Typical design for a lunar mining outpost.

New to the series? You might want to start with Part 1!

Welcome to Part 4 of my Cislunar Economy series! First, I want to thank all of you for making Part 3 such a huge success. If you like this series, please share it, and remember to follow myself and the function(core) publication on Medium.

In Part 3, I introduced my framework for the 11 Cislunar verticals. The framework attempts to bring clarity into the upcoming Cislunar Economy by dividing the potential activities according to which market niche they serve. This procedure achieves two goals:

Each vertical can now be analyzed separately, providing insight into its value chain, market size, etc. It’s now easier to map the relationships between verticals, making it easier to spot technical commonalities, common requirements, interdependencies, and so on.

With this in mind, the first step is to begin studying the different verticals in depth. The following parts of the series will do precisely that, and I’ll describe the activities inside each vertical, the potential markets, and why I divided things in this manner. I’ll begin with the mining verticals: water mining, and metal mining.

Making sense of space mining

Space mining is often presented as the next gold rush. That is a fairly good analogy, but it is also a very broad generalization, and likely looks too far into the future: the point where we’ll be able to mine the totality of the trillion-dollar worth of platinum in this asteroid is relatively far away. Also, not all that glitters is space gold.

As discussed in Part 2, the most interesting resources in space (at least in the near future) will be water, structural metals, and semiconductors. From a market perspective, it makes sense to separate these into two different verticals: water mining, serving mainly the propellant market, and metal mining, serving the manufacturing market.

Let’s see how this works.

Water’s space magic

Water is the Holy Grail when it comes to space: for commerce and settlement, it can provide propellant, radiation shielding, crew consumables, and even cooling fluid. For science, it can serve as an indicator for a potentially habitable environment. Water is the first thing everyone looks for in space, and we’re lucky to have found it a-plenty in many celestial bodies: Moon, Mars, asteroids, several moons of Jupiter and Saturn; even Pluto has mountains made of solid water. Granted, it’s never as readily available as Earth’s surface oceans, but the water is there, and we can use it for our purposes.

In our Cislunar Economy, water will come from two sources: asteroids and the Moon. These sources will then compete in two markets:

The propellant market, providing propellant to orbital and lunar depots.

The consumables market, providing crewed spacecraft and stations with water and oxygen, radiation shielding, and potentially even cooling fluid.

Of these two, propellant will be by far the most lucrative. Considering current low-end launch prices (Falcon Heavy), propellant requirements for LEO-GEO transfer of commercial GEO satellites at current launch rates would be around $1.8B per year for a LOx/LH2 space tug like ULA’s ACES (if people decided to use a space tug from LEO instead of a direct launch). That market could roughly double if space agencies started implementing lunar bases or Mars architectures that benefit from on-orbit propellant (examples are the Evolvable Lunar Architecture and NASA’s Mars Design Reference Architecture 5.0).

Compared to this, consumables would be around $30M per year for a commercial space station and a crewed mission to Mars at every launch opportunity. A good thing to have, and an enabling capability for some human missions, but a side-project for miners.

Given the size of the potential market, it is unclear which provider will prevail: the Moon or the asteroids. There is an important uncertainty regarding the investment requirements and operational costs of mining lunar ice versus asteroid water, essentially because of uncertainty around technical requirements. There are certainly very detailed proposals out there, such as the APIS architecture from TransAstra, but we have companies betting on both sides. Among others, ispace, MoonEx, and Shackleton Energy are betting on the Moon, while Deep Space Industries, Planetary Resources, and TransAstra are betting on asteroids.

There are several basic arguments for both sides:

Asteroids require less propellant to reach (a cost reduction), and reduced gravity environments would, in principle, allow for easier infrastructure: the same spacecraft could reach the asteroid, extract water, and haul it back. Water may also be easier to extract from asteroids than from the Moon: just bag the asteroid and heat it up. However, asteroids are farther from the Earth than the Moon, requiring more complex operations, more autonomy on the spacecraft, and longer round trips, meaning a less-constant supply. We also have little knowledge about the physical structure of asteroids; they likely range from solid rocks to lightly-bound rubble piles, which would add several constraints and requirements to the spacecraft, adding extra cost.

The Moon has higher propellant requirements to get to, and you’d burn a significant portion of your product to get it to orbit. More infrastructure, such as landers, mining equipment, and haulers, would be required. You’d also run into problems with operating in shadowed environments, and we’re unsure about the state of the water we’ve found (is it ice? Ice-mixed with regolith? Water-rich minerals?). However, the Moon is just around the corner, making it easier to reach, and you could even have humans operating the equipment in real time (either in person or through teleoperations). We have experience with rovers and landers on the Moon, so we are sure we can build those, while the uncertainty over the structure of asteroids will likely increase spacecraft cost.

Pros and cons of Moon versus asteroids for water production.

All in all, the number of pros and cons for each supplier essentially guarantees that they will compete on relatively equal terms: they both have the potential to reach a competitive price point (currently considered to be around $10,000/kg of water), at least when factoring in location, as lunar propellant will be cheaper on the lunar surface than asteroid propellant.

Especially at the beginning, the differences derived from resource location will have a significant impact on cost. Whoever has first-mover advantage will hog the market, but depending on the nature of demand, lunar propellant might be able to take over asteroid propellant, or even to compete at a higher price. For example, if market demand requires a constant flow of new propellant, asteroid miners won’t be able to keep up with demand, unless they haul enough propellant on each trip. In that case, lunar propellant would compete at a higher price, and we might see asteroid miners move on to extract metals and use any propellant from the asteroids for themselves. However, if the demand only requires a build-up of propellant reserves in orbit for a large one-time expenditure (say, a crewed mission to Mars), asteroids might have the upper-hand against the Moon (although in this case they might have to compete with Earth propellant as well, depending on which launch vehicles we develop).

In summary, there will probably be enough market for both asteroids and the Moon to produce propellant. The Moon will likely supply clients that require more constant trips (crewed trips in Cislunar space and lunar landers), while asteroids will provide cheaper propellant for low-frequency missions and for stations further from the Moon, since when coming from outside the Earth-Moon system, propellant requirements are very similar for most destinations.

In the long term, though, we’ll probably see a different scenario: as asteroid miners build enough infrastructure to guarantee a constant supply of propellant, lunar miners will be limited to suppling the lunar surface and to covering over-demand in stations near the Moon. Asteroid miners on the other hand will probably supply propellant to anywhere that is not LEO, where it might be affordable to ship it up from Earth (with reusable launchers, specially SpaceX’s ITS).

Lucky for all of them, there is not only water to mine.

Metal mining

“Structural metals” is a broad term that includes resources from ferrous metals to titanium and aluminum, depending on the source and application. However, there are two main reasons to group them into the same vertical: they’ll serve the same market (manufacturing), and they’ll have similar extraction and beneficiation techniques.

Defining “manufacturing” as a market might seem too broad for Earth, but things are different in space. Short term, we won’t be manufacturing that many components, given the lack of infrastructure in orbit or the lunar surface. We’ll mostly focus on simple components: antennas, trusses and other structures, and eventually solar panels. We’ll also work primarily with 3D printing and extrusion, which works similarly with these metals.

Given these limitations, the market will be fairly small, and it makes sense to group all the activities together. These components can be manufactured with metals available both in asteroids and the Moon. The main difference is that for lunar structures, landers, and other spacecraft we might use titanium, which is widely available on the Moon, while for orbital structures (which mostly require a good tensile strength) we might decide to go with asteroid-derived ferrous metals due to their high availability and easy extraction, for example to build structures out of iron whiskers.

As for extraction and beneficiation, things are not as straightforward for metal as they are for water. Iron, cobalt, and nickel could easily be extracted with the carbonyl process. Other metals, such as titanium and aluminum, require higher energies, due to higher stability of the oxides they form. Several processes have been proposed for this, from hydrogen reduction to electrolysis of molten regolith. All of these require extra steps, in the form of regolith beneficiation prior to the separation of the metals. For this reason, my favorite process for metal extraction is Landis’ fluorination, which requires no prior beneficiation. The whole process acts as a regolith digestion system, getting raw lunar (or asteroid) material on one side and spewing metals out of the other. In any case, most processes are similar to each other, requiring the separation of a metal from its oxide, either via reduction or electrolysis.

With so many options, which is the winning one? Well, it will depend on many factors, but mainly on the abundance of the metal and the cost of deploying the equipment. The latter will in turn be influenced by the appearance of on-orbit propellant from water, which will reduce costs and probably make more energy-demanding, but efficient, methods interesting for the industry.

In the current situation, we have very little idea of how the space manufacturing market will evolve, and manufacturing will be the main customer of metal mining (we’ll bring some precious metals back, but not that many). We know we’ll build small components, but just that.

What about lunar habitats? Current plans mostly use raw regolith, but you could argue that they are forced to work with what they have. What about orbital stations? Or huge satellites platforms? Or crewed spacecraft? We are constrained in our thinking by what we currently have, and that is spacecraft that fit inside a rocket fairing and have a certain configuration that works with building everything from Earth.

The availability of metals in space will allow many new concepts of spacecraft to appear that so far have been considered only as the product of dreams (or very expensive state-sponsored projects). We are already seeing some interesting ideas, but concepts for this market will explode as soon as the resources become available.

Metal mining will change space manufacturing forever, and that’s exactly the next vertical we’ll analyze: on-orbit manufacturing.