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Thread: Gold Mining on The Moon

  1. #541
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    Quote Originally Posted by kamaz View Post
    Quote Originally Posted by Jon Clarke
    This process just moves particles, it does not concentrate gold.
    Of course. However, the idea is that if a particle can move randomly on lunar surface, it will sooner or later encounter a trap which it can't escape. Over time, all the movable gold will end up in traps. So the traps (either polar traps, or the Sinus Iridum trap I have postulated above) will contain concentrated gold.
    Jon's point was that even if gold was movable via the electrostatic transport mechanism, there's no reason to think that it would preferentially transport gold, and therefore, no reason to think that gold would get concentrated with respect to ordinary dirt.

    What you're both missing is that in the aftermath of an asteroid collision, the gold particles should be smaller than than silicate particles because of the relatively low boiling temperature of gold compared to silicate rocks. This will allow gold to travel further from the impact site than silicates before condensation, and since the particles will be moving apart from each other on average, the chance for collisions, and hence growing clumps diminishes the further from the impact site that a given particle travels. Moreover, according to your own chart, the smaller particles will tend to get accelerated more than larger particles, and will thus preferentially travel more than large particles. Thus you have a mechanism for transporting gold preferentially compared to ordinary silicate rocks.

    It also might be the case that gold is more likely to get charged by the solar wind than ordinary dust particles. Given that gold is an excellent conductor, I suspect this might be the case, but don't quote me on that....

    I actually agree with that: no in situ measurements = no gold.
    Absence of evidence is not evidence of absence, and in any case, there is some evidence:

    • the LAMP results are consistent with gold concentrations up to 1.6%;
    • there are unmistakable signs of silver and mercury--of this there can be no doubt;
    • silver, mercury, and gold have roughly the same cosmic abundance;
    • the presence of the silver in the LAMP results is difficult to explain as a result of contamination--there isn't enough solder in the Centaur 3rd stage;
    • the argument that Jon raised that mercury is concentrated because it is a "volatile", and since gold isn't as volatile as mercury, then gold cannot get concentrated like mercury--this does not explain the silver results, and therefore probably does not apply to gold either;
    • electrostatic transport favoring of smaller grains will preferentially concentrate gold particles.


    Does this add up to proof beyond a reasonable doubt? No, but IMHO, the preponderance of the evidence that we now have in hand actually favors the presence of heretofore surprisingly high concentrations of gold in these polar cold traps.

    The LCROSS results with respect to gold are very intriguing and should be followed up with all possible vigor, just because if they pan out, it could very well close the case for the first business opportunity on the Moon capable of generating a dollar proft. This is important not just for the investors who will get rich; it would also represent an important milestone in global human history.

    To dismiss the gold results out of hand like Jon Clarke does I chalk up more to the fact that the more interesting the Moon looks, the more likely it is that the Moon will suck limited resources that could be spent on a Mars effort instead than to any solid evidential basis.

  2. #542
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    Quote Originally Posted by RGClark View Post
    M3 - Moon Mineralogy Mapper.
    Excellent! So our theory is easier to verify then I expected. Now, if only there was some publicly available tool for extracting spectra from raw M3 data...

    Another problem is that energy resolution is quoted as between 10-40nm, so it will not show finely defined peaks. On the other hand, spatial resolution is about 70-140m per pixel, so it can at least produce pretty pictures

  3. #543
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    Quote Originally Posted by kamaz View Post
    Of course. However, the idea is that if a particle can move randomly on lunar surface, it will sooner or later encounter a trap which it can't escape. Over time, all the movable gold will end up in traps. So the traps (either polar traps, or the Sinus Iridum trap I have postulated above) will contain concentrated gold.
    No so fast! We have a transport mechanism for dust. That dust we know has very little gold in it. Any dust transported will have similar gold content to the source areas and therefore any dust accumulating in the cold traps will have very low concentrations of gold. We have no evidence what so ever for preferential gold transport, and quite a bit of evidence against it.

    How much gold is in the traps we don't know, as we don't know how much movable gold was deposited on the Moon in the first place. (In this model, movable gold is gold sitting on the surface, in grains small enough to be moved around by the electrostatic transport).
    We do know how much gold is in the source areas because we have samples of lunar rocks and regolith. Less than 1 ppb.

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    Alright. While we are at it, there is another problem which bugs me with all this, so I will just post it here:

    LCROSS has found a water/rock brew at the South Pole coldtraps. Chandrayaan has found solid ice in the North Pole coldtraps. Why? If transport was by random walk, then composition of stuff at both poles should be exactly the same.

    If we assume that water moves by volatilizing and dust (i.e. metals) moves by electrostatic transport, then it implies existence of a magnetic field which diverts the dust. Since the charged dust moves West, then in order to be diverted South, it would have to move in a magnetic field which is directed down (normal to the surface). This, however is completely insane. First, the Moon does not have a magnetic field. Second, a field of such shape would mean that the Moon is (was) a magnetic monopole, which, according to the current understanding of electromagnetism cannot exist, yet alone on planetary scale!

    I'd say that we're missing some critical pieces of this puzzle.

  5. #545
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    Quote Originally Posted by Hernalt View Post
    Truth is the first casualty. So are honest questions. Where's a cold war when you need one? Anyway!
    I agree that the high vaporization energy of gold is not the first thing to suggest a mechanism for gold in a cold trap. A different and more constant mechanism is electrostatic dust transport. Solar wind UV photons knock out electrons from surface particles, positively ionizing them and making them prone to levitation and movement.
    "Impact of Dust on Lunar Exploration" (2006)
    http://hefd.jsc.nasa.gov/files/stubb...ation.4075.pdf
    "The Lunar Ejecta and Meteorites (LEAM) experiment was placed on the lunar surface by Apollo 17 to detect hypervelocity impacts from meteoroids. Surprisingly, the measurements were dominated by high velocity impacts (up to 1 km s−1) from electrostatically charged dust [11]. Interestingly, the counts registered by LEAM peaked around the terminator, especially at sunrise..."
    "Electrostatic and Gravitational Transport of Lunar Dust in the Airless Atmosphere of the Moon" (2008)
    http://ieeexplore.ieee.org/xpls/abs_...=4658912&tag=1
    "At the terminator, the two electric fields interact with each other. The electrostatic field lines form the positive side can terminate at the negative side, thus intensifying the field strength. Any minute disturbance on the surface may cause a stream of particles moving as fountains of dust from one side to the other [4, 7, 9]."
    "The Lunar Dusty Exosphere: The Extreme Case of an Inner Planetary Atmosphere" (2008)
    http://lunarscience.arc.nasa.gov/pdf...per_091409.pdf
    (See diagram.)
    Seminars (for Scientists) Spring 2010
    http://lasp.colorado.edu/home/about/...r-spring-2010/
    "Laboratory Studies of Lunar Dust Transport" (By undergrads, it appears.)
    http://lasp.colorado.edu/seminars/fi...15_Xu_Wang.pdf
    See "Dust Transport in Craters" slide 33/40, showing picture of Eros crater.
    "Electrostatic dust transport on Eros: 3-D simulations of pond formation" (2008)
    http://www.sciencedirect.com/science...2&searchtype=a
    "NEAR–Shoemaker spacecraft images of the surface of the near-Earth Asteroid 433 Eros reveal that more than 200 craters on Eros are partially filled with smooth deposits, termed ponds [Veverka, J., and 32 colleagues, 2001a. Science 292, 484–488]. These ponds appear smooth even at a high resolution of 1.2 cm/pixel and spectral analysis suggests that they may be made up of particles much less-than50 μm in size [Robinson, M.S., Thomas, P.C., Veverka, J., Murchie, S., Carcish, B., 2001. Nature 413, 396–400; Riner, M.A., Eckart, J.M., Gigilio, J.G., Robinson, M.S., 2006. Lunar Planet. Sci. XXXVII. Abstract 2291]. Coupled with the concentration of ponds at low latitudes, the possible small particle size suggests that these deposits might be related to electrostatic transport of dust near the local terminator" (Note that Eros orbits at 1.change AU, ergo less solar incidence.)
    I cannot get access to this:
    Interplanetary Dust and Zodiacal Light, Lecture Notes in Physics, 1976, Volume 48/1976, 238-240, DOI: 10.1007/3-540-07615-8_487
    "Electrostatic disruption of lunar dust particles" John W. Rhee
    Thoughts before Apollo:
    "Electrostatic Dust Transport on the Lunar Surface" (1962)
    http://www.sciencedirect.com/science...3&searchtype=a
    The question I would pose to Bobunf, or anyone else impartial, is whether or not the electrical and chemical properties of gold lend any particular conclusions in light of this well-documented phenomena. I can surmise that the lunar surface gets the full solar incidence, UV and Xray spectra of 1 AU, has 1/6 gravity, and has enough electrical field at the surface to loft Ca particles, atomic weight 40, whereas the weights of elements discussed are: Ag ~107, Au ~198, Hg ~200. Is there an excellent impartial silver bullet argument to be made against the idea that gold particles can be positively charged and make small jumps across the day/night terminus, and in so doing some of them might march across a day/crater interior terminus?...
    Thanks for those references. That seminar presentation at the LASP laboratory at the University of Colorado might be especially useful:

    Laboratory studies of lunar dust transport.
    There has been much evidence indicating dust levitation and transport on or near the lunar surface. Dust mobilization is likely to be caused by electrostatic forces acting on small lunar dust particles that are charged by UV radiation and solar wind plasma. Laboratory studies are needed for understanding physics of dust charging and dynamics on the lunar surface. Differential photoelectric charging and so-called “supercharging” on the surface near the lunar terminator region were created and studied in laboratory. Dust transport on surface in plasmas was investigated. A dust pile was observed to spread and form a diffusing dust ring on a negatively biased conducting surface in plasma. A dust patch was also found to spread on an electrically floating surface in plasma with an electron beam. Dust hopping was confirmed by noticing grains on protruding surfaces in both experiments. The 2-D electrostatic potential distributions were measured above the dusty surfaces and show electrostatic forces required for transport of the dust particles.
    http://lasp.colorado.edu/seminars/fi...15_Xu_Wang.pdf

    The researchers were able to recreate electrostatic dust levitation in the lab. An interesting follow up experiment to do would be to see if concentration of elemental metals increases the height or the speed at which the particles can be elevated, and if so, which metals have the most effect.

    Also, found these news articles when looking up references to the LADEE lunar mission scheduled to launch May 2012:

    Lunar Dust Transport Still a Mystery.
    by NANCY ATKINSON on DECEMBER 15, 2010
    http://www.universetoday.com/81727/l...ill-a-mystery/

    LADEE Mission to Study the Moon's Fragile Atmosphere.
    October 26, 2009 by Patrick Barry
    Right about now, you might be thinking to yourself: "Hold on a second. I thought the Moon doesn't have an atmosphere!" And you would be almost correct. The Moon's "atmosphere" is so tenuous that it's technically considered an exosphere, not an atmosphere.
    "It's not anything like an atmosphere we would think of," Colaprete says. For example, a cubic centimeter of Earth's atmosphere at sea level contains about 100 billion billion molecules. That same volume of the Moon's exosphere contains only about 100 molecules.
    In fact, that's so thin that molecules in the lunar exosphere almost never collide with each other. Rather than constantly ricocheting off each other to create a cohesive, swarming mass of molecules as happens in Earth's atmosphere, molecules in the lunar exosphere fly unimpeded, like microscopic cannon balls following curved, ballistic trajectories.
    And the weirdness of the exosphere doesn't stop there. During the lunar night, the Moon's exosphere mostly falls to the ground. (Just imagine if our atmosphere fell to the ground at night!) When sunlight returns, the solar wind kicks up new particles to replenish the exosphere.

    http://www.physorg.com/news175800054.html

    Part of the Ladee mission is to study this electrostatic dust transport so we might have a much clearer understanding of how this works next year.


    Bob Clark
    Last edited by RGClark; 2011-Jan-23 at 02:55 PM.

  6. #546
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    Quote Originally Posted by kamaz View Post
    Excellent! So our theory is easier to verify then I expected. Now, if only there was some publicly available tool for extracting spectra from raw M3 data...
    Another problem is that energy resolution is quoted as between 10-40nm, so it will not show finely defined peaks. On the other hand, spatial resolution is about 70-140m per pixel, so it can at least produce pretty pictures
    Funny, I was looking up references to the spectral resolution of the LAMP and VSP instuments on LCROSS when I found this site that has links to the full text papers in Science on the LAMP observations, "LRO-LAMP Observations of the LCROSS Impact Plume" and on the VSP observations, "The LCROSS Cratering Experiment":

    http://www.geo.utep.edu/pub/hurtado/..._water_102110/

    The LAMP paper on that page is the file: "gladstone_etal_2010_science_lro-lamp_lcross.pdf".
    And the VSP paper on that page is the file: "schultz_etal_2010_science_lcross.pdf".

    This is from the web page for a class in planetary geology at the University of Texas at El Paso in Fall, 2010:

    Planetary Geology
    Lectures and Labs
    http://www.geo.utep.edu/pub/hurtado/...ures_index.htm

    On this page also are links to other full text papers on Mars and lunar science.

    Bob Clark

  7. #547
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    Quote Originally Posted by kamaz View Post
    Alright. While we are at it, there is another problem which bugs me with all this, so I will just post it here:

    LCROSS has found a water/rock brew at the South Pole coldtraps. Chandrayaan has found solid ice in the North Pole coldtraps. Why? If transport was by random walk, then composition of stuff at both poles should be exactly the same.

    If we assume that water moves by volatilizing and dust (i.e. metals) moves by electrostatic transport, then it implies existence of a magnetic field which diverts the dust. Since the charged dust moves West, then in order to be diverted South, it would have to move in a magnetic field which is directed down (normal to the surface). This, however is completely insane. First, the Moon does not have a magnetic field. Second, a field of such shape would mean that the Moon is (was) a magnetic monopole, which, according to the current understanding of electromagnetism cannot exist, yet alone on planetary scale!

    I'd say that we're missing some critical pieces of this puzzle.
    I would not read too much into this. The results are from different instruments obtaining data by different means, on different spacecraft, looking at different localities and interpreted by different teams. It is not suprising that these very preliminary results appear different. It does not mean there is no solid ice at the South Pole and no water-rock mixtures at the North.

  8. #548
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    Why would you assume that both poles would be the same? The cratering is much different, for a start, as is insolation and albedo. I'd expect things to be different, outside of what JonClarke is saying (which also makes sense).

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  9. #549
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    Quote Originally Posted by RGClark View Post
    ...
    Also, found these news articles when looking up references to the LADEE lunar mission scheduled to launch May 2012:

    Lunar Dust Transport Still a Mystery.
    by NANCY ATKINSON on DECEMBER 15, 2010
    http://www.universetoday.com/81727/l...ill-a-mystery/

    LADEE Mission to Study the Moon's Fragile Atmosphere.
    October 26, 2009 by Patrick Barry
    Right about now, you might be thinking to yourself: "Hold on a second. I thought the Moon doesn't have an atmosphere!" And you would be almost correct. The Moon's "atmosphere" is so tenuous that it's technically considered an exosphere, not an atmosphere.
    "It's not anything like an atmosphere we would think of," Colaprete says. For example, a cubic centimeter of Earth's atmosphere at sea level contains about 100 billion billion molecules. That same volume of the Moon's exosphere contains only about 100 molecules.
    In fact, that's so thin that molecules in the lunar exosphere almost never collide with each other. Rather than constantly ricocheting off each other to create a cohesive, swarming mass of molecules as happens in Earth's atmosphere, molecules in the lunar exosphere fly unimpeded, like microscopic cannon balls following curved, ballistic trajectories.
    And the weirdness of the exosphere doesn't stop there. During the lunar night, the Moon's exosphere mostly falls to the ground. (Just imagine if our atmosphere fell to the ground at night!) When sunlight returns, the solar wind kicks up new particles to replenish the exosphere.

    http://www.physorg.com/news175800054.html

    Part of the Ladee mission is to study this electrostatic dust transport so we might have a much clearer understanding of how this works next year.
    The LADEE lunar orbiter is supposed to have a spectral resolution of only 0.7 nm over the spectral range of 230 - 830 nm so might be able to make these gold or silver detections:

    2009 NLSI Forum, NASA Ames Research Center
    Optical Scattering at the Moon: Predictions for the LADEE UV-VIS Spectrometer
    http://lunarscience2009.arc.nasa.gov...Compatible.pdf


    Bob Clark

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    Quote Originally Posted by kamaz
    I'd say that we're missing some critical pieces of this puzzle.
    Then how do you explain the silver results?

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    Quote Originally Posted by Ara Pacis View Post
    Can spectroscopy be used without a plume, using sunlight? Might a laser be used to induce a plume for spectroscopy? (A laser on a lunar-orbiting spacecraft, I'm not proposing one emitted from Earth. Or would solar focusing optics be lighter?)
    Both of these might be doable. Laser lunar ranging experiments are able to get detectable returned photons using only a 2.3 watt laser:

    The Basics of Lunar Ranging.
    http://www.physics.ucsd.edu/~tmurphy/apollo/basics.html

    Clearly this returned signal is greatly attenuated. However, we now have megawatt class lasers available that can put out light for 5 second long bursts:

    Boeing YAL-1.
    http://en.wikipedia.org/wiki/Boeing_YAL-1

    This is an airborne system intended for missile defense. The laser undergoes attenuation and spreading in passing through the atmosphere at more or less constant density. However, pointing upward through air of ever decreasing density should result in reduced attenuating of the beam intensity. Moreover, it might be possible to have a hovering lens or mirror at higher altitude that would focus the beam even further before heading toward the Moon. A ca. million times more intense beam than the lunar ranging beams with additional focusing at high stratospheric altitude should result in detectable spectra using our largest ground based scopes.
    Also, I did a calculation that suggests with even a modest sized reflecting surface in orbit about the Moon oriented to illuminate the lunar surface, we should be able to get detectable spectra with our largest ground based telescopes.
    This calculation would probably take us too far afield from this thread so I posted it to a separate thread in the "Space/Astronomy Questions and Answers" forum:

    Space mirrors orbiting the Moon to improve observations?
    http://www.bautforum.com/showthread....e-observations


    Bob Clark

  12. #552
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    BUMP

    Quote Originally Posted by JonClarke View Post
    Quote Originally Posted by kamaz
    However, the idea is that if a particle can move randomly on lunar surface, it will sooner or later encounter a trap which it can't escape. Over time, all the movable gold will end up in traps. So the traps (either polar traps, or the Sinus Iridum trap I have postulated above) will contain concentrated gold.
    No so fast! We have a transport mechanism for dust. That dust we know has very little gold in it. Any dust transported will have similar gold content to the source areas and therefore any dust accumulating in the cold traps will have very low concentrations of gold. We have no evidence what so ever for preferential gold transport, and quite a bit of evidence against it.
    I believe this is wrong. It is a general principle of geology that any transport process is going to preferentially separate and concentrate the various constituents. Clearly, since electrostatic dust transport is being invoked here as the theory, it would not at all be surprising that gold and other native metals might be preferentially transported, given their radically different electrostatic properties, relative to the dielectric regolith, which has a conductivity on the order of candle wax.

    Indeed, electrostatic separation is a major industrial process used all the time right here on Planet Earth. It's used for everything from separating out pebbles from dried beans, separating out metals from plastics in recycling streams--and separating out gold particles. In fact, Thomas Edison himself patented the world's first electrostatic separator, and it was for getting gold: they found an old placer deposit of gold out in the Arizona desert where there was no water for conventional dredging, so Edison invented a waterless process: electrostatic separation.

    To test the hypothesis, I programmed a numerical simulation. First test particle runs using initial conditions virtually the same as Andrew Poppe's PhD thesis (basically Lunar noontime conditions):

    radius = 0.02 micrometers
    total simulation run time = 25 hours
    time step = 0.1 seconds
    initial height = 0
    initial charge = 0

    Olivine particle
    input:
    photoelectric efficiency = 0.1
    density = 3250 kg/m^3

    output:
    max velocity = 0.334 m/s
    max acceleration = 0.315 m/s^2
    max charge = 50 elementary charges
    equilibrium surface potential = 3.609 Volts
    levitation height = ~9.3 m

    Au particle
    input:
    photoelectric efficiency = 1.0
    density = 19320 kg/m^3

    output:
    max velocity = 0.809 m/s
    max acceleration = 0.690 m/s^2
    max charge = 103 elementary charges
    equilibrium surface potential = 7.397 Volts
    levitation height = ~9.0 m

    So there you have it. Due to the higher photoelectric efficiency alone, gold particles will charge to twice the surface potential of same-sized ordinary dust grains, thus gaining twice the charge, and hence higher accelerations and velocities than same-sized particles....


    Quote Originally Posted by Jon Clarke
    Quote Originally Posted by kamaz
    How much gold is in the traps we don't know, as we don't know how much movable gold was deposited on the Moon in the first place. (In this model, movable gold is gold sitting on the surface, in grains small enough to be moved around by the electrostatic transport).
    We do know how much gold is in the source areas because we have samples of lunar rocks and regolith. Less than 1 ppb.
    And this is not true either. There was a fairly recent article that looked at a variety of "pristine" rock samples from the Apollo 12 mission. I'm too lazy to look it up right this second, but IIRC, they averaged roughly 5 ppb. Meanwhile, there was a core sample taken by the Apollo 12 crew from the regolith at the site. It averaged only 2 ppb, leaving 3 ppb unaccounted for. If the 3 ppb found it's way to the PSR's, that would be a concentration factor of about 50,000, yielding an expected 150 ppm in the polar cold traps. Note that 150 ppm is considered an extremely rich ore on Planet Earth.

    But wait. There's more. Recent research suggests that solar wind electron clouds will collect in the wake of shaded craters, causing a strong ambipolar electric field and that particles in the shadow will get charged by collecting electrons, and then launched into space once again, even with no sunlight. This would cause more erosion of volatiles and native metals, concentrating them within crevices and craters within craters that are protected enough from such solar wind wake effects. This could easily result in an another order of magnitude concentration. Thus 10 * 150 ppm = 1.5 ppt.

    Note that the LCROSS results reported by Gladstone et al. originally reported a 2σ upper limit concentration of 1.6%. However, an erratum was later published whereby they lowered their estimates by a factor of 5.47: 1.6% / 5.47 = 3 ppt. Now of course that's only an upper limit, but it's easy to calculate the most likely expected value. That turns out to be 1 ppt: erf(1 ppt/(1.5 ppt * sqrt(2)) = 0.50;

    I call that a bullseye....
    Attached Images Attached Images
    Last edited by Warren Platts; 2013-Mar-16 at 12:53 PM.

  13. #553
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    Here's the reference to the Apollo 12 rocks:

    Snyder et al. 1997. PLATINUM-GROUP ELEMENTS (PGEs) AND GOLD (Au) IN THE LUNAR REGOLITH: ROUTINE
    ANALYSIS BY ULTRASONIC NEBULIZATION-INDUCTIVELY COUPLED PLASMA-MASS
    SPECTROMETRY (USN-ICP-MS).

    Not counting the outlier impact melt that had 22 ppb Au, they analyzed 7 rock samples that had an average concentration of ~5.6 ppb, so I just round that down to 5 ppb.

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    Here's a chart I made from data from the simulation that compares same-sized particles of gold versus regolith.

    Attached Images Attached Images
    Last edited by Warren Platts; 2013-Mar-19 at 03:15 PM.

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    And here is a chart showing the effect of photoelectric efficiency on the ability of a particle to levitate. In the chart in the previous post, I assumed that the photoelectric efficiency (PE--defined as number of incident uv photons over number of ejected photoelectrons) of regolith dust particles was ~0.1; however, at the length scale we're talking about, the PE is going to be << 0.1; (see attached charts from Abbas et al. 2007. "LUNAR DUST CHARGING BY PHOTOELECTRIC EMISSIONS"). Indeed, using their "length scale", the length scale for a 0.02 micrometer radius particle, the length scale is ~1, which places it at the very extreme left of the graph.

    At these PE's they simply will not levitate under the conditions of the simulation (noontime). Meanwhile, gold will retain a high PE (in my simulation the 0.02 micrometer "gold" particles can still levitate at a PE of 0.1). So I think I've clearly found at least one mechanism that will favor native metal dust transport over ordinary regolith dust.

    Attached Images Attached Images
    Last edited by Warren Platts; 2013-Mar-21 at 12:05 PM.

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    The magnetic field of the Sun and the magnetic field of the Earth should both be present on the surface of the Moon added vectorally, and modified by nearby magnetic materials. I don't think the ionized dust cares that the moon did not produce the magnetic field. Neil

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