Total Members Voted: 121
Please advise how to move ore cheaply.
Quote from: JohnFornaro on 05/01/2012 01:05 pmdealing with those quantities of loose slag, without the handy effects of a large gravity well underneath them, still need to be solved, and you have not suggested any solutions to that problem.Probably because there are many ways to do it, some of which are dependent on the metals fractionation process decision and composition. Sintering into bricks, collecting in bags, are among options. They might even be collected by Jon Goff's stickyboom. etc.
dealing with those quantities of loose slag, without the handy effects of a large gravity well underneath them, still need to be solved, and you have not suggested any solutions to that problem.
Mining at the expected scale has not taken place except within the Earth's gravity well. It will be interesting to find out how they plan to do it.
Quote from: Robotbeat on 05/01/2012 03:08 pmReally, if you can get a metric ton of pure PGM, you've already won the war. I disagree with your premise. The other parts are going to be harder. Transportation costs are just easier to quantify (which is why we focus so much on them).Please advise how to move ore cheaply.
Really, if you can get a metric ton of pure PGM, you've already won the war. I disagree with your premise. The other parts are going to be harder. Transportation costs are just easier to quantify (which is why we focus so much on them).
Quote from: Danderman on 05/01/2012 03:14 pmQuote from: Robotbeat on 05/01/2012 03:08 pmReally, if you can get a metric ton of pure PGM, you've already won the war. I disagree with your premise. The other parts are going to be harder. Transportation costs are just easier to quantify (which is why we focus so much on them).Please advise how to move ore cheaply.SEP, for one. Or chemical, using ISRU propellant.But anyway, those are just guesses. My real point is that extracting the ore is probably more difficult and we have less understanding of that part.
I voted asteroid.A single SEP tug (~20 tonnes fueled in LEO) could capture a 1000 tonne carbonaceous chondrite asteroid into high lunar orbit. 20% of that mass could then be extracted as water, simply by heating, which is not particularly complex given continuous sunlight. Lets guess another 20 tonnes in LEO for the ISRU plant. 40 tonnes in LEO gives at best 20 tonnes of useful payload at L2. From a pure mass in LEO perspective asteroid mining breaks even when 20 tonnes is extracted in cis-lunar space.
Taking into account tug and ISRU plant development, extraction of about 50 tonnes of useful stuff (e.g. water) is needed to break even financially.
In contrast lunar mining is much less defined.
The Lunar environment seems less hospitable to mining as well. The best deposits seem to be in permanently shaded craters, which complicates water extraction. Lunar dust is very abrasive. A four week day night cycle gives great temperature extremes and makes use of solar power difficult.
Any products of ISRU are at the bottom of a gravity well. OK, its only Lunar gravity, but that still adds to the cost, at best it doubles the cost and probably more like 3x or 4x the cost for resources delivered to L2.
Quote from: MikeAtkinson on 04/30/2012 07:17 pmI voted asteroid.A single SEP tug (~20 tonnes fueled in LEO) could capture a 1000 tonne carbonaceous chondrite asteroid into high lunar orbit. 20% of that mass could then be extracted as water, simply by heating, which is not particularly complex given continuous sunlight. Lets guess another 20 tonnes in LEO for the ISRU plant. 40 tonnes in LEO gives at best 20 tonnes of useful payload at L2. From a pure mass in LEO perspective asteroid mining breaks even when 20 tonnes is extracted in cis-lunar space.I am skeptical that SEP will provide the magic bullet that its boosters seem to think it represents. The problem is I don't see how it scales well. E.g., moving 1,000 mT with 20 mT propellant. What is everything? What is the Isp?What is the delta v?What is the trust-weight ratio?What is the propellant?What is wattage?What is the area of the solar array?What is the dry mass?What is the plan to deal with the torques that come with trying to rotate, and then stop rotating a 1 to 4 square kilometer array? ...
The orbital refinery is somewhat necessary for lunar mining.
Once the depot exists at EML1/2, one then brings power, personnel, refining equipment to EML1/2, and then...drops it down into the gravity well? And then builds a refinery in a gravity well?
Quote from: MikeAtkinson on 04/30/2012 07:17 pmThe Lunar environment seems less hospitable to mining as well. The best deposits seem to be in permanently shaded craters, which complicates water extraction. Lunar dust is very abrasive. A four week day night cycle gives great temperature extremes and makes use of solar power difficult.This reflects an unfortunately typical misunderstanding of the Lunar ice deposits. Granted, the permashaded craters are among the coldest places in the solar system, but we already have materials in hand that can handle it, like certain nickel-iron alloys made by Inconel and Incolloy.
Moreover, in the polar regions, the temperature extremes are pretty mild. There are quasi-permanently plateaus in the polar regions that are illuminated 80% of the time or more. There the temperature stays a relatively balmy minus 50 degrees, plus or minus 10, all year round.
As for Lunar dust being abrasive, (a) that's no different from the dust that results from hard rock mining operations on Earth;
(b) there's no reason to think that asteroidal dust is any less abrasive.
Asteroids (51% chance or better) 25 (43.1%)The Moon (51% chance or better) 10 (17.2%)Neither 4 (6.9%)It's a coin flip (50% chance for both) 19 (32.8%)Total Voters: 58
I voted Moon, because the robotic, zero-g manipulation of materials which would be needed to create (non-token) quantities of anything from asteroids seems difficult to engineer. Gravity is apparently under-rated among NSF forum contributors!
My real point is that extracting the ore is probably more difficult and we have less understanding of that part.
1. My understanding is, on Earth, all the heavy metals were drawn to the core while the planet was still molten. What we mine on the surface was deposited by asteroids and comets after the crust hardened. I assume the same thing happened on the Moon. Might as well get the good stuff from the source.
Companion moons are a common outcome of simulations of Moon formation from a protolunar disk resulting from a giant impact, and although most coplanar configurations are unstable, a ~1,200-km-diameter moon located at one of the Trojan points could be dynamically stable for tens of millions of years after the giant impact. Most of the Moon’s magma ocean would solidify on this timescale, whereas the companion moon would evolve more quickly into a crust and a solid mantle derived from similar disk material, and would presumably have little or no core. Its likely fate would be to collide with the Moon at ~2–3 km s−1, well below the speed of sound in silicates. According to our simulations, a large moon/Moon size ratio (~0.3) and a subsonic impact velocity lead to an accretionary pile rather than a crater, contributing a hemispheric layer of extent and thickness consistent with the dimensions of the farside highlands.
2. Much less gravity well to soak up profit.
Rooting for both to succeed however!
The Moon has concentration mechanisms that don't exist on asteroids. The phenomenon whereby volatiles are concentrated in the polar cold traps is well known... As the LCROSS results showed, there is also water in the polar cold traps.
But these are not the places where the ice is are they? Sun-lit plateaus are not permanently shaded craters, some are within 10km of each other I believe.
Quote from: Warren Platts on 05/01/2012 06:50 pmAs for Lunar dust being abrasive, (a) that's no different from the dust that results from hard rock mining operations on Earth; Every serious study I've seen says lunar dust is almost uniquely abrasive and point to dust mitigation being a significant problem.
Quote from: Warren Platts on 05/01/2012 06:50 pm(b) there's no reason to think that asteroidal dust is any less abrasive. Yes, there is, we have samples, Carbonaceous Chondrites are much softer and less abrasive than lunar dust.
1. My understanding is, on Earth, all the heavy metals were drawn to the core while the planet was still molten. What we mine on the surface was deposited by asteroids and comets after the crust hardened.