The Waning of the Moon

Humanity is on the verge of taking the first step towards becoming a spacefaring civilisation – and yet we run the very real risk of stumbling. The effort of NASA is bearing down on the Artemis program, with the rest of the aerospace community falling in line. All eyes are trained on the next 10 years of development of the Moon. But – if we are unlucky, or one of our many assumptions fails – we will find our arrival a hollow victory. For we are just a few mis-steps or misunderstandings away from wasting a tremendous amount of effort. The apparent rise of the Moon could very easily turn into a twilight.

Before I reach the main line of reasoning, a few words about the way in which we’re returning to the Moon. The current drive of the Artemis program does not lack in boldness or canny decision making – the selection of Starship for HLS, and the entire CLPS program evidence that. But the entire program is hamstrung by the architectural decisions thrust upon it by politics and history. No sane planner would look at the state of technology today and decide to place Gateway in such a high lunar orbit, or depend on a single, over-budget, behind schedule vehicle. Nor would they select a landing site and potential site of future settlement based on such a staggering lack of information.

For this is the real issue with the planned return to the Moon. As excitement builds so do grand future plans of resource extraction, propellant production, mass drivers and all manner of toys. All depend on a single fundamental assumption – that extraction and processing of basic lunar resources will be relatively cheap and easy. And that assumption is not just unverified, there’s substantial reason to believe it may be outright false. If that comes to pass we will find almost all our effort wasted and Artemis will be demoted to the flags-and-footprints mission it wants to desperately avoid.

Let’s start with water and propellant. Likely the first resource that will be tapped in any extra planetary settlement will be whatever source of water is available for the purposes of propellant production. In the case of the Moon that source is the enormous proven ice reserves in the permanently shadowed regions (deep craters which never see sunlight, so the ice remains unmelted). This is a source of huge excitement for advocates of lunar exploration, who point to a future where hydrolox propellant can be manufactured in huge volumes in situ. This is an argument that conveniently ignores the data from the LCROSS orbiter/impactor which found an ice concentration of around 5% in the immediate surface regolith. Plus the evidence from Chandrayan-1 which indicates the majority of exposed ice consists of small pebble-sized pieces. That’s an extremely far cry from an easily exploited glacial deposit as we know to exist on Mars. It will require a hugely complex mining process comparable to ore quarries on Earth – all whilst withstanding temperatures of 100K, the challenging lunar dust environment and handling the enormous quantities of overburden and waste material produced.

Mosaic of the Lunar south pole, compiled from Lunar Reconnaissance Orbiter imagery. Image credit: NASA/GSFC/Arizona State University

The same argument more or less follows for the extraction of lunar metals. There’s a lot of excitement about the use of lunar metals both on the surface itself, and in space around the Moon and Earth. The issues lie in both the extraction and refining of those metals. In short, the Moon is a really awful place to do metal mining. On Earth and Mars (and presumably Venus and Titan too) there’s been a few billenia of geologic and hydrologic processes to alter the landscape and, critically, concentrate particular minerals. In comparison the Moon, and other small airless bodies, have been barely geologically altered since their formation. There’s been cratering and surface churn, plus some localised volcanism, but nothing to move particular minerals through the bulk crust. The Moon’s surface is remarkably homogeneous compared to the other celestial bodies we know. The result: we can’t do terrestrial-style mining where an ore body is located with metal concentration factors above the surrounding rock. You have to do an exhaustive regolith crawl, or some manner of total conversion. Just like water extraction – it’s mechanically challenging, energy-intensive and just outright difficult to get metals from the Moon.

It’s also worth saying a word for the long term prospects of the Moon. In principle there’s nothing wrong with the core ideas of the lunar mass driver and orbital refining to produce O’Neill cylinders. The issue is they’re just that – ideas. For some of them, i.e., launching lunar ice to orbit for use in propellant manufacture, the physics and technicalities seem to be plausible in a 50 year timeline. For others vapourware would be a generous description. Some talk about helium-3 like it’s extremely abundant and it’s useful immediately. In reality it occurs in parts-per-billion at best and requires mature high-temperature fusion technology to even be viable. If we’re lucky and develop substantially faster than expected, we might be able to start planning for extraction within a century. I’m not placing any bets on it.

Gene Cernan on the Moon during Apollo 17
Gene Cernan, coated in a fine layer of lunar dust. Image credit Harrison Schmitt / NASA

This is the overall kicker when it comes to the Moon. The future that’s promised is basically predicated on a number of risky assumptions about the immediate availability of resources on the surface. Without that, all the known problems with the Moon start to look a lot more serious. Away from a tiny number of locations the nights are two weeks long and cryogenically cold. The availability of solar power at the south poles is most certainly poor. The issues with dust abrasion and ingress through equipment are severe and hard to mitigate. And critically, many of the technologies needed to mitigate these issues aren’t especially applicable in the rest of the solar system. Some of it is, ECLSS works everywhere, but the materials and power requirements of a lunar base are so different to deep space or Mars that it often makes sense to consider them as a different genus of system.

This is how the Moon could be a stumbling block for us. If our critical assumptions fail then the rest of the whole, bold future topples like a Jenga tower. In an ideal world, if that starts to happen we will cut our losses and have a deep think about how best to proceed. We don’t live in that world. It’s far more likely that good money will be thrown after bad, sunk cost fallacy will begin to kick in and billions that could be better spent on Mars will be poured onto the lunar surface. At the moment we should be boldest and stepping outwards, we will instead stumble back and the apparent rise of the Moon will turn into a deepening twilight.

Illustration of Artemis astronauts on the Moon
Image credit NASA

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