Author Topic: Gold Moon - Thread 2 - Numerical Simulation Results  (Read 20310 times)

Offline Warren Platts

That other thread was getting too long, and I want to present some new quantitative results here.

First off is an analysis of Gladstone et al.'s (2010) "LRO-LAMP Observations of the LCROSS Impact Plume", Science 330, 472. In their Table 1, they reported a 2-sigma upper limit of 1.6%; this was later lowered in an erratum by a factor of 5.47 to 0.3% (or 3 ppt).

Now, does this mean that they detected any gold? Or is NASA scientist Geoffrey Landis' assessment correct?:

Quote from: Landis
"Pay attention to that phrase: "UPPER LIMIT".  The lower limit is zero. In other words, they didn't find any gold, to within their (relatively poor) detection limits. ... Here is what is important: They did not report finding gold."

However, one can apply the error function (erf) to calculate the most likely value, based on the information provided. Erf(a/σ21/2) gives the probability that the true value is less than a. Since 2 sigmas is 3 ppt, then σ = 1.5 ppt. Thus,

erf(1/(1.5 * sqrt(2))) = 0.5

In other words, the most likely value is 1 ppt.

This is still a huge concentration, virtually unheard of on Earth. BTW the 2σ lower limit is 0.1 ppt or 100 ppm. In other words, according to Gladstone's analysis, there is a 95% chance that the true gold concentration is higher than 100 ppm (a.k.a. 100 g/t--grams per tonne in mining parlance). Note that on Planet Earth 100 g/t is considered to be a very rich ore indeed!

Bottom line: the idea that the LCROSS study did not detect any gold simply doesn't carry water (see attached chart).
« Last Edit: 03/20/2013 02:17 pm by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Thread 2 - Taking it to the next level
« Reply #1 on: 03/16/2013 02:57 pm »
I made a numerical simulation program that has already provided some interesting results. The simulated environment was based on Andrew Poppe's Ph.D. thesis "Modeling, Theoretical and Observational Studies of the
Lunar Photoelectron Sheath". He did a sophisticated particle in cell (PIC) simulation to estimate what the electron sheath is above the surface at about Lunar noon.

Mine takes his environmental parameters and then runs various test particles to see what happens. My results were pretty close to his test particles: e.g., he describes a 0.02 μm (radius) dust particle that levitates at about 8.5 meters with a surface voltage of about 3V and a charge of about 40 elementary charges. My particle levitated at ~9.6 meters with a charge of 50 elementary charges and an equilibrium surface potential of 3.6 volts, so we're in the same ballpark, and certainly within the natural range of variation in Lunar conditions.

The first test was to see the effect of the photoelectric efficiency η (the fraction of emitted photoelectrons per incident photon. The standard value for η in most paper is 0.1 for dielectric dust particles, and 1.0 for metals.

Initially I used those values, and sure enough, the metal particles charged to a much higher voltage and charge compared to the ordinary regolith dust particles (about twice as high), leading to higher accelerations and velocities upon launching.

However, the cutoff size for launching (above which they could not be lofted) was similar for both kinds of particles (0.09 μm). They also tended to have similar levitation heights, although the "olivine" particles tended to have slightly higher levitation heights.

(An interesting aside: theory predicts that there should be multiple heights where the lunar and electrostatic forces are in balance, but that the lower one is usually considered to be unstable. However, for certain particles (e.g., 0.7 μm "olivine" particles), I could get it to stably levitate at either 0.7 meters or 6.5 meters depending on the starting conditions.)

Since the effort was in order to see whether gold could be preferentially separated from regolith, however, the above-described results were not conclusive in that both particles exhibited rather similar behaviors, despite large differences in densities and photoelectric efficiencies.

However, it should be noted that the submicron, nanoscale particles we're looking (10's of nm) at are actually small relative to the wavelength of the UV photons energizing them (~100 nm). So according to some work by Abbas and colleagues (see attachments) the photoemission efficiency factors for such small particles in fact range from 10^-2 to 10^-5, rather than 10^-1. When an η of 0.01 was put into the simulation for the "olivine" particles, they could not get off the ground at all, and in fact tended to charge negatively. Meanwhile, gold particles could still get lofted, even at an η of 0.1, so I think that's going to be the key....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Thread 2 - Taking it to the next level
« Reply #2 on: 03/19/2013 11:44 am »
Here's a chart that compares the levitation behavior of gold particles to regolith particles. As you can see, the gold particles charge up a lot faster, but that regolith particle eventually reaches a higher average levitation height....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Robert Thompson

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Re: Gold Moon - Thread 2 - Taking it to the next level
« Reply #3 on: 03/19/2013 01:06 pm »
I've been chewing my steak (biding) on this idea since LCROSS 2009 (the day we didn't see a plume like they said we would). One quality of gold that occurs to me just now is its ductility. Can we surmise any weird factors associated with impacts of siderophile / KREEP-bearing bodies that would cause this quality to result in "more" nanometer/micron size particles than other materials. I.e., does ductility, in >addition< to electronegativity, cause any preferential feature. And here I sort of visualize 'splashing' on nanometer scales.

http://hypertextbook.com/facts/1999/JeniferVilfranc.shtml

Offline Warren Platts

Re: Gold Moon - Thread 2 - Taking it to the next level
« Reply #4 on: 03/19/2013 02:22 pm »
I've been chewing my steak (biding) on this idea since LCROSS 2009 (the day we didn't see a plume like they said we would). One quality of gold that occurs to me just now is its ductility. Can we surmise any weird factors associated with impacts of siderophile / KREEP-bearing bodies that would cause this quality to result in "more" nanometer/micron size particles than other materials. I.e., does ductility, in >addition< to electronegativity, cause any preferential feature. And here I sort of visualize 'splashing' on nanometer scales.

http://hypertextbook.com/facts/1999/JeniferVilfranc.shtml

I'm not sure how the ductility per se fits into the picture; as indicated above, I suspect that the vast majority of gold particles are going to be submicron-sized. I guessing that's because the hydrothermal processes on Earth that concentrate gold and make the big nuggets don't exist on the Moon....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Multiple Equilibrium
« Reply #5 on: 03/20/2013 02:17 pm »
This chart shows the existence of multiple equilibrium points for certain choices of parameters. All test particles were assumed to be olivine and dropped from a height of 7 meters with different charges: (1) 168 (which is the equilibrium charge for the upper level, and (2) 22, and (3)21. The middle particle that escapes the lower zone eventually reaches an equilibrium height of 6.5 meters if you let it run long enough--that is, there are not 3 different equilibrium points.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Thread 2 - Photoelectric Efficiency
« Reply #6 on: 03/20/2013 08:36 pm »
This one shows the effect of photoelectric efficiency (defined as the number of incident UV photons divided by the number of photoelectrons liberated).

As you can see, in this simulation, there is a sharp cutoff between 0.07 and 0.061; at 0.060, the "regolith" test particle can't levitate at all. Laboratory work by Abbas et al. on actual Apollo 17 regolith samples measured photoelectron efficiencies for submicron sized particles that ranged from 10-2 to 10-5; all such values are well below 0.06!

So I think here I've identified a key difference in the properties of gold  dust versus ordinary dust that proves decisive in terms of their ability to transport via electrostatic levitation....

EDIT:

I added a diagram from Abbas et al. (2007) that shows the extreme drop off in photoelectric efficiency of submicron sized lunar dust collected by Apollo 17.
« Last Edit: 03/23/2013 12:17 pm by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline alexterrell

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Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #7 on: 03/21/2013 02:34 pm »
Can you use the electrostatic properties of gold to mine an area?

Use a laser to re-charge it and then attract it towards a charged grid?

Would sure beat panning.

Offline Warren Platts

Can you use the electrostatic properties of gold to mine an area?

Use a laser to re-charge it and then attract it towards a charged grid?

Would sure beat panning.

Interesting idea! However, there are going to be a lot of volatiles as well as other native metals in the mix. We'll want the volatiles anyway to make rocket fuel to send the gold home and bring in supplies.

I was kind of envisioning excavating the frozen regolith, baking off of the volatiles in a kiln, then running the stuff through an industrial electrostatic separator, then washing in mercury (which should also be abundant in such craters), then evaporating the mercury off to leave the metallic gold. If there's too much silver mixed in, possibly electrochemical purification might be required as well.

Other options are possible: LCROSS found a lot of other chemicals in the brew, so something like cyanide leaching could also be used....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline HappyMartian

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Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #9 on: 03/23/2013 08:54 am »
Warren, are you thinking about getting your numerical simulation research published in a research journal? You should publish.

Gold and ISRU propellant in the Moon's polar regions could be a really sweet combination.

Keep on doing your very useful numerical simulation work!
"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

Offline Warren Platts

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #10 on: 03/23/2013 12:11 pm »
Warren, are you thinking about getting your numerical simulation research published in a research journal? You should publish.



Keep on doing your very useful numerical simulation work!

Actually, I'm supposed to deliver a presentation on this topic at the Planetary & Terrestrial Mining Sciences Symposium in Toronto this year...

http://www.ptmss.com/Detailed_Schedual.aspx

I'm going to try to make it. Should be good. Dallas Bienhoff is supposed to be there, as well as Jim Keravala and Bob Richards from Shackleton Energy and Moon Express respectively, as well as reps from two asteroid mining hopefuls (but no one from Planetary Resources).

Quote
Gold and ISRU propellant in the Moon's polar regions could be a really sweet combination.

If we take the LCROSS results at their face value, a mine that produced 200 mT of Au would also produce about 10,000 mT of LH2/LO2 propellant....

This represents a huge advantage pertaining to electrostatic placer deposits--if they are real. Most other proposals to get precious metals either go after metallic asteroids (which don't have volatiles) or look for metallic asteroid impact sites on the Moon (which typically won't be found within polar PSR's--although it would be neat to find a big permanently shaded crater that was formed by a metallic asteroid!)

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #11 on: 05/12/2013 01:46 pm »
Here's a pdf of my powerpoint for the PTMSS/CIM conference. Presentation apparently well received! :)
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Robert Thompson

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Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #12 on: 05/13/2013 08:31 am »
:). Great move to push the general idea. Now, your slide 24 made me go snooping around...

http://www.nature.com/nature/journal/v476/n7358/full/nature10289.html
Forming the lunar farside highlands by accretion of a companion moon
Jutzi & Asphaug, Nature 476, 69–72 (04 August 2011)
says: "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."

http://www.skyandtelescope.com/news/126785643.html
Big Splat Could Have Reshaped the Moon
Shweta Krishnan Aug 4, 2011
"In Jutzi and Asphaug’s simulations, this body was about a third the young Moon’s diameter and added 4% to its mass — enough rock to thicken the entire far-side crust by 30 miles (50 km)."

http://www.sciencemag.org/content/338/6112/1272.summary
Richard A. Kerr, Peering Inside the Moon to Read Its Earliest History
Science 7 December 2012: Vol. 338 no. 6112 p. 1272
(1 summary, 3 science papers)

http://www.planetary.org/blogs/emily-lakdawalla/2012/12110923-grail-results.html
Isostasy, gravity, and the Moon: an explainer of the first results of the GRAIL mission
Emily Lakdawalla, 2012/12/11
"A second notable feature: generally, the crust is thick (low Bouguer gravity, blue color) on the farside and thin (high Bouguer gravity, red color) on the nearside. This is a known feature of the Moon; it produces what's known as its center-of-figure/center-of-mass offset. The Moon's geometric center is offset from its rotational center by several kilometers. One hypothesis to explain this oddity is that most of the farside is covered by very thick deposits of ejecta from the giant south pole-Aitken basin."

For the support of the idea shown by GRAIL members early on, neither Jutzi, Asphaug or 'big splat' are even glancingly inferred in the GRAIL results papers or by Lakdawalla. I could find no credible reference to them after 2011. From the articles themselves, I gather that a second moon at L4/L5 would not be large enough to differentiate, and would only have the same elemental composition as the first moon. Therefore when it impacted and smeared on what has become the far side of the moon at present, there would be no particularly profound difference in elements, even if there might be in chemical compositions due to differing thermal and pressure environments, and there would be no particularly rich deposits of differentiated precious elements (i.e., no core, no differentiation). I am all ears to any other news of the 'big splat' but I'm not seeing it on the radar presently.

Offline Warren Platts

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #13 on: 05/13/2013 05:15 pm »
I agree the Big Splat Hypothesis is very speculative. However, I don't see how GRAIL contradicts it. E.g., see attached map: the crustal thickness on the Far Side is about 30 km thicker than the Near Side--exactly what Asphaug & Jutzi predicted.

I agree that if the moonlet formed in the EML4/5 point(s), then it would be similar to the Moon's composition. At least it wouldn't have gone through a double depletion of siderophiles as has the Moon: 1st siderophiles were depleted from Earth's mantle by dropping to Earth core; 2nd, after Moon formed another depletion occurred when siderophiles deposited in Moon core.

On the other hand, it's perhaps barely conceivable that the moonlet happened to form at a Sun-Earth libration point, in which case there would have been no depletion of siderophiles, and it could be expected to have the Earth's bulk concentration of gold. This would be huge, and would radically increase the amount of gold on the Moon.

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Robert Thompson

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Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #14 on: 05/25/2013 04:11 pm »
http://www.space-travel.com/reports/New_method_for_producing_clean_hydrogen_999.html
"The Duke engineers, using a new catalytic approach, have shown in the laboratory that they can reduce carbon monoxide levels to nearly zero in the presence of hydrogen and the harmless byproducts of carbon dioxide and water. They also demonstrated that they could produce hydrogen by reforming fuel at much lower temperatures than conventional methods, which makes it a more practical option."

Offline Warren Platts

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #15 on: 05/25/2013 05:54 pm »
This is interesting:

Quote
In this case, the catalysts were nanoparticle combinations of gold and iron oxide (rust), but not in the traditional sense. Current methods depend on gold nanoparticles' ability to drive the process as the sole catalyst, while the Duke researchers made both the iron oxide and the gold the focus of the catalytic process.

This is interesting. There is something strange going on in the anomalous craters. I believe there might be some sort of synergistic effect between gold, other native metals, the H2O, and H and OH that causes them to somehow ground out the electrical forces, causing the craters to be "sticky" allowing cool stuff to accumulate...
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #16 on: 02/14/2014 09:49 am »
Warren, are you thinking about getting your numerical simulation research published in a research journal? You should publish.

Gold and ISRU propellant in the Moon's polar regions could be a really sweet combination.

Here's a copy of the paper we presented at the AIAA SciTech conference last month.
« Last Edit: 02/16/2014 11:54 am by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline TrevorMonty

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #17 on: 02/16/2014 07:34 am »
Warren, are you thinking about getting your numerical simulation research published in a research journal? You should publish.

Gold and ISRU propellant in the Moon's polar regions could be a really sweet combination.

Here's a copy of the paper I presented at the AIAA SciTech conference last month.
Great article Warren, the movement of gold by static electricity was very insightful.
If your estimates of gold reserves in craters proves correct, gold may yet again be driving force to opening up another frontier.

Offline TrevorMonty

Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #18 on: 02/16/2014 07:59 am »
Just did some research on current gold prices. A dragon capsule can return $140M of gold based on today's prices.

Offline HappyMartian

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Re: Gold Moon - Thread 2 - Numerical Simulation Results
« Reply #19 on: 02/20/2014 11:03 pm »
Just did some research on current gold prices. A dragon capsule can return $140M of gold based on today's prices.

The Moon is a transportation hub. Eventually, build electromagnetic catapults and throw capsules at Antarctica and Mars.
"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

 

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