In spite of my interest in the Asteroid Redirect Mission, I’m still a firm believer that the Moon has a major role to play in space settlement. While Mars and Venus (at the cloud level) may have atmospheres more conducive to human colonization, and while some asteroids might have more concentrated mineral wealth, I still think the moon has several advantages that will make it a key part in humanity’s expansion into the solar system, many of which come down to “location, location, location”:
- Many Feasible “Cash-Crops”: For any ongoing settlement, you’re going to need to get some things from earth, even if your ISRU technology and local manufacturing capabilities are really good. Which means you need some way of bringing new money into the colony to pay for services back home. While it is possible that immigration to your colony might be your cash crop, the nice thing about the Moon is that it has several potential cash crops, including:
- Water Mining — As Planetary Resources, MoonEx, and Shackleton Energy like pointing out, water is a very valuable resource both for propulsion and for life support. The lunar poles have enough water to be potentially very interesting. We need more data on how much and how accessible, but I don’t think anyone seriously doubts the Moon as a realistic source of extra-terrestrial water.
- Tourism — Of all the naturally existing off-Earth destinations, the Moon is the only one that is close enough for practical tourism anytime this side of FTL. Even with the fantasy nuclear power plants with power densities high enough to enable VASIMR’s theoretical 40 days to Mars trip, you’re still talking about a round trip measured in several months, which is far too long for most high-net-worth individuals. The Moon is close enough that you could travel there, spend several weeks, and still make it back within a month. The prices aren’t even close to closing yet, but if they ever get low enough for tourism anywhere in the solar system, they’ll get there first on the Moon. This matters, because tourism doesn’t necessarily require tons of industrial infrastructure like some other businesses.
- PGM and Industrial Metal Mining — While the Moon may not on average have as easily accessible or as densely concentrated ores as some metal asteroids, the Moon is an asteroid aggregator, and if “Wingo’s Hypothesis”1 bears out, there is a good possibility of multiple sites of fairly high concentration metal ores that could be accessible.
- Construction Materials — Some of the simplest items to manufacture off-world, after propellant, life support consumables, and raw metals, are structural materials and construction goods. Many of these goods are also of the variety that can easily be shipped off the lunar surface via non-rocket propellantless transportation systems. Contra a lot of claims by the O’neilians, I think that setting out large arrays of solar panels and radiators on the lunar surface will be easier than making large, gossamer, free-space structures, so I am of the opinion that in many cases it will be easier to process raw materials into useful construction material forms on the Moon, and then only do finished assembly in space.
- Sovereign Clients — The Moon is close enough and accessible enough that a wider range of nations could afford lunar operations of some sort (science, experimenting with resource extraction, national prestige, providing services for their citizens operating on the Moon, etc). While right now the traditional model has been that a country has to do the whole lunar transportation “soup to nuts” in order to feel good about itself, this may change as more affordable transportation becomes available. The barrier to entry for a country supporting lunar operations is likely much less than for Mars or Venus (though asteroids might be competitive). Though I should point out, I think Golden Spike’s price point is likely too high to get much traction in the near-term–good idea, but premature, IMO.
- Immigration — If it turns out that lunar hypogravity is enough for stable, relatively healthy, long-duration human existence, I wouldn’t be surprised if you got some people who wanted to move there. At least for a while. If there is enough of this, you might get some money just from supporting people who want to move there permanently.
The nice thing is that while many other locations might be able to tap one or two of these markets, the Moon can tap all five, and possibly more. While asteroid are likely only going to be mining colonies, the Moon has the potential for a much more diverse economy.
- Regular and Frequent Revisit Opportunities: Unlike Mars, Venus, or the Asteroids, where visit opportunities are only every several years, the Moon is reachable very frequently from say a LEO depot–every 7-9 days. And the trip times, even if you go via EML-2 are relatively short–less than three weeks even if you take the powered swingby to EML-2 and the slow trip from EML-2 to the lunar surface. More direct routes are on the order of 3 days or potentially less. This means many things: a) you don’t have to stockpile as many emergency supplies, b) you can react and iterate on settlement technologies much more rapidly2, c) your transportation system can operate in a closer to flow mode than batch mode, d) There is a higher probability of excess capacity on a regular basis for opportunistic travel or cargo, e) you can get more reuses out of your transportation hardware than say a reusable Mars transportation system3. There are probably more benefits I’m not thinking of.
- Much Shorter Travel Times: The longer you spend in-transit, the more mass you have to carry along per person for the journey. While it may be possible to get much of what you need to support life at the destination (be it Mars, the Moon, Venus, or Asteroids), there aren’t convenience stores you can stop at along the way. While you might be able to close the water and air loops on a transport ship, long-duration trips are going to either require a lot of mass for food growing, or more likely a lot of mass for storing food supplies. Also, longer trips usually push you to wanting more space and more accommodations. Just as you can endure a really cramped space on a short subway ride compared to what you would want for a 12 hour trip or a 3 week journey, longer space trips will require more space and more accommodations per person. This is why a lot of the commercial crew companies are aiming for first-day rendezvous–just the transition from less than a day to several days makes a huge difference on what you need to have on-board. And the step function in travel time between the Moon and anywhere else is at least an order of magnitude.
- Close Enough for Some Tele-Operation: Round-trip speed of light latency to the Moon is only ~2.6s. Interestingly this isn’t that much worse than comms latency to ISS via the TDRSS relay satellites. As the latest FISO telecon points out, this isn’t good for dextrous manipulation tasks (which become really, really slow), but it is fine for many lower-dexterity tasks, enabling at least some level of earth-based teleoperations. I don’t think it will be good enough to “just send the robots and let them set everything up first” like some people think. But it may be enough to offload at lest some tasks, and augment the humans who do go at first. 3s latencies are worlds better than 10s of minutes as far as what you can get done.
- Psychologically Close to Earth: I don’t know how much weight I’d put on this one, but someone living on the Moon isn’t anywhere near as remote from Earth as someone on Mars, Venus, or the Asteroids. For one, if you’re on the near-side you’ll always be able to see the “green hills of earth” from a distance. So long as the hypogravity effects are reversible, there’s more realistic hope of going home if you ever decide you’re done with the Moon, and just having that option is probably comforting to many. You’re close enough to Earth that you’re still effectively inside the Earth’s local area network so to speak. You can still have phone conversations of some sort with home. You can still effectively use the internet without requiring a local copy. You can still easily transact business with people on Earth without really long latencies. There may be some drawbacks to this too, but the Moon is always going to feel like it’s more part of Earth’s economic sphere than anywhere outside of cislunar space.
- Relatively Easy Access Back to LEO and Earth: While a lot of say asteroid mining aficionados4 like to point out how easy it is to get back from a few cherry-picked asteroids, relative to the Moon, the Moon isn’t that hard to get back to Earth from. Due to its lack of atmosphere, there’s actually a range of propellantless methods for getting off the Moon, with several of them potentially low-enough acceleration that even people could use them5. There aren’t as many propellantless methods for getting things gently to the ground that aren’t super scary in one way or another, but there are some. Most of them require a decent amount of infrastructure, but once they’re there, the Moon will be substantially easier to get materials back from than anywhere else in the Solar System. Asteroids might still win on resource concentration and ease of extraction (maybe), but the Moon will win hands down once you have or more of those “railroads” built.
So while I cheered when Constellation was canceled, and am somewhat skeptical (in a friendly way) toward current lunar initiatives such as MoonEx, Shackleton, and Golden Spike, and while I’m not at all a fan of most of our Congresspeople’s attempts at rebooting Constellation as a Huntsville/Michoud/Promontory makework scheme to send as few astronauts to the Moon as possible for as much money spent in as many key Congressional districts as possible, I’m still very much a fan of the Moon. I think that our best days are ahead of us, that we haven’t “been there, done that”, and that in fact the Moon is likely going to be one of the most important parts of our expanding economic sphere over the coming half century at least.
Latest posts by Jonathan Goff (see all)
- NASA’s Selection of the Blue Moon Lander for Artemis V - May 25, 2023
- Fill ‘er Up: New AIAA Aerospace America Article on Propellant Depots - September 2, 2022
- Independent Perspectives on Cislunar Depotization - August 26, 2022
- See Dennis’s hypothesis about there being easily accessible Nickel-Iron asteroids nearly intact on or near the lunar surface that he explained in Moonrush: Improving Life on Earth with the Moon’s Resources.
- i.e. if an ISRU technology turns out not to work, you can ship a next generation system very soon, not having to wait for years or rely only on what you can cobble together on-site
- Just as the key to low-cost earth-to-orbit RLV transportation is the number of reuses and the frequency of reuses, the same applies to in-space RLVs
- Note: I almost count myself as one of them–I may be a Moon-firster, but that doesn’t mean I don’t value or appreciate the rest of our Solar System or think that they don’t also have major roles to play
- Yes, yes, I need to finish my “Slings and Arrows of Outrageous Lunar Transportation Schemes” series.