The question was asked more than half a century ago and is relevant again now, as the Americans and Chinese prepare to return to the Earth’s only natural satellite. Why go back? The two powers do so, this time, with the intention of staying for longer stays than the brief visits of the first astronauts in the 60s and 70s. The geopolitical interest in this race is indisputable.
But there are more reasons. As always, the desire, implicit in human nature, to always go a little further. The reason George Mallory gave for attempting to climb Everest is famous: “Because it is there.” Perhaps that same reason could partly justify the epic of the first Apollo flights, but today that sense of adventure has evaporated to make way for more prosaic motivations.
The Moon is an excellent scientific laboratory. That may be another justification for new explorers. There are still many unknowns to clear up about its origin, its evolution and with it, that of the first times of the solar system. The absence of atmosphere and magnetic field offers very special conditions for carrying out astronomical observations from its surface. And the far side would be a perfect place to install radio telescopes, safe from electromagnetic disturbances generated on Earth. Of course, simple scientific curiosity may not justify the enormous cost of the undertaking.
There remains another more material motivation: commercial interest. Is there something of value on the Moon that makes it commercially interesting? An obvious answer is water. Of course, in most of the satellite its existence – solid or liquid – is impossible: in a vacuum and in the heat of the day, any ice sheet would sublimate and the gases would escape into space.
Ice in dark craters
But in the polar regions the situation is different. Unlike on Earth, the Moon’s orbit and axis are very slightly inclined with respect to the ecliptic. There are almost no stations there. At the poles, the Sun’s rays always hit very tangentially and do not reach the bottom of some deep craters. Plunged into an eternal night, temperatures are recorded there that never rise above 150 degrees below zero, enough to allow the indefinite conservation of ice.
Several experiments have confirmed the existence of water ice. Some satellites have detected it by analyzing neutrons caused by the bombardment of cosmic rays, a symptom that points to the presence of hydrogen atoms embedded in the regolith. Not necessarily as water, but also as hydrated mineral constituents. Others have used the “bistatic radar” technique: sending a radio signal that bounces off the bottom of these craters to be picked up by large tracking antennas on Earth. The distortion suffered by the waves was more typical of icy surfaces than of rocky terrain.
It is estimated that in the southern region of the Moon there are about 10,000 square kilometers of permanently shadowed areas. In them, the ice does not form large extensions like skating rinks, but is mixed with the regolith in a kind of frozen mud. In proportion, from each cubic meter of land the equivalent of a can of water could be extracted, in the best of cases.
If lunar water is ever obtained, it will not be destined for human consumption or to be sent to Earth. Even purified, it will most likely have an unpleasant taste and, on the other hand, we already have plenty of water on our planet. Its true use will be as raw material to decompose it into oxygen and hydrogen, which are one of the most energetic mixtures in rocket engines. This is just what Blue Origin’s future moon landing craft will consume (the more conservative SpaceX project will burn methane and oxygen).
The production of lunar water in industrial quantities will require large-scale facilities, currently difficult to dream of when the mere construction of a modest permanent base poses so many problems. But someday the Moon becomes a kind of space gas station, those dark craters may be the most valuable terrain in our solar system.
Helium-3: the fuel of the future
On our satellite there is another element with enormous economic potential, helium-3. It is a stable isotope of helium that forms in our star and reaches us carried by the solar wind. On Earth, the magnetic field and atmosphere act as a shield, but on the Moon this protection does not exist and over millions of years helium-3 has been absorbed into the ground. Our entire satellite is a possible deposit. At least, in theory.
When does helium-3 hide the Moon? Some estimates suggest that between one and three million tons, almost all of it accumulated in the outer layers of the regolith, so its extraction would be relatively easy.
On Earth, trace amounts of helium-3 remain trapped in the deep layers of the soil, occasionally escaping in emissions from some gas fields. Most of it is produced artificially in nuclear reactors, by irradiating lithium or as a result of the decay of tritium, an element used in thermonuclear bombs. The progressive dismantling of these arsenals has reduced their availability.
Helium-3 has been described as the fuel of the future in fusion power plants. Its reaction with deuterium releases enormous amounts of energy, producing harmless helium-4 atoms as waste without the emission of dangerous radiation. He Holy Grail of clean energy.
A very rare item
Helium-3 is only available in very small quantities, barely enough for some experiments. Of course, it is very expensive: more than $30,000 per gram. World consumption, limited by restricted supply, is just over half a kilo per year. It is used to build equipment for the nuclear industry, especially neutron detectors. Also to reach very low temperatures, on the order of a few tenths of a degree above absolute zero, mandatory use in quantum instrumentation. And it is increasingly used in biomedical diagnostic imaging applications with magnetic resonance and X-ray spectroscopy equipment.
Analysts estimate that there is a potential demand for helium-3 worth about $400 million, a pie that is not only very attractive, but also shows a clear growing trend. This substance may be scarce on our planet, but there are certainly deposits on the Moon that are easy to exploit, since it is absorbed in the upper layers of the regolith. What may have seemed like science fiction ten years ago is now a real business opportunity.
Several companies are seriously studying this possibility. The latest, Interlune, was recently established in Seattle and has already managed to raise venture capital for more than 13 million dollars. Among its founders, astronaut Harrison Schmitt, the only geologist who has set foot on the Moon and who, therefore, has first-hand knowledge on the subject. He just turned 88 years old.
Interlune managers estimate that helium-3 is the only lunar product whose price justifies its extraction and transportation to Earth. To do this, they are designing an automatic robot that in prototype form will go to our satellite in 2025. In essence, it is a small excavator with an oven to heat the rock samples up to 600 degrees, enough – they hope – to cause the detachment of the rock. occluded gas, which will be collected in small blisters.
The robot, powered by photoelectric cells, will operate during the two weeks of the lunar day and will remain in hibernation at night. And so on, for a couple of years. The technique they have developed—of course, an industrial secret—is only intended to obtain small samples. If successful, commercial exploitation will require larger vehicles, transported by freighters StarShip from SpaceX.
In any case, sending the gas vials to Earth will require return capsules that do not yet exist. And with little load capacity, perhaps limited to a few kilos. At current prices, enough to cover costs and leave an attractive profit.
And where do you plan to start digging? According to Schmitt, the entire Moon offers possibilities, although there are regions more attractive than others. His study of lunar samples and data collected by orbiting satellites has helped him select the most promising place to draw the “X” like on a treasure map. But that map is another of the secrets jealously guarded by the new space miners.
You can follow SUBJECT in Facebook, x and instagramor sign up here to receive our weekly newsletter.
