The Soviet Union’s dream of “digging through” the earth stopped at 12,262 meters. How far can we go?

"Going to heaven and into earth" has been the dream of mankind since ancient times. Since mankind has realized what the real heaven is and what the real earth is, the desire to achieve the dream has become stronger.

What is heaven? Heaven is the deep space of the universe, and what is earth? The earth is the earth under our feet. It is difficult to go to heaven, because to go to heaven, you must get rid of the gravitational pull of the earth and reach the first cosmic speed of at least 7.9 kilometers per second, and humans have done it. Not only have humans gotten rid of the gravity of the earth and entered low-Earth orbit, they have even been able to completely get rid of the influence of the earth's gravity and land on and explore the moon, which is 380,000 kilometers away. And since humans launched the first artificial earth satellite, it has only taken more than 60 years to achieve today's achievements. Humans have successfully gone to heaven, so what about going underground? Speaking of going underground, we have to mention the "Kola Superdeep Borehole" dug by the Soviet Union.

Why did the Soviet Union dig a super-deep borehole? What was the significance of this project?

At that time, it was the Cold War between the United States and the Soviet Union. The Cold War involved all aspects from military to technology. "Going to the sky and into the earth" was naturally a competition project. In this competition, the United States was the first to complete the manned lunar landing. Since it could not compete with the United States in "going to the sky", it could only work hard on "going into the earth". So a project called "Kola Superdeep Borehole" officially started on May 24, 1970. Of course, the Soviet Union wanted to dig through the earth not just to be angry with the United States. The Kola Peninsula where the project was located was located in the northwest of the Soviet Union. The upper strata in this area were ancient. Through excavation and research, information about the original geological structure of the earth could be obtained. If it could really dig through the earth as desired, then its achievement would be far better than the manned lunar landing.

The problem is that "going underground" is much more difficult than "going to the sky".

At the beginning, the project progressed smoothly. It took only 13 years, that is, in 1983, the Kola Superdeep Borehole reached a depth of 12,000 meters. There is no doubt that the Kola Superdeep Borehole has become the deepest human construction on Earth. However, the deeper the drilling, the higher the difficulty. In the next 6 years, the drilling depth only advanced by more than 200 meters. After that, the speed of advancement was even slower. Finally, the Kola Superdeep Borehole project was stopped in 1994 and finally stopped at 12,262 meters. In the next decade, scientists conducted a thorough study of the depths that the Kola Superdeep Borehole had achieved, and finally sealed the borehole with a metal cap in 2008.

Why did the Soviet Union's dream of digging through the earth fail to continue? Will we be able to realize this great dream in the future? I'm afraid it will be difficult.

The Kola Superdeep Borehole sounds like just a project of continuously drilling downwards, but in fact the technical difficulty of this project is very high. First of all, the drilling process will encounter hard rocks, so the drill bit will wear very quickly. With the increase of depth, the ambient temperature is also gradually increasing. According to records, at 12,000 meters, the temperature has reached 180 degrees Celsius, which undoubtedly increases the wear rate of the drill bit. Sometimes a new drill bit has just been installed, and it has not been drilled a few times before it needs to be replaced. Therefore, the cost of consumables, equipment, and labor together is a huge amount of money, which is a test of a country's economic strength.

Of course, it doesn’t mean that just having money will solve all the problems. Some technical problems are difficult to solve even today.

A depth of 12,000 meters requires an extra-long drill pipe, and this drill pipe must also have considerable strength. Even with this super-strong drill pipe, a super-strong motor is still needed to drive it to rotate. 12,000 meters can be solved, so what about 15,000 meters? What about 20,000 meters? Moreover, drilling alone is not enough. We also need equipment that can be free from various interferences to monitor and record the situation in the borehole. These problems are not only in the former Soviet era, but even today, there is almost no way to solve them. The former Soviet Union failed to drill through the earth, and there is no way to drill through the earth now, so what about the future? No one can give a definite answer, but it is obviously difficult.

The earth is composed of multiple different structures from the inside out, namely the core, mantle and crust. Among them, the crust is the thinnest, with an average thickness of about 17 kilometers. This means that so far humans have not even dug through the crust, let alone digging through the earth.

Of course, the thickness of the earth's crust is not uniform. Some places are very thin, such as the 10,000-meter deep sea, where the crust may be only a few kilometers thick. However, the technical difficulty of drilling under the huge pressure of 10,000 meters deep sea is beyond the reach of today's technology, so we can only look forward to the future. So since humans have not even drilled through the crust, how do they know the structure of the earth? It was discovered by the former Yugoslav seismologist Mohorovic when studying seismic waves. Because the propagation mode of seismic waves in different underground structures is different, due to Mohorovic's contribution, the interface between the crust and the mantle is called the Moho surface.

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