Using Solar Power on 100 Meter Towers for 100X Lunar Polar Mining

The Lunar Polar Gas-Dynamic Mining Outpost (LGMO) is a breakthrough mission architecture that promises to greatly reduce the cost of human exploration and industrialization of the Moon. LGMO is based on two new innovations that together solve the problem of affordable lunar polar ice mining for propellant production.

The first innovation is based on a new insight into lunar topography:

Analysis suggests that there are large (hundreds of meters) landing areas in small (0.5-1.5 km) nearpolar craters on which the surface is permafrost in perpetual darkness but with perpetual sunlight available at altitudes of only 10s to 100s of meters. In these prospective landing sites, deployable solar arrays held vertically on masts 100 m or so in length (lightweight and feasible in lunar gravity) can provide nearly continuous power. This means that a large lander, such as the Blue Moon vehicle proposed by Blue Origin, a BFR (SpaceX SHS); or a modestly sized lunar ice mining outpost could sit on mineable permafrost with solar arrays in perpetual sunlight on masts providing affordable electric power without the need to separate power supply from the load.

The second enabling innovation for LGMO is Radiant Gas Dynamic (RGD) mining. RGD mining is a new Patent Pending technology invented by TransAstra to solve the problem of economically and reliably prospecting and extracting large quantities (1,000s of tons per year) of volatile materials from lunar regolith using landed packages of just a few tons each. To obviate the problems of mechanical digging and excavation, RGD mining uses a combination of radio frequency, microwave, and infrared radiation to heat permafrost and other types of ice deposits with a depth-controlled heating profile. This sublimates the ice and encourages a significant fraction of the volatiles to migrate upward out of the regolith into cryotraps where it can be stored in liquid form.

RGD mining technology is integrated into long duration electric powered rovers. In use, the vehicles stop at mining locations and lower their collection domes to gather available water from an area before moving on. When on-board storage tanks are full, the vehicles return to base to empty tanks before moving back out into the field to continue harvesting. The rover can be battery operated and recharge at base or carry a laser receiver powered by a remote laser. Based on these innovations, LGMO promises to vastly reduce the cost of establishing and maintaining a sizable lunar polar outpost that can serve first as a field station for NASA astronauts exploring the Moon, and then as the beachhead for American lunar industrialization, starting with fulfilling commercial plans for a lunar hotel for tourists.

RGD mining will allow the development of a practical system that can be constructed on a mobile platform to enable the use of a mixture of different types of radiant energy with different penetration depths to control the release of water vapor from hard lunar permafrost in such a way that it can be trapped and captured by a water collection system. Although microwave extraction methods have been proposed in the past they have typically required prior excavation of substrate material or did not include methods to prevent re-trapping of water by cold regolith. By using a multi-frequency radiant system, RGD provides a variable heating profile that sublimates water vapor in layers from the top down and encourages evolved water to migrate into cryotraps in the vehicle while minimizing refreezing of the water vapor in the surrounding substrate.

This design combines subsurface ice prospecting via low voltage DC subsurface sensing integrated with TRL-6 drills for detection and volatile gas collection in a single vehicle. We estimate that rovers sized for a New Glenn or SLS payload faring would mass between 2 and 5 tons and would each be capable of harvesting between 20 and 100 times its mass per year in water.

21 thoughts on “Using Solar Power on 100 Meter Towers for 100X Lunar Polar Mining”

  1. You’re assuming that modern spacecraft parts actually conduct significant amounts of heat. A lot of the stuff you’d need to keep warm to make them mechanically useful are well away from anything that would generate heat.

    In addition, you’re giving short shrift to radiative cooling. You’d have to do a lot of work to figure out the equilibrium between conductive warming and radiative cooling, but my money would be on the radiative side of the equation.

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  2. I proposed the idea of a verticle solar power tower before. My idea was to have the tower grasping and or anchored to the top rim of the crater. Then winch down a cable on a spool to the middle or edge of the centre of the crater. That way you get rid of most of the tower part as seen in the picture above. Way less material, less cost, less to maintain, easier to move if have to and could have several if needed. At the top could also put mirrors and convex or concave parascope devise with filters and louvers to allow extra dim to bright worklight for bots and or people if needed. My design was called the (giraffe module). Because of how it looked like a robotic giraffe. Thought of that one last year.

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  3. You’re kinda making my point for me. You’re adding complexity to account for the cold. Complexity is heavy and, well, complex.

    That said, even designing for the regular 2-week night is no picnic. I don’t know whether the extra time to radiate changes things very much. Suffice it to say that this is a major design challenge for anything that’s supposed to last more than two daylight weeks on the Moon.

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  4. Ah! That is the point. Whether building a solar sat v using the existing lunar *surface* as the sat, or this question as to towers v more cells static on the rims (in a circle, on steep slopes inside and outside the rim top), the existing surface of the Moon is a very cheap starting point.
    Another way to see this is to break O’Neill’s question into three topics: mass, volume and surface area. He is clearly right for mass and volume operations, Space is the Place! But surface area needs MAY be filled by the surface of a planet(especially an airless one). It needs more thought.
    What could be more important, or less *publicly* understood, than Space Solar?

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  5. You have lots of equipment that isn’t in contact with a heat source. It’ll get mechanically brittle.

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  6. Another problem is that since this is near one of the poles sunlight is coming in almost parallel to the ground, so you want your solar panels vertical & turning to face the sun, whether they are on the crater rim or down in the crater on top of the ice resource.
    Whether a tower to get the panels above the shadow of the crater rim, or whatever method you use to get power from the crater rim to the ice mines would be the greater expense, is unclear to me.

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  7. There is light all around on both sides of the upper parts of the crater rim. But only part of the time for any one spot. Even if it takes 5X the area of cell material to cover “the” power, the cells themselves are cheap. The structures to try to get 100% full direct sun may be more expensive overall. The beamers could be on the rim, near the cells. Huge surface areas needed.
    Reminds me of the Shimizu Moon Power idea of ring clear around lunar equator.
    Big news is the extraction method. Time to do it!

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  8. I would think that some craters had a combination of permanently and partially shadowed areas. That might be useful for a base, in that it would at least get some sun. But I’m pretty sure that any crater with permanently shadowed will have areas that are at best in the sun half the time.

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  9. What I was wondering was how much of the ice would sublimate from the advent of the thermal output of industrial mining bases and their operations.

    Of course it might be a near-infinite resourc for all practical purposes but then again the moon could be a harsh mistress 🙂

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  10. The idea is that the raised walls of craters at either pole create a “perpetually shadowed” crater floor; the heat-conductivity of regolith is so low that even if the walls heat up, they cannot transmit substantial heat to the floor. Moreover, the reflectivity of those same walls is low enough (regolith is about as dark as well-worn asphalt tarmac) that the secondary solar radiation is in some spots less than 10 W/m² (compared to nominal 1363 W/m²).  

    For instance, there is an equation in physics called the Stefan-Boltzman equation:

    W = σT⁴ which rearranges to 
    T = (W/σ) … to the 0.25 power

    If W is watts (power absorbed), and α is albedo (reflectance), then

    T = ((1 – α) W/σ) to the 0.25 power. 

    In Luna’s SUNLIT case:

    σ = 5.67×10⁻⁸ (Stefan-Boltzman constant)
    α = 0.27 (albedo, reflectivity)
    (1-α) = 0.73 (absorption, also emissivity)
    W = 1363 W (nominal solar power, averaged, year)

    T = 365° K (–273° K to C) = (92° C) → (200°F)

    However, when ambient reflected wall-light is only 10 W/m², then

    T = 106° K → (–167° C) → (–270° F)

    THAT, is cold. Cold enough to solidify nitrogen, oxygen, argon and H₂O water.

    Just saying,
    GoatGuy ✓

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  11. Big difference between sending a robot into a cold trap and performing human operations there. Nobody dies if the cold breaks something on the robot.

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  12. Surely you could make stirling “terminator” trains, circling the Moon in
    28 days (slightly slower than Phileas Fogg).

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  13. Though the illustration is thought-provoking (and representative of some modern concepts such as Bigelow Blow-up Bungalows, under the solar towers), and sitting back and considering the ⅙ nominal surface gravity of Luna, along with a complete lack of atmosphere (thus “wind”), I would think 100 meters is rather puny, all in all. Also, that the projected cylindrical PV caps are inappropriate, mass-to-power wise.  

    Since there is no possibility of wind, there is no penalty for “hanging” a great big “sail” type PV array on top, with tiny but durable motors-and-gear-trains to continually rotate the front face of the sail to face Sol. After all, the rotation takes what, about a month? 2.6 microradians per second; If the sail is 50 m wide, 50 m tall, the tip velocity is 0.065 mm/s. THat’s 240 millimeters per hour, or just under a foot per hour.  

    Since we wouldn’t want any kind of sliding power contact (right?) for durability, a longish highly braided aluminum power line could deal with the accumulated torsion, and every dozen rotations, the whole thing could un-spin at higher rotational rate (10000× is still only 650 millimeters a second, about 2 feet per second), and an accumulated 12 rotations would take what, 12 × 2 × π / ( 2.6×10⁻⁶ × 10,000× ) = 2,900 sec → 0.8 hours.  Not very long at all. Heck, maybe just do it once per revolution at ‘only’ 1000× rate. 2.5 in/s… 0.6 hr per 670 ‘solar day’ hours. Cheap.

    Just saying,
    GoatGuy ✓

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  14. I’m not sure that a sterling engine is

    • Cheaper per watt output, especially per watt of electricity, than PV panels
    • Lighter per watt of electricity output
    • More reliable than PV panels, especially when operating in lunar temperatures and lunar dust, both of which are hell on mechanical systems.
    • Easier to set up. We have decades of experience in getting nicely folded solar panels to deploy in space automatically.
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  15. This has the nice property that the landing site can be relatively flat. Landing on a crater rim is problematic from a tilt-angle standpoint. It’s also likely to be pretty difficult to get rovers into and out of craters if the base and processing equipment are on the rim. Landing on the crater floor solves both problems.

    A big down side, though: Your base is gonna be cold. We have enough trouble engineering stuff for a lunar night that lasts two weeks. Even if you can find a cold trap with a crater floor in partial sun, it seems like there’s a pretty good chance of being in the dark for up to six months. So, even if you have 100-meter towers with your solar panels, you’re going to need a lot of them just to generate enough power to keep stuff warm.

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