag left over from the refining process?// Actually, that's a very interesting idea.   

       //Besides, all these metals would be worth a thousand times more in Earth orbit.// Only for building more spaceships. Sure, leave some ore parked in near-Earth orbit if you want, but I want my platinum down here where I can get my own hands on it.
moustache_mcflanigan, Feb 22 2010
  

       //First, shoot some explosives at your chosen asteroid. Have them detonate in the asteroid's path, so that the asteroid slows down.//   

       I agree.   

       If you're happy to sacrifice some of the asteroid, it'd be better to have a device on the asteroid that takes chunks out of the asteroid and propels them in the opposite direction you want it to go. For example a slingshot type device that takes a chunk of asteroid, spins it at high velocity, then releases it.   

       //The purpose of this mission will be to blanket the asteroid in a heat-shielding material//   

       I think ld means that you need a nicely shaped/balanced object before you can consider putting heat shielding on it. Shaping the asteroid would be the other purpose of taking chunks out of it for propulsion.
xaviergisz, Feb 23 2010
  

       //Why go through all the effort of harnessing an asteroid if you're just going to put it down somewhere else?//   

       The heat generated from imapct should do a fair bit of the refining.
hmmm, could repeated impacts on the lunar dark side help to keep the Earth from eventually losing it as a satelite?
  

       //Deliver refined metal to earth via railgun as per Heinlein//   

       The metals would be much more valuable in space I would think, if you factor in the cost of getting them back up there if they are refined down here.   

       //collide head-on into each other. If they are travelling at similar speeds, this will produce a more-or-less stationary cloud of debris which can be easily mined//   

       Does anyone know if something like this has been tried with the orbiting space debris?
Could objects in low Earth orbit be nudged higher from the surface by lasers to collide with oposing trash, or do the odds against collisions make it a stupid idea?
  

       //collide head-on into each other. If they are travelling at similar speeds, this will produce a more-or-less stationary cloud of debris which can be easily mined//   

       I wonder to what extent the collision would be elastic and what extent inelastic? I don't think it would result in a //more-or-less stationary cloud of debris// though.
xaviergisz, Feb 23 2010
  

       Use your bombs, spaceships, and fearless crew to extort riches from others on Earth.
rcarty, Feb 23 2010
  

       I had to read this twice to fully grasp the oddnesses in it.   

       First, unconfined explosives are a big waste of energy. Second, explosives do not have the oomph-per-ounce of rocket fuels. Third, un-shielded descent through the atmosphere would be a good way to burn off all the unwanted crud from a mostly-metallic meteor. Fourth, any insulation would be completely destroyed on impact, and do diddly to protect the metal from shattering, and from secondary fragmental flights through the fireball.
baconbrain, Feb 23 2010
  

       //First, unconfined explosives are a big waste of energy.//   

       Good point. Whether rockets or explosives are used, though, it's going to be tricky getting them out there.   

       //un-shielded descent through the atmosphere would be a good way to burn off all the unwanted crud from a mostly- metallic meteor. //   

       I'm not risking losing any of my payload. Besides, even with big asteroids, there's the risk that it'll explode before it hits the ground, and then it would mostly be lost. That's the main point of the heat shield. But if it explodes on impact, that's okay, because the metal shouldn't actually vaporize. We'll just run around in the desert picking up all the pieces.
moustache_mcflanigan, Feb 23 2010
  
      
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