What is the price of the Moon?
Russia's Victory Day Parade was a bit more exciting for the Russians in 2014 because Crimea became a part of the Russian victory. However, on the same day, Russia also published some details about its space program:
China has promised to send its first troops to the Moon in 2025. ;-)
Unless the modern civilization destroys itself in some way – e.g. by allowing the extremists known as "environmentalists" to influence our lives – the Moon will eventually become a "possible destination". But will the human activity on the Moon ever become significant for our planet? Will the Moon ever become the source of a non-negligible portion of the world GDP?
What is the price of the Moon?
With its radius of 1,740 km, to be compared with Earth's 6,380 km, the total area of the lunar surface is 38 million squared kilometers. That's pretty close to the total area of the Americas. One-half of the surface (imagine another South America) lies on the permanently invisible side (from the Earth), the other half (imagine another North America) sits on the permanently visible side (from the Earth). Note that it's not true that one-half of the lunar surface is permanently "bright" because the brightness depends on the relative orientation with respect to the Sun and this orientation is changing with time.
If this were a territory that is as pleasant and productive as the same area on the Earth, it would be a great place to live, indeed. However, the Moon doesn't have a thick enough atmosphere and it seems unlikely that we will be able to create one. So the life and the "ordinary" human activity on the Moon is likely to be much less pleasant and valuable than the life on the Earth. It's just very hard and risky to fly to the Moon and the benefits are limited.
In other words, if the Moon is going to be practically important for the mankind, it will be due to some of its advantages in which it totally beats the Earth.
Some people have suggested that the Moon could be covered by solar panels to produce the energy for us. It would have to be transferred to the Earth in some way – by light from lasers? – but let's assume that this problem is solved. Will it ever be economically feasible to build photovoltaic power plants on the Moon? Well, I doubt it because the amount of energy per squared meter is not significantly larger than it is on the Earth. And the extra expenses are probably huge enough so that the solar panels on the Moon are likely to be less economically acceptable than the same panels on the Earth.
We're coming to another potential advantage of the Moon, the natural resources.
Ironically enough, the lunar soil offers us a larger concentration of elements that we call "rare earths" than the Earth. Maybe "rare earth" really means "soils rare on Earth, more abundant on the Moon". ;-) Will we ever be mining these things on the Moon and send them to the Earth by spaceships? It seems more likely to me than squared kilometers of solar panels on the Moon but I still find it unlikely because the increased concentration of the rare earths on the Moon isn't that high, either. The price of getting a kilogram of rare earths to the lunar orbit etc. still seems to exceed the price of the kilogram on the Earth today and this counting is unlikely to change dramatically in coming decades.
But there's one element/isotope that is much more abundant on the Moon, namely helium-3. It's believed that helium-3, a stable yet lighter isotope of the inert helium gas (not to be confused with hydrogen-3, the tritium), is significantly more abundant in the upper layer of the lunar regolith. It's believed that the solar wind has been bringing helium-3 over there for billions of years.
Helium-3 is extremely rare on Earth. Helium itself is rare and only 1.37 parts per million of the helium on Earth is helium-3; the rest is helium-4. OK, imagine that we can get lots of helium-3 from the Moon. What is it good for? It may be used for lung imaging, cooling, and other things. But thermonuclear reactions make helium-3 most useful.
Unlike tritium (hydrogen-3: half-life 12 years) and like deuterium (hydrogen-2), helium-3 is stable. And it may be fused with itself or with various isotopes of hydrogen to produce some other isotopes of the hydrogen and helium and/or protons or neutrons and 10 MeV of energy per reaction in average. There is no radioactive waste whatsoever.
We can't really build thermonuclear power plants burning helium-3 yet; the estimate has always been that this technology will arrive 50 years in the future. However, people are not even trying to build specific reactors burning helium-3 because the amount of available helium-3 on the Earth is so small that even if you built a reactor, you would suffer from a shortage of the fuel if you wanted to replace the existing sources of energy.
If we had enough helium-3, it could stimulate the research of the thermonuclear reactors. And the reactors burning helium-3 could turn out to be simpler to construct than those that are being built today.
At any rate, it seems likely to me that it would only become economically sensible to mine for helium-3 on the Moon if we could use it as a fuel. For the other applications, the available helium-3 seems pretty much enough. If the thermonuclear reactors are ever built, the price of the Moon as a potential source of helium-3 may skyrocket. To calculate the actual price of the Moon, you need to know lots of things. For example: Will there also be equally acceptable reactors that burn the isotopes available on Earth? Only in their absence, the helium-3 and the Moon is really important.
What is the actual amount of helium-3 that may be obtained from the Moon? There could be enough fuel for 10,000 years of the mankind's needs. But is that really accurate? Will we be able to construct the reactors?
There are many questions but assuming that none of the relevant probabilities are "vastly smaller" than 100 percent, the Moon may still cost trillions of dollars, to say the least. There are no international laws regulating the annexation of territories on the Moon and even if there were such laws, no one would be able to enforce them. So the ambitious people and nations that arrive might benefit a lot. It is a very long-term investment but spending billions of dollars annually for the future colonization of the Moon might be a good idea for every power that is thinking about its future around the year 2050 or 2100.