Although people long ago began to wonder whether the "canals" on Mars were the creation of cosmic engineers, for some odd reason it has not occurred to look with the same eyes upon the peculiarities of the lunar landscape much closer at hand.
And all the arguments about the possibilities of intelligent life existing on other celestial bodies have been confined to the idea that other civilizations must necessarily live on the surface of a planet, and that the interior as a habitat is out of the question.
Abandoning the traditional paths of "common sense", we have plunged into what may at first sight seem to be unbridled and irresponsible fantasy.
But the more minutely we go into all the information gathered by man about the Moon, the more we are convinced that there is not a single fact to rule out our supposition.
Not only that, but many things so far considered to be lunar enigmas are explainable in the light of this new hypothesis.
AN ARTIFICIAL SPUTNIK OF THE EARTH?
The origin of the Moon is one of the most complicated problems of cosmogony. So far there have been basically three hypotheses under discussion.
HYPOTHESIS I: The Moon was once a part of the Earth and broke away from it. This has now been refuted by the evidence.
HYPOTHESIS II: The Moon was formed independently from the same cloud of dust and gas as the Earth, and immediately became the Earth's natural satellite.
But then why is there such a big difference between the specific gravity of the Moon (3.33 grams per cubic centimeter) and that of the Earth (5.5 gr.)?
Furthermore, according to the latest information (analysis of samples brought back by the U.S. Apollo astronauts) lunar rock is not of the same composition as the Earth's.
HYPOTHESIS III: The Moon came into being separately, and, moreover, far from the Earth (perhaps even outside the Solar system).
This would mean that the moon would not have to be fashioned from the same "clay" as our own planet.
Sailing through the Universe, the Moon came into Earth's proximity, and by a complex interplay of forces of gravity was brought within a geocentric orbit, very close to circular.
But a catch of this kind is virtually impossible.
In fact, scientists studying the origin of the Universe today have no acceptable theory to explain how the Earth-Moon system came into being.
OUR HYPOTHESIS: The Moon is an artificial Earth satellite put into orbit around the Earth by some intelligent beings unknown to ourselves.
We refuse to engage in speculation about who exactly staged this unique experiment, which only a highly developed civilization was capable of.
A NOAH'S ARK?
If you are going to launch an artificial sputnik, then it is advisable to make it hollow.
At the same time it would be naive to imagine that anyone capable of such a tremendous space project would be satisfied simply with some kind of giant empty trunk hurled into a near-Earth trajectory.
It is more likely that what we have here is a very ancient spaceship, the interior of which was filled with fuel for the engines, materials and appliances for repair work, navigation, instruments, observation equipment and all manner of machinery...
In other words, everything necessary to enable this "caravelle of the Universe" to serve as a kind of Noah's Ark of intelligence, perhaps even as the home of a whole civilization envisaging a prolonged (thousands of millions of years) existence and long wanderings through space (thousands of millions of miles).
Naturally, the hull of such a spaceship must be super-tough in order to stand up to the blows of meteorites and sharp fluctuations between extreme heat and extreme cold.
Probably the shell is a double-layered affair - the basis a dense armoring of about 20 miles in thickness, and outside it some kind of more loosely packed covering (a thinner layer - averaging about three miles).
In certain areas where the lunar "seas" and "craters" are, the upper layer is quite thin, in some cases, non-existent.
Since the Moon's diameter is 2,162 miles, then looked at from our point of view it is a thin - walled sphere. And, understandably, not an empty one.
There could be all kinds of materials and equipment on its inner surface. But the greatest proportion of the lunar mass is concentrated in the central part of the sphere, in its core, which has a diameter of 2,062 miles.
Thus the distance between the kernel and the shell of this nut is in the region of 30 miles.
This space was doubtless filled with gases required for breathing, and for technological and other purposes.
With such an internal structure the Moon could have an average specific gravity if 3.3 grams per cubic centimeter, which differs considerably from that of Earth (5.5 grams per cubic centimeter).
A BATTLESHIP THEY COULDN'T TORPEDO?
The most numerous and interesting of the formations on the lunar surface are the craters.
In diameter they vary considerably. Some are less that a yard across, while others are more than 120 miles (the biggest has a diameter of 148 miles). How does the Moon come to be so pockmarked?
There are two hypothesis - volcanic and meteoric. Most scientists vote for the latter.
Kirill Stanyukovich, a Soviet physicist, has written a whole series of works since 1937 in which he expounds the idea that the craters are the result of bombardment of the Moon for millions of years.
And he really means bombardment, for even the smallest celestial body, when it is involved in one of those fastest head-on collisions so common in the cosmos behaves itself like a warhead charged with dynamite, or even an atomic warhead at times.
Instant combustion takes place on impact, turning it into a dense cloud of incandescent gas, into plasma, and there is a very definite explosion.
According to Professor Stanyukovich, a "missile" of a sizable character (say 6 miles in diameter) must, on collision with the Moon, penetrate to a depth equal to 4 or 5 times its own diameter (24-30 miles).
The surprising thing is that however big the meteorites may have been which have fallen on the Moon (some have been more than 60 miles in diameter), and however fast they must have been travelling (in some cases the combined speed was as much as 38 miles per second), the craters they have left behind are for some odd reason all about the same depth, 1.2-2 miles, although they vary tremendously in diameter.
Take that 148-mile diameter crater. In area it outdoes Hiroshima hundreds of times over.
What a powerful explosion it must have been to send millions of tons of lunar rock fountaining over tens of miles!
On the face of it, one would expect to find a very deep crater here, but nothing of the sort: there is three miles at the most between top and bottom levels, and one third of that is accounted for by the wall of rock thrown up around the crater like a toothed crown.
For such a big hole, it is too shallow. Furthermore, the bottom of the crater is convex, following the curve of the lunar surface.
If you were to stand in the middle of the crater you would not even be able to see the soaring edge -- it would be beyond the horizon. A hollow that is more like a hill is a rather strange affair, perhaps.
Not really, if one assumes that when the meteorite strikes the outer covering of the moon, this plays the role of a buffer and the foreign body finds itself up against an impenetrable spherical barrier.
Only slightly denting the 20-mile layer of armour plating, the explosion flings bits of its "coating" far and wide.
Bearing in mind that the Moon's defense coating is, according to our calculations, 2.5 miles thick, one sees that this is approximately the maximum depth of the craters.
A SPACESHIP COME TO GRIEF?
Now let us consider the chemical peculiarities of the lunar rock.
Upon analysis, American scientists have found chromium, titanium and zirconium in it. These are all metals with refractory, mechanically strong and anti-corrosive properties.
A combination of them all would have enviable resistance to heat and the ability to stand up to means of aggression, and could be used on Earth for linings for electrical furnaces.
If a material had to be devised to protect a giant artificial satellite from the unfavorable effects of temperature, from cosmic radiation and meteorite bombardment, the experts would probably have hit on precisely these metals.
In that case it is not clear why lunar rock is such an extraordinarily poor heat conductor - a factor which so amazed the astronauts?
Wasn't that what the designers of the super-sputnik of the Earth were after?
From the engineers point of view, this spaceship of ages long past which we call the Moon is superbly constructed. There may be a good reason for its extreme longevity.
It is even possible that it predates our own planet.
At any rate, some pieces of lunar rock have proved older than the oldest on Earth, although it is true, this applies to the age of the materials and not of the structure for which they were used.
And from the number of craters on its surface, the Moon itself is no chicken.
It is, of course, difficult to say when it began to shine in the sky above the Earth, but on the basis of some preliminary estimates one might hazard a guess that it was around two thousand million years ago.
We do not, of course, imagine that the moon is still inhabited, and probably many of its automatic devices have stopped working, too.
The stabilizers have ceased functioning and the poles have shifted.
Even though the moon keeps that same side turned towards us, for some time it has been unsteady on its own axis, on occasion showing us part of its reverse side which were once invisible to observers on the Earth - for example, the Selenites themselves if they made expeditions here.
Time has taken its toll. Both body and rigging have disintegrated to some extent; some seams on the inner shell evidently diverged.
We assume that the long (up to 940 miles) chains of small craters formerly ascribed to volcanic activity were brought about by eruptions of gas through cracks appearing in the armour plating as a result of accidents.
No doubt one of the most splendid features of the lunarscape - a straight "wall" nearly 500 yards high and over 60 miles long - formed as a result of one of the armor plates bending under the impact of celestial torpedoes and raising one of its straight, even edges.
The Moon's population presumably took the necessary steps to remedy the effects of meteorite bombardment, for example, patching up rents in the outer shield covering the inner shell.
For such purposes a substance from the lunar core was probably used, a kind a cement being made from it.
After processing this would be piped to the surface sites where it was required.
Not long ago astronomers discovered variations in the gravitational fields near the large "seas".
We believe the reason to be this: the Moon's dry seas are in fact areas from which the protective coating was torn from the armor cladding.
To make good the damage to these vast tracts, the installation producing the repair substance would have had to be brought immediately beneath the site so that it could flood the area with its "cement".
The resulting flat stretches are what look like seas to the terrestrial observer.
The stocks of materials and machinery for doing this are no doubt still where they were, and are sufficiently massive to give rise to these gravitational anomalies.
What is the Moon today? Is it a colossal necropolis, a "city of the dead," where some form of life became extinct?
Is it a kind cosmic Flying Dutchman? A craft abandoned by its crew and controlled automatically?
We do not know and we shall not try to guess.
WAITING FOR THE EVIDENCE
We have put forward in this article only a few of the reasons - unfortunately the evidence is so far only circumstantial - for our hypothesis, which at first glance may appear to be crazy.
A similar "crazy" idea was put forward in 1959 by Professor Iosif Shklovsky, an eminent scientist, in relation to the "moons" circling around Mars.
After carefully weighing up the evidence he concludes that they are both hollow and therefore artificial satellites.
We feel that the questions we have raised in connection with our Moon provide sufficient food for serious thought on the matter; the result may be the illumination of our many lunar riddles.
Now, of course, we have to wait for direct evidence to support our idea. Or refute it...