Introduction

This video was produced by Isaac Arthur.$$^{[1]}$$

An important first destination for human travelers is the Moon. The Moon is a prelude to the exploration of other worlds. By living and building villages and perhaps even expansive cities on the Moon, we will have gained valuable experience when we set out to colonize the next world. Michio Kaku in Physics of the Future argued that we could build an immense array of lasers on the lunar surface which could be used to beam future, solar sail, starships to far off star systems. The Moon is rich and plentiful in resources which could be extracted and used for rocket fuel or the "nuclear reactors of tomorrow." Not only will the Moon give us “practice” at learning how to colonize other worlds, not only will it function as a kind of “solar gas stations” for providing energy to future spaceships, but it will also give us the opportunity to “peer” deeper into the universe than ever would be possible using Earth-based telescopes. The Moon offers one of the quietest and most tranquil places in the solar system for doing radio astronomy; this will allow us to use radio-astronomy to study the universe without an atmosphere and electromagnetic perturbations.

Finding a good spot to set up shop

The place here on Earth which most closely resembles the harsh conditions and environments of the Moon is the South Pole. Both of these alien landscapes are absolutely dry and baron—not a cricket or blade of grass. They resemble vast deserts with temperatures dropping below minus 100 degrees Fahrenheit—though in the case of the Moon, temperatures sometimes soar beyond 200 degrees Fahrenheit. Most regions of the Moon experience a full lunar day where they are periodically bathed in intensely hot sunlight for two weeks and drenched in extremely cold darkness for two weeks. Since the Moon doesn’t have any atmosphere, when these lunar regions are facing the Sun they get bathed in unfiltered sunlight containing a lot of ultraviolet radiation. This causes temperatures to soar over two-hundred degrees Fahrenheit. The other side of the Moon is completely dark since all sunlight gets blocked by the Moon’s opposite side—on this dark side of the Moon, temperatures fall below minus two hundred degrees Fahrenheit. To complicate matters even more, the Moon is perpetually bombarded with micrometeorites and radiation from the Sun and other distant objects in space. The Moon seems absolutely inhospitable to life.

The first challenge we must overcome to establish a human colony on the Moon is to find locations which do not experience the “lunar day” since all such locations experience extreme hotness and coldness. To get around this problem, we can go to the North and/or South poles of the Moon. These locations are perpetually grazed by low-intensity sunlight and remain at a more or less uniform temperature that is neither extremely hot nor extremely cold. With this in mind, despite not having a specific location picked out yet, we do have a general idea of where we want to colonize: one or both sides of the lunar poles. This solves the problem of extreme temperatures, but how do we get around the problem of micrometeorites and cosmic radiation. The short answer is by building infrastructure and living habitats in deep lunar pits and craters, and then covering them with Moon rock and regolith (which is essentially just the Moon dust). Let’s discuss how the precise locations of pits and craters along the lunar poles were obtained; then we’ll discuss what the advantage is of living within such places are.

The planetary geologist Mark Robinson analyzed images obtained by the Lunar Reconnaissance Orbiter and discovered pits with rock overhangs$$^{[2]}$$. Dangerous sunlight would graze across the upper rim of these pits leaving the depths of the pits untouched by any light and in eternal shadows$$^{[3]}$$. This coverage would shield some of the cosmic radiation$$^{[4]}$$ and, as an additional perk, it would also offer thermal insulation which would make it easier (more specifically, less energy would be required) to keep living habitats at a comfortable temperature. Not only does the Moon have pits and craters to offer shielding from cosmic radiation and thermal insulation, but the Moon also has lava tubes (which are basically like caves) which also offer thermal insulation and protection from cosmic radiation. So pits, craters, and lava tubes would be ideal places to live (although they are not 100% necessary). In addition to this, as we’ll discuss in more detail, we can also use lunar regolith to 3D-print a protective covering over infrastructure to provide even more shielding. Once a living habitat is covered by lunar rock and regolith, all of that shielding means that it is not necessary to use very thick, massive, and heavy surfaces to make the habitat—that is only necessary when the infrastructure is covered by little or no lunar rock. In these ideal locations (i.e. craters and lava tubes) we can use a comparatively thin, unmassive, and lightweight surfaces and materials to construct living habitats (and other infrastructure). Therefore, when we send a living module from Earth’s surface to the Moon, less work (and hence energy) is necessary to escape Earth’s gravity well to get to the Moon. This is nice since we want to ephemeralize as much as possible in all industrial activities.

The Lunar Reconnaissance Orbiter has confirmed the existence of frozen water along the bottoms of these pits and craters. When I learned about this, the first question that came to my mind was: how did the water get there? The answer is that asteroids and comets—containing frozen water—are constantly colliding with the lunar surface and depositing that water. On regions of the Moon which are not at the lunar poles, any deposited water (say, for example, frozen water was deposited on the “dark side” of the Moon not getting any sunlight) eventually gets evaporated by the super energetic, unfiltered sunlight. However, any water which gets deposited into the depths of pits or craters along the lunar poles will remain frozen basically forever (as long as the Moon is alive) since those regions never get any sunlight. This is very good news if we’re living in one of these special regions along the lunar poles because water is an essential ingredient needed to perform many important (indeed, many essential) industrial processes on the Moon such as: growing plants for food, producing air to fill human habitats with, and to produce hydrogen for rocket fuel. To clarify those last two items, once we extract the water, then we are able to perform electrolysis to break the water molecules into its constituent atoms—namely, oxygen and hydrogen. The former can then be used to inflate living modules (or maybe something much bigger like a lunar hotel) with air and the latter can be used as rocket fuel.

So far I have told you that these “special lunar locations” have uniform and non-extreme temperatures; they offer coverage from micrometeorites and cosmic rays; and they have frozen water. But let’s now discuss some of the important remaining ingredients we haven’t covered yet which would allow us to 3D-print infrastructure (buildings, transportation systems, etc.) using only the materials on the Moon and which would allow us to power future nuclear reactors, if they are ever developed. The Moon is not only a stepping stone to travel to other places due to its presence of water and the ability to send a modest station and habitat module there, but it turns out that the Moon’s abundance of many other important resources (i.e. iron, magnesium, Helium-3, cobalt, etc.) would allow us to 3D-print (using just the materials on the Moon) lunar villages and sustain a very, long-term, human presence.

The Moon is a veritable treasure trove containing, as previously mentioned, water for drink and growing food, iron and other metals for building infrastructure, and, perhaps best of all, Helium-3 which could be used to power the nuclear reactors of tomorrow. According to one estimate, the amount of Helium-3 ejected by the Sun and deposited into the lunar surface is over 1.1 million tons$$^{[5]}$$. To put that into perspective, it has been estimated that a mere 100 tons of the stuff could power the Earth for an entire year. Since all of the Helium-3 is deposited in the first few meters of lunar top soil, this mean that extracting it wouldn’t be very difficult. If we ever make a self-sustaining nuclear reactor, this treasure trove of Helium-3 (combined with the possibility that we might have two expansive solar farms on both sides of the Moon as well which we'll discuss later) would be a game changer for two reason: it would allow us to power an immense global infrastructure spanning the entire lunar surface; and all of that energy could be beamed to solar sail, spacecraft. Such spacecraft—capable of reaching speeds which exceed 20% light speed—would be the first generation of interstellar star ships.

Moon villages and cities

This video was produced by the European Space Agency, ESA.$$^{[6]}$$

The European Space Agency (ESA), in a collaborative venture with the architectural group Fosters+Partners, have released a video of their ambitious plan to send a spaceship (containing a light-weight, deployable, living module) to the Shackleton crater at the lunar South pole. The Shackleton crater is a colossal hole—it is a little less than twice as deep as the Grand Canyon. Because hostile sunlight merely grazes the rim of this crater, within the local vicinity of this crater there are regions of eternal light and dark—spots always covered by sunlight (along the rim) and other spots always engulfed in shadows (within the depths of the crater). The Shackleton crater would be an ideal place for space travelers to set up shop and build a lunar village. Here, the temperature stays more or less uniform; another upshot is that the lunar rovers need only take a short excursion to the depths of the crater to mine and extract water. Once the lunar lander lands on the Moon’s surface, it would automatically use its “metallic arms” to set the habitat capsule on the ground. After that, the habitat capsule would automatically inflate into a scaffold membrane whose appearance resembles that of some kind of blimp. Then, after that, the lunar rovers use their scoops to shovel regolith (Moon dust), then they move the regolith and place it beside the inflated habitat, and finally, for the next 3 months, use the regolith—like an artist would use paint—to 3D-print layers of regolith and rock over the external surface of the living habitat. The end result is that the habitats are covered by a kind of shield which blocks harmful micrometeorites and radiation from penetrating the habitat.

In addition to a Moon village, it is necessary that human settlers have a sustainable, self-sufficient greenhouse for a source of food. The plants would receive energy from ultra-energy efficient LED light sources. The LEDs would be appropriately modulated in order to emulate the conditions here on Earth. The LED light befallen on the plants would provide them abundant energy which they’ll use to undergo photosynthesis. This would allow them to convert carbon dioxide exhaled by human travelers into oxygen—an essential element for the existence of all human life. The lunar regolith contains all the raw ingredients necessary for a robot to make solar cells to power those LEDs. But, perhaps, these 3D-printed solar cells could do much more; perhaps they could power a lunar village like the one proposed by ESA and Fosters+Partners or maybe something vastly greater and more expansive.

Source$$^{[7]}$$

The ambitious vision of the physicist David Criswell is to have many of these robotic rovers on both ends of the Moon, themselves powered by sunlight, 3D-printing hectares of solar cells and beam it back to the Earth in the form of microwaves to power the world$$^{[8]}$$. However, as I discussed in my article on the colonization of the asteroids and the comets, by using an economic system based on sustaining the dynamic equilibrium of planetary resources, the planet Earth could provide an abundance of resources and energy to earthlings for billions of years. What, then, are the Moon explorers left to do with such an abundance of energy? They would use it to construct a beautiful and magnificent lunar city containing immense, habitable, dome-like structures. Some of them would be lunar hotels containing grassy and lush recreational centers. Humans could jump from a diving board from an extraordinary altitude (several times higher than the highest Earth-based diving platform) and descend into the hotel pool; or strap on a pair of wings and fly as long ago envisioned by Leonardo di Vinci$$^{1}$$. We could also build mega-domes in which humans play sports—but sports would be quite different on the Moon which has only one-sixth the gravity of that of Earth. The magnificence of a lunar city which could be realizable through human ingenuity is difficult to capture in mere words; I therefore turn to the arts (see gallery below) to present possible infrastructure in a futurist lunar city which is or might one day be possible.

Lunar Mass Driver

The physicist Gerrard K. O'Neil imagined that at some time in the future, we humans will build a base on the Moon which would incorporate a linear-mass accelerator (also called a launch loop or mass driver) such as the one depicted in the image above. If you look at the left of this image, you can see a tiny vehicle scuffling along the lunar surface. This is an artist's depiction of a vehicle scooping up loose lunar regolith; that regolith is then transported to the mass driver (in the middle of the image). After that, the regolith is sealed inside of a pod as a payload; this payload then gets accelerated down the long track of the mass driver. The payload would "hover" above the surface of the track (it would be in "mid air," so to speak) due to a magnetic field acting on that payload so as to keep it above the "ground." This allows the payload to "float" eliminating any ground friction and, since there is no air on the Moon, the payload wouldn't experience any sort of air friction. This would enable the payload to be accelerated to extraordinary speeds. The mass driver would accelerate that payload down the length of the track and launch it into space. That payload would be hurled to a very particular location in space called the Earth-Moon Lagrange-2 (L2) point. A mass catcher would utilize chemical attraction to "catch" the payload as it flies to L2; the lunar regolith would then be processed by a chemical planet orbiting the Moon at L2 (the mass catcher is attached to the chemical planet). The chemical planet would process the lunar regolith into materials necessary to manufacture ceramics, glass, metals, water, and carbon dioxide.

If we allowed a storage unit containing these processed materials to freely fall from L2, it would move along the trajectory depicted in the image on the right until it fell into orbit around the Earth at an altitude of 100,000 to 200,000 kilometers above the Earth. This orbit would be an ideal location to build the first space habitats using that processed lunar materials. This entire scheme I have just described, despite not being exactly what O'Neil had in mind, more or less encapsulates the basic idea of what he wanted to do: build a mass driver on the Moon, hurl lunar materials into space, and use that material to build an O'Neil cylinder. This scheme is doable today and it would allow us to build an O'Neil cylinder in space while avoiding the high costs associated with sending things from Earth to space. Other necessary materials for the construction of the O'Neil cylinder could be acquired from mining asteroids. Mining asteroids is something which a few private companies want to do by the 2030s and, it is my view, that sometime during the mid-21st century we will be routinely moving and mining asteroids for their materials. Building the first space colony, whether it be an O'Neil cylinder, or Bernal sphere, or Standford torus, or some other design, will extend humanities tradition of building cities and settlements along lanes of commerce and trade.

Though everything which we have discussed about humans colonizing the Moon would be totally possible, we probably wouldn't want to do that. Instead, it is most likely that we will build bases on the Moon, have robots carry out mining operations, and also conduct research there. That's not to say that we humans will never set foot on the Moon again (something which I do foresee happening), but rather that it isn't a place which we will likely live on permanently or for extremely long durations. Artificial worlds like the O'Neil cylinder (and other options which we discuss in greater detail in other articles) would be a much better option.

References

1. Issac Arthur. "Industrializing the Moon". Online video clip. YouTube. YouTube, 18 May 2017. Web. 18 May 2017.

2. Hendrix, Amanda, and, Wohlforth, Charles. Beyond Earth: Our path to a New Home in the Planets: Pantheon, 2016. Print.

3. NASA Goddard. "NASA | The Moon's Permanently Shadowed Regions". Online video clip. YouTube. YouTube, 06 March 2013. Web. 05 May 2017.

5. Barnatt, Christopher. “Resources from Space: Mining the Moon”. Explaining the Future, Christopher Barnatt, April 24 2017, http://www.explainingthefuture.com/resources_from_space.html.

6. European Space Agency, ESA. "3D-printing a lunar base". Online video clip. YouTube. YouTube, 06 November 2014. Web. 05 May 2017.

7. The Documentary Network. "Earthlight - Learning to live on the moon PBS Documentary". Online video clip. YouTube. YouTube, 13 August 2014. Web. 05 May 2017.

8. stevebd1. "Living on the Moon Clip 3". Online video clip. YouTube. YouTube, 12 November 2010. Web. 05 May 2017.

9. “New Images Offer Sharper Views of Apollo Sites | NASA”. NASA, November 25 2015, https://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html.

Further studying

1. Woerner, Jan. “MOON VILLAGE: A VISION FOR GLOBAL COOPERATION AND SPACE 4.0”. Jan Woerner's Blog, Jan Woerner, November 23 2016.

2. Fecht, Sarah. "Popular Science We Could Be Living On The Moon In 10 Years Or Less
And it wouldn't actually be that expensive, thanks to robots, 3D printing, and SpaceX
". Popular Science, Sarah Fecht, March 10 2016.

3. LaRouchePAC Videos. "Krafft Ehricke: “Lunar Industrialization & Settlement—Birth of Polyglobal Civilization”". Online video clip. YouTube. YouTube, 27 January 2017. Web. 05 May 2017.

4. ADVEXON TV. "Will We Live On The Moon? - Full Documentary HD HD". Online video clip. YouTube. YouTube, 02 May 2015. Web. 05 May 2017.

5. SciShow Space. "Building a Base on the Moon". Online video clip. YouTube. YouTube, 01 April 2016. Web. 05 May 2017.

6. McCullough, Edward. “Shackleton Dome: Is a Domed Lunar City Possible?”. National Space Society, Edward McCullough, Number 4, 2008, http://www.nss.org/settlement/moon/shackleton.html.

Notes

1. Click to see a video clip (taken from episode entitled 'Living on the Moon' broadcasted July 09 on the National Geographic channel) of what such a futuristic lunar hotel might look like.