Mining an Asteroid

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We could perhaps bring a 0.2 kilometer iron asteroid into circular Earth orbit with a radius of about 300,000 kilometers for 20 billion dollars. V = 4/3 3.1416 r cubed. = 4,100,000 cubic meters = 25,000,000 metric tons. the ten times bigger would have a mass of about 25 billion metric tons. If we attach enough rocket engines to produce a thrust of 25,000 metric tons = 55 million pounds, we can accelerate the small asteroid at 0.001 g the larger one at one millionth of a g. The one thousandth of a g might be sufficient to do a sling shot maneuver around Earth's moon, that might produce the approximately circular Earth orbit. We can then refuel the rocket motors for future orbit corrections when the asteroid comes significantly into the moon's gravity field several times per decade. We need lots more energy to get the asteroid into a closer circular orbit which will be more stable.
If we mess up the asteroid could total a very large Earth city, so there will be a lack of public enthusiasm. We can remove chunks of the asteroid and deliver it to Earth for about $50,000 per pound. Any metals in the asteroid worth that much money are likely mixed with millions of times as much low value stuff, so we need to build a separation facility on the asteroid or forget about sending very valuable metals to Earth. We can instead refine more common metals and fabricate space craft, nuclear power plants etc on the asteroid, but this means creating a vast infrastructure on the asteroid at a cost of trillions of dollars, unless we get some break thoughs in technology. Also the asteroid has too little surface area to accommodate a vast infrastructure easily. We will be building 100 story buildings on the asteroid. Please correct, embellish and/or refute. Neil

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Mining asteroids is a good idea, especially since our terrestrial resources are being used up. It would also serve to help us develop space travel. Where are you getting these cost estimates from?

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Mining asteroids absolutely MUST happen.
The rewards of doing so are greater than can really be imagined. Not to mention that once you've finished hollowing out the interior you can use the thing for storage space. For what ? Well how about several million humans for a start.

Initially the easiest and cheapest way to go about it is to send out a couple of ion engines and attach them remotely to a suitable asteroid. Not too big an asteroid, just a few hundred meters in diameter will do for starters.
The ion engines are cheap and if one sends them out to the asteroid belt by a longer and more roundabout route allowing the craft(s) to gain a bit more energy then you can save a great deal of cash by using a smaller booster.
You could send out quite a few craft with the ion engines to attach them to a few floating mountains.
It might take 20 years to get the first one on a heading for Earth but once it's started it is inevitable.
Placing one into Earth orbit is simplicity itself and by this time it may be easier to insert them into a lunar orbit instead to save any possibility of one accidentally crashing into my house.

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Why don't we intentionally crash the asteroids onto someplace convenient and then mine it from down here (where it's cheaper). We can control the velocity for entry, and we can choose the size of the rock, so it should be relatively safe.

If we need a hollow one in orbit somewhere, then we will want to leave it orbiting something while we hollow it out (rather than crashing it of course).

What if someone finds gold on an asteroid. How long do you think it would take for someone to figure out how to get it. The next gold rush could be in the space frontier. Smile

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rosborne979 wrote:

Why don't we intentionally crash the asteroids onto someplace convenient and then mine it from down here (where it's cheaper).

Our goal should be to develop effective space travel and propagate mankind out among the stars. Trying to bring everything back to Earth seems to be working in the opposite direction. It would serve to develop our space flight capabilities much more, to be able to work in space.

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If you chose the right target initially you would only have to do it once. Then you use the hollow shell to make a craft that could head back out to the asteroid belt and mine on location. Given the timeframes involved we should have the technology to do it by the time the craft is ready.

As an aside what would you think the long term ramifications are of depositing millions and millions of tons of extraterrestrial matter onto the planet. Geologically and gravitationally.

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Your average asteroid contains trillions upon trillions of dollars of iron, nickel, etc.

No doubt companies are spending fortunes right now trying to figure out how to do it.

The first person to get up there would make a killing.

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rosborne979 wrote:

Why don't we intentionally crash the asteroids onto someplace convenient and then mine it from down here (where it's cheaper). We can control the velocity for entry, and we can choose the size of the rock, so it should be relatively safe.

You honestly really can't control the velocity of an asteroid too much. The amount of inertia is really amazing. Plus you'd be fighting the gravitational field of the body you're crashing them into.
Even the Moon with a g of only 1.6m/s^2 will accelerate asteroids to unmanagable velocities even if you did make it crawl into orbit.
So basically when they hit, they vaporise and the amount of local destruction, ejecta, cratering etc... etc... would make it unacceptable anyway. No point in crashing them anywhere

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Plus if you missed land and hit the water then that'd be a really big oops.

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Heliotrope wrote:

You honestly really can't control the velocity of an asteroid too much. The amount of inertia is really amazing. Plus you'd be fighting the gravitational field of the body you're crashing them into.
Even the Moon with a g of only 1.6m/s^2 will accelerate asteroids to unmanagable velocities even if you did make it crawl into orbit.
So basically when they hit, they vaporise and the amount of local destruction, ejecta, cratering etc... etc... would make it unacceptable anyway. No point in crashing them anywhere

If this is the case, then how are you going to get the material you mine from the asteroid back to Earth to use it? You have the same problem de-orbiting a ten ton asteroid as you do de-orbiting ten tons of mined material.

And if you say we can drop smaller loads, then I say find smaller asteroids. It's all the same problem gravitationally. The question is, where is it more economically efficient to do your mining, Earth or Space?

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Brandon9000 wrote:

Our goal should be to develop effective space travel and propagate mankind out among the stars. Trying to bring everything back to Earth seems to be working in the opposite direction. It would serve to develop our space flight capabilities much more, to be able to work in space.

I think I agree with this. So you're not saying we should bring stuff back to Earth at all, just use the raw materials to build things in space, to be used in space.

The net effect of this on Earth would be that humans and space vehicles would flow away from the planet. As a result the planet gains knowledge (assuming we remain in contact with the space colonists even thougth they will become self sufficient), and maybe some small valuable pieces of material, but the planet will not accumulate much bulk material.

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rosborne979 wrote:

If this is the case, then how are you going to get the material you mine from the asteroid back to Earth to use it? You have the same problem de-orbiting a ten ton asteroid as you do de-orbiting ten tons of mined material.

Ahhh, right.
Ok, a couple of points to clear up some things.
A cubic meter of rock weighs roughly between 2 tons and 4 tons so a 10 ton rock is only going to be a couple of cubic meters or about the size of the box that you could get your sofa into. Basically very small rocks.
Asteroids don't really come in the 10 cubic meter range. At those sort of sizes they're really just floating rocks. You can easily drop them where you like with only a relatively small amount of localised destruction and a lot of them will vanish in the atmosphere due to the heat of entry anyway unless you have a certain density and then you'll just have an explosion.

The other problem with the really small ones is that you'd need rather a lot of them to make any sort of economies of scale. A typical opencast mine removes several thousand cubic meters, and some a lot more, of material every single day so to even match this the amount on 10 cubic meter rocks pouring into the atmosphere would heat it up to an unacceptable level over time. Not to mention the extra dust etc... floating around playing havoc with the environment, weather patterns and the heating and cooling cycles.
So basically mining small rocks is not practicable.

For your other point about getting the meterial down to Earth, well why would you want to ?
Why do we need more rock down here ?
We don't.
What we DO need are refined metals, silicates and hydrocarbons.
These can all be sent down without the problems of having a few thousand rocks falling onto the planet every day.
You get, firstly, a big asteroid - a couple of hundred meters across as I said earlier. You hollow it out, extracting the hydrocarbons and metals as you go and refining them in orbital facilities from where they are sent down to Earth, then you use most of the crushed rock to make the asteroid air tight and then fill it full of volatiles, water, oxygen etc... gathered from other asteroids such as carbonaceous chondrites and then use what's left of the rock to make buildings and infrastructure.
In fact most of the material you've mined will have to go back into construction of the orbital facilities and turning the asteroid into somewhere to live and work. There will be a lot of stuff that can come down to Earth though.

How much do you think a couple of cubic meters of nickel costs ? Or palladium ?

Lots and lots of money.
All free.

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Oh and the size I mentioned there is only a couple of hundred meters.
This is just for starters.
After that they need to get big and I mean several tens of kilometers big.
THAT's when the cash will start to roll in.

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As far as getting the refined materials out of orbit, I think the two most promising options are either a tether or laser beams. Both require a fair bit of technological advancement before they would work, but they are theoretically feasible. I think Neil has already started a thread about tethers a while back. If you used lasers to bring down metals you wouldn't need to completely control the descent. You could pick a desert somewhere and allow the stuff to just fall using the lasers only to slow it down enough to not melt or make massive craters.

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Heliotrope wrote:

Ahhh, right.
Ok, a couple of points to clear up some things.
A cubic meter of rock weighs roughly between 2 tons and 4 tons so a 10 ton rock is only going to be a couple of cubic meters or about the size of the box that you could get your sofa into....

The size of the payload doesn't matter, but its mass does.

To simplify the problem we can recognize the it will cost the same in effort and dollars to get x tons of rock to the surface as it will to get x tons of palladium to the surface.

As you say, the mass of the palladium will be less than the rock which yielded it, so the problem becomes figuring out whether it's cheaper/easier to get things de-orbited, or whether it's cheaper/easier to mine in space. I guess I don't know the answer to this. Do you?

The other benefit to doing things in space is that we gain experience in working in that environment, and many of the materials don't even have to come back to Earth (even though returning them to Earth was the supposition of Neil's original post, and to which I directed my reply).

So yes, I agree with the idea of harvesting asteroids in space, but not for the goal of bringing loads of stuff back to earth, but for the rewards we get from beginning to colonize space. I don't think of this process as "mining", I think of it as colonization, just as setting up colonies in the early Americas was not "mining" of America, but colonization.

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Adrian wrote:

As an aside what would you think the long term ramifications are of depositing millions and millions of tons of extraterrestrial matter onto the planet. Geologically and gravitationally.

If large scale space travel were common, we might bring matter from space to the Earth or send matter from the Eath into space. I wonder if we might not eventually change the Earth's mass enough to affect its orbit. That would, or course, require a collosal addition or loss of matter. This might be something that could happen if a trend continued for a long time. I don't think this is very likely, since such a huge change would be required to produce even the tiniest effect, but we should be careful not to do it.

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So now that we've decided that it's a good learning experience, and good colonization practice to mine asteroids, how do we get it to happen. Or more to the point, if it's a good idea, why isn't it happening already?

Many people feel that space science is a boondoggle already, so it's hard to get funding. Also, the up front funding is going to be very steep since we have to invent everything for the first time.

In order to get something like this going, we need to have some type of economic return which is fairly immediate, and I don't know what that would be.

Actually, before I would start trying to mine asteroids for colonization and long term space travel, I would start with making a larger space station so we can practice building, and so we have a launch platform to move out from. Then I would head to the Moon and try to build a base there. The moon will have at least as many resources as a common asteroid, and is much closer. Then I would move from the Moon to Mars to practice more building and living, and to get another base of operations which is much closer to the asteroids we might want to mine. THEN I might try to mine an asteroid... unless of course, that by the time we get there, the whole game hasn't changed in some way due to what we learned getting there. Smile

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rosborne979 wrote:

So now that we've decided that it's a good learning experience, and good colonization practice to mine asteroids, how do we get it to happen. Or more to the point, if it's a good idea, why isn't it happening already?

Well, if I'm not mistaken, NASA has been given instructions to begin a program for a permanent moon base, although it is not on a very rapid schedule. The reason why this is all so slow to happen, is that it would have to be implemented by Congress, and the sort of person who tends to get elected is not the sort of person who is likely to pass bills which require foresight, and give mostly ultra long term benefits.

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Brandon9000 wrote:

...and the sort of person who tends to get elected is not the sort of person who is likely to pass bills which require foresight, and give mostly ultra long term benefits.

You have no idea of how much this angers me.

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Heliotrope wrote:

Brandon9000 wrote:
...and the sort of person who tends to get elected is not the sort of person who is likely to pass bills which require foresight, and give mostly ultra long term benefits.

You have no idea of how much this angers me.

Unfortunately, I suspect that people with our viewpoint on things represent a minority of the population. We need to learn to persuade others better, or reproduce faster Wink

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Mining an Asteroid

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