So You Want to Mine the Moon?
Discussing Space ISRU Economics, Part 2

Congratulations on picking the 2nd biggest rock in cislunar space! There’s lots of stuff there. Most of it can be found much closer to home, of course- the biggest rock in cislunar space is the Earth, and it’s mostly the same resources as on the Moon, and you don’t need a rocket to get there. Also, most of your potential customers are there.

But let’s talk about the exceptions.

First, the resources:

Where the Moon shines (so to speak) is primarily in two materials. One is phosphorous (P), which is about 4 times as abundant (as a proportion of surface availability) on the Moon as on Earth. Phosphorous is a key component of biology, so is important for living things (like you – er, I mean us- humans). The best fertilizers contain P. It’s also a pretty useful material for making cement off Earth. In fact, I did a whole talk about that a few years ago regarding how to 3D print habitats on Mars (where P is five times more than on Earth). Again, useful, but probably only inasmuch as you’re going to use it in situ on the Moon. P supplies on Earth are ostensibly dwindling, because we let our fertilizers run down the drain and out to sea. In reality, Earth has just as much P as it did millions of years ago- it’s just collecting ever more on the ocean floor, kind of like human spacecraft.

The other material that can be found on the Moon more so than Earth is Helium-3. While scarce on Earth, helium-3 (or He-3) is found in relatively high concentrations on the Moon (and on asteroids), deposited by solar wind over millions of years. He-3 is much like the regular He stuff that floats your birthday balloons and makes you sound like Mickey Mouse, except it’s missing a neutron. This not only makes it lighter, but gives it the ability to smash into other fusion reactants with fewer neutron emissions resulting (which means the walls of your reactor don’t become radioactive as fast). Clean and “limitless” fusion energy is still yet to be a reality, but harnessing this potentially prodigious power source could transform the world's energy landscape, offering abundant electricity without contributing to climate change or environmental degradation. Some folks think He-3 is what is driving the current space race to the Moon. While it doesn’t exactly change the basic economics of delta-v, it opens up the possibility of humans exploring distant planets, asteroids, and beyond, by enabling faster and more economical voyages (because faster trips means fewer supplies consumed en route). Closer to Earth, He-3 possesses unique properties that are also beneficial for medical research with magnetic resonance imaging (MRI), and as a tracer gas in scientific experiments. 

So the question is, “Can you get x from the moon for less than cost of getting it from Earth?”

For x=P (or most anything else besides He-3) the answer is: Not even close- at the current cost per kilogram delta-V, which is somewhere in the vicinity of $50k per kg-km/s. Getting to the lunar surface and back requires around 20 km/s round trip delta-V, so you’re looking at a cost of $1M/kg on top of prospecting, mining, and refining. Terrestrial gold is only ballpark $63k/kg; the only terrestrial materials in the $1M/kg category would be Plutonium-238 and Californium-252. By comparison, phosphorous is (at a few dollars per kg) literally dirt cheap enough we still dump it into our dirt. Mining it from the ocean floor will likely be quite a bit cheaper even if we take account of ecologically sound methods that don’t destroy aquatic biomes in the process.

“But,” you point out smugly, “what if I use a mass launcher to fling stuff back towards Earth? Won’t that reduce those transportation costs?”

OK. Flying it on a magic carpet pulled by unicorns could also work. Build it, and we’ll talk. If you think the cost of building a lunar launch system is less than $100B, I’d advise you to stick to the magic carpet/unicorn solution.

For x=He-3 the answer is probably yes, but then you need to have a market demand of greater than $1M/kg, which leads us to…

The customers:

For all its abundance in rocks, the Moon is highly lacking in the most important thing: an economy, which requires customers. You are probably thinking this is because the Moon is short on both air and carbon. While these shortages are real, it is not necessarily true that customers require these two things. For example, there is abundant commercial activity in low Earth orbit (LEO), with customer presence in the form of satellites. No air or carbon required (although imagine how much better it would be with those!). However, there is so far nothing resembling this kind of infrastructure on the Moon.

“Aha!” you say, “what about the US and Chinese and EU efforts to put people on the Moon in the next decade?”

Yes, let’s not forget the UAE and India too. Looking at all these plans and initiatives, I do see several $B worth of rocket expeditions being launched at the Moon along with a few (maybe dozen) astronauts potentially crewing various outposts over the next 20 years. Potentially good business for a few rocket companies and mission integrators, but I really don’t see a viable customer base there based on that. What product could be produced on the Moon that people on Earth will pay for (at $1M/kg)? Or alternatively, what would incentivize living, breathing, carbon-based customers to reside en masse on the Moon? Maybe He-3 mining operations would do it, and that could spur the creation of a mass launching infrastructure to increase throughput. There is a lot riding on fusion energy tech development.  According to the analysis here, at $1B/tonne of He-3 (which is the same as the $1M/kg we previously estimated), the fusion energy cost would be equivalent to a $7 barrel of oil. Again, though, neither this technology nor the infrastructure yet exist!

“OK. What about an information based economy, like we have in LEO?” you ask.

Great question! Duplicating the communications satellite business model on the Moon won’t work so well due to latency (the time signal takes to travel back to Earth), but there is certainly research that can be done on the Moon. Indeed, nuclear research (including fusion) could be a great candidate for the Moon. Astronomic telescope science, and lunar geology are also good candidates, but all pretty much require government funding. In other words, not significantly different than the current Artemis outpost plans.

In LEO, it took 25 years of government satellites to create a commercial satellite economy, and another 25 years of commercial satellites and government space stations to create what is just now starting to be an economic infrastructure in LEO. Once we’ve put a woman’s footprint on the Moon, let’s start the clock for building an economy there, too. Just don’t expect it overnight.

In the meantime, why not mine the material in LEO, where there are both customers and already refined materials?

So  You Want to Be an Asteroid Miner?
Discussing Space ISRU Economics, Part 1