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Asteroid Mining by 'Planetary Resources'
Phil Stooke
post Apr 25 2012, 06:26 PM
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Impact in Western Australia? When there are so many other places just crying out to be obliterated? No, I prefer the idea of lunar orbit.


... because the Solar System ain't gonna map itself.
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post Apr 25 2012, 08:48 PM
Post #17

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Renting out a suitable target area could be a lucrative business for somebody - make everyone in Greenland a millionnaire perhaps??? Obviously there would have to be strict limits on chunk size and velocity. The timing of events would be known in advance so there would be time to fit earplugs and retire to a shelter for those not wanting to witness the impacts live.
(Come to think of it - there's another business opportunity. Impact tourism! Specially designed hotels with bomb-proof observation lounges. Even special vehicles for the most daring: you know, the sort of folks who just can't get close enough to a tornado . .)
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post Apr 25 2012, 10:52 PM
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Actually - smallish, metalic asteroids don't make for an easy entry - they tend to air-burst at a few km up.

If, say, a 10m iron asteroid was able to impact (7.5km/sec being the impact speed) you're talking about a 100x25m crater.

Or much bigger according to

A >10km/s impact is more likely - and that's more likely to air-burst.

http://simulator.down2earth.eu/ is also fun.

The lithbraking method of Earth arrival is not one I would recommend or support.

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post Apr 25 2012, 11:55 PM
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I very much doubt that PRI intends to return the entire asteroid to Earth -- for one thing, the energy costs alone would be enormous. They may or may not transport the asteroid to high lunar orbit, but in my non-expert opinion, the most cost-effective route would be to process the asteroid in situ using the abundant solar power to heat the material. A light-weight parabolic mirror could concentrate solar radiation into a solar furnace, with the focus capable of reaching almost the temperature of the surface of the sun, enough to vaporize any material.

One approach would be something like fractional vaporization, with the pulverized asteroidal material being brought to successively higher temperatures. The less refractory material, including all the bound volatiles, would be boiled off at the start, with successively higher boiling-point materials vaporizing as the temperature increases. If the sunlight is concentrated along a straight line, with increasing temperatures along its length, the metal vapor that is released at the boiling points of each of the metals that it would be worthwhile to transport back to Earth (the PGMs and Gold) could be collected by vapour deposition. The fact that this would be done in a vacuum should make this relatively easy.

Of course this process would be horribly inefficient of energy, but once the mirror is deployed, it's all free of charge. There's plenty of available energy there, it just needs to be collected.

Some numbers:

Element / Boiling Point / Concentration * / Current Spot Price per Troy Ounce / Current Value of Element in 1 Million Tonne Iron asteroid (~50m diameter)

Au / 3129K / 0.6 ppm / $1,642 / $31.678 million
Pd / 3236K / 1.2 ppm / $662 / $25.543 million
Rh / 3968K / 8.6 ppm / $1,385 / $382.990 million
Pt / 4098K / 63.8 ppm / $1,552 / $3183.846 million
Ru / 4423K / 45.9 ppm / $115 / $169.727 million
Ir / 4701K / 31.0 ppm / $1,085 / $1081.511 million
Os / 5285K / 31.3 ppm / $380 / $382.444 million
Re / 5869K / 2.4 ppm / $143 / $11.035 million

Each ppm equals one tonne of the metal in a 1 million tonne asteroid.

The total value at current spot prices would be $5269.774 million, and the mass would be just under 185 tonnes, much easier to transport to Earth than 1 million tonnes! Of course the prices would be a lot lower with these quantities of PGMs available -- which would be all to the good in my opinion, these metals are very useful in various applications, but are heavily limited by their cost.

Of course other metals might be valuable enough to refine and transport to Earth as well. For example, pure Germanium metal is currently selling for $1275/Kg, so that would be another $44.625 million from a million-tonne 98 % Fe asteroid, and a whopping $1300 million from an LL Chondrite asteroid of the same mass. There may be other metals that would be worth extracting as well.

* The Role of Near-Earth Asteroids in Long-Term Platinum Supply

Where "98th % Fe" means that the results are for the 98th percentile iron meteorite, ranked by PGM content.

Actually, even an ordinary Chondritic asteroid (much more common) massing 1 million tonnes has about half the value** in PGMs and Gold of the rarer high-end Iron asteroid (plus as I said above, $1300 million worth of Germanium). So maybe just about ANY Iron or Chondritic asteroid would do!

** The reason being that on Earth, almost all the PGMs, being almost inert chemically, sank to the earth's core during its differentiation, so the Earth's crust is heavily depleted compared to the undifferentiated Chondritic asteroids, much less the PGM-enhanced iron cores of the differentiated but now disrupted asteroids.
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post Oct 18 2014, 10:19 AM
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Planetary Resources' first small space telescope to fly later this month

I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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