Marius Hills (14°N, 56°W) What has intrigued us (Kokh & Dietzler) is the suspicion that the Marius Hills might someday be the Ruhr of the Moon, (its major industrial complex) and make an outstanding site for a major settlement. The

Hills offer:
• Variations in basalt
• Perhaps a good number of intact lavatubes
• Possible or likely pockets of unreleased volcanic volatiles that could change the prognosis for industrial development of the Moon

This area appears to have experienced a number of lava/magma flows, each successive flow somewhat different chemically than the one before – layered igneous intrusions, in geological parlance. On Earth, the most significant case is The Bushveld area in South Africa, source of much of that country’s mineral wealth. The reserves of chromium, platinum, palladium, osmium, iridium, rhodium and ruthenium are the world’s largest along with vast quantities of iron, tin, titanium and vanadium. South Africa is second only to the United States in the production of mineral resources.

The elements listed above are essential to a modern industrial complex. If the Lunar Frontier were to rely only on the elements most abundant on the Moon, oxygen, silicon, iron, aluminum, titanium, magnesium, and calcium, the result would be something like late nineteenth century industry, more than an advanced New Stone Age but not much more.

Lunar industry must find, or import at great expense, copper, gold, silver, platinum, zinc, lead, and other metals not well represented in the regolith at large. The Clementine and Lunar Prospector data have yielded helpful maps, but their resolution leaves much to be desired. New orbiters with more sensitive instruments able to detect specific signatures at very high resolution are essential. Prospecting from orbit is extremely cheap in comparison to fielding and supporting a veritable army of human prospectors on the ground! The later will be needed in time, but. they are best used in areas targeted for further ground truth investigation by orbiting chemical sleuths.

Clementine, Lunar Prospector, and Truth in Science

Clementine and Lunar Prospector have clearly shown that the Nearside Mareplex is much richer in iron, titanium, thorium and other useful elements than highland sites. The poles, in contrast, have little of industrial significance beyond the yet to be ground truth qualified and quantified hydrogen enriched permashade areas, and more round-the-month low angle sunlight in mountainous terrain that may be risky to traverse (ever-changing very long ink-black shadows as well as anything but level) with irregular plateaus of eternal sunrise (To use the term eternal sunshine is very misleading.) At the poles, we may find water ice of yet unknown purity and mixture with regolith, and of yet unknown friendliness to mining techniques, and nothing to do with it except waste it as one-time-use rocket fuel. But these same Clementine & Lunar Prospector maps do not tell us where the real prizes are to be found, if anywhere. But looking at topographical and geological characteristics, the Marius Hills area certainly looks intriguing, perhaps even promising.

Questions and More Questions

David writes: study of the impact craters in the region revealed none that had penetrated through to the underlying highland bedrock. So if there are underground chambers, vesicles of volcanic gas, they might be intact.

So much for the “Moon is all homogenized, contains no surprises, the crust is all fractured, gas would have all leaked out” theory that I have come to believe is entirely false. I say this region could be like a volcanic gas field, truly a gold mine for lunans. One can see that there are no giant craters there or fissures in the surface.

Peter: I checked the reports on TLP, transient lunar phenomena which might include leaking gas. This does not seem to be a TLP area, unlike the nearby Aristarchus Plateau, which is the source of many TLP reports. But the major difference is that in the Aristarchus Plateau, we have a major relatively recent impact crater, Aristarchus itself, which has clearly penetrated into the highland crust underlying the basalt flows which formed the plateau.

David: clearly any gas in fractured basalt has already long escaped. I am growing confident that there may be intact pockets of volcanic volatiles in unfractured layers. Ground penetrating radar and landing teams with explosives and sonic sensors like the stuff they use for oil exploration are what we need. What we have to do is create a vision for others to be inspired by.

Volcanic Gases? The Envelope, Please!

On Earth, more than molten rock, thick fire-red lava escapes from the throats of active volcanoes! See: https://volcanoes.usgs.gov/vhp/hazards.html

Volcanic gases are dissolved in molten rock. But as magma rises toward the surface where the pressure is lower, gases held in the melt begin to form tiny bubbles. The increasing volume taken up by gas bubbles makes the magma less dense than the surrounding rock, which may allow the magma to continue its upward journey. Closer to the surface, the bubbles increase in number and size so that the gas volume may exceed the melt volume in the magma, thus creating a magma foam. The rapidly expanding gas bubbles of the foam can lead to explosive eruptions in which the melt is fragmented into pieces of volcanic rock, known as tephra. If the molten rock is not fragmented by explosive activity, a lava flow will be generated.

The most abundant gas typically released into the atmosphere from volcanic systems is water vapor (H₂0), followed by carbon dioxide (C0₂) and sulfur dioxide (S0₂). Volcanoes also release smaller amounts of others gases, including hydrogen sulfide (H₂S), hydrogen (H2), carbon monoxide (CO), hydrogen chloride (HCl), hydrogen fluoride (HF), and helium (He).

Now given that the Moon was apparently formed from material from which any native volatiles had been driven off by heat, we will be most unlikely to find water or water vapor or hydrogen, either alone or in combination.

The Moon is also apparently underoxidized. Even though the regolith and the crust from which it is derived by impact gardening is 45% or so oxygen by weight, in the form of metal oxides and silicates, there is not enough oxygen to have rendered the vast majority of the Moon’s crustal iron into the ferric form, Fe₂O₃ predominant on Earth. The iron we find is predominantly ferrous, FeO, or even pure, not oxidized at all. That leads us to suspect that the fully oxidized forms of carbon and sulfur are also unlikely. Instead of carbon dioxide, we will be lucky to find carbon monoxide. Instead of sulfur dioxide, we will be lucky to find sulfur monoxide. Helium is also unlikely.

As there is enough sulfur, and enough oxygen in the regolith, the presence of SO gas is of no interest. The prize, perhaps the sole prize, as we see it, is pockets of carbon monoxide, CO, which would be most invaluable, both as a handy industrial reagent in itself, and as a source of carbon which is vital to life in all forms, as well as essential in making steel. We may never find enough carbon on the Moon to use profligately in plastics and other synthetics.

Gas pockets may be too small and insignificant in volume to show up as negative mascons, even at highest resolution. Radar designed to ferret out lavatubes might find such pockets. They would have characteristic shapes noticeably different from the long tubular lavatubes. The discovery of substantial carbon monoxide reservoirs on the Moon would rival the discovery of polar permashade ice reserves in brightening the prospects for fuller industrial diversification, and the chances of attaining economic self-sufficiency. We had previously considered the possibility of finding such “lacunae” (to suggest a Latin topographic term) but The Marius Hills are the first site to suggest that “here is a good place to look.”

We have a lot of prospecting homework to do on the Moon before we can be confident that any reestablished human presence on the Moon has a real chance of an open-ended future. Most lunar probes are designed by scientists with things on their minds other than resources. Scratching the itches of scientific curiosity is good. But it is not what we need. This should guide what missions we support.