Someone said that the human beings knows more about certain distant galaxies than it does about the ground that lies beneath its very feet. In fact, while it took the popular Voyager 1 satellite 26 years to exit our Solar System, relaying measurements to Earth from 16.5 billion km away, it took about the same amount of time for humanity to penetrate a just 12 km into the Earth’s surface!
Since the dawn of literature, the mystery that hides beneath the earth’s crust has been examined by illustrious poets, writers and scholars. For example, Dante Alighieri accesses the subsoil with Virgil in the Divine Comedy and Jules Verne in “Journey to the Center of the Earth” imagines the scenery with interesting and vivid descriptions.
Going beyond the margins, the obstacles that the nature imposes on us, has always been a desire of man, and of course of scholars and scientists.
For the latters, discovering what the earth’s coating hides is a ever-growing challenge, since a very long time. Numerous advances have been achieved, also and above all thanks to the invention of machinery suitable for drilling the hard rocks below the earth’s crust.
Instead of let the imagination wander, at the end of the 1950s, scientists faced the problem buolding huge drills, with the aim of discovering the secrets of the subsoil.
So, while the U.S. and U.S.S.R. vied for space exploration supremacy during the Space Race, a different, less-publicized challenge took place between the two nation’s greatest drillers. In the late 1950s and early 1960s Americans and Soviets began planning separate efforts to drill as deep as possible into the Earth’s crust, the rocky shell that comprises the outer 30-50 km of the 6730 km distance to our planet’s core.
In the United States the project began in 1957, it was named “Project Mohole” and settled off the Pacific coast of Mexico. Although armed with the best intentions, the Americans were forced to interrupt their activities in 1966 due to lack of funds.
Below, one of the six submerged buoys used for the dynamic positioning of the Project Moonhole. When they were about 60 meters down, they were placed in a circle, with the drill that was at work in its center:
The Soviets, thanks to the planning of the Interdepartmental Scientific Council for the Study of the Earth’s Interior and Superdeep Drilling, had greater success.
So, almost simultaneously, Soviets rivals began their drilling operations, located along the Kola Peninsula on the Baltic coast. The project was called “Kola Superdeep Borehole” (Kolskaya sverkhglubokaya skvazhina, in Russian), and began on May 24th 1970.
From that year, until 1994, the Russians managed to penetrate as much as a third of the earth crust, creating an Earth-shattering record at the time: the deepest hole in the world.
In 1970, the year the work began, the goal was to reach about 14 kilometers deep underground. To obtain this, various wells were drilled which, through a branching, would have led to the main one.
The deepest branch of these is called SG-3 and by 1989 it had reached a depth of 12 kilometers!
The Russians set themselves the goal, by 1990, to reach 13 kilometers, and finally the 14 kilometers by 1993.
However and unexpectedly, the temperatures reached at that depth made it impossible to continue the work, and stopped everything. Scientists had estimated that at a depth of 12 kilometers, a temperature of around 100 degrees Celsius could be expected: there were instead 180.
Taking note of the data, it was decreed impossible to continue drilling more deeply, since it would have reached the impractical temperature of 298 degrees centigrade.
Also unexpected was a decrease in rock density after the first 4,5 km. Beyond this point the rock had greater porosity and permeability which, paired with the high temperatures, caused the rock to behave more like a plastic than a solid and made drilling near impossible.
Drilling was carried out using the Uralmaš 4E drilling rig and later the 15000 series Uralmaš.
The final depth reached was 12,261 meters.
Therefore, drilling operations stopped in the late nineties, and the project was permanently closed in 2006. The structures were abandoned in 2008, and are still present on the site, visited by the curious.
Although it was an unfinished work, the Kola Superdeep Borehole gave the scientific world great satisfactions: needless to say, the project produced enormous amounts of geological data, most of which elucidated how little we know about our planet. One of the most interesting is undoubtedly the discovery of fossil plankton clusters, found 6 kilometers below the earth’s surface. Despite the high temperatures, the fossils were incredibly intact, therefore suitable for scientific study.
However the ambitious project highlighted how human beings are powerless against nature, and how big it is compared to us.
For its ambitious purposes and its contributions to geology and biology, the Kola Superdeep Borehole remains one of the most important relics of Soviet-era science.
Author’s note: The Kola Superdeep Borehole is located 10 kilometers north of the town of Zapolyarny, in the Pechengsky District of Murmansk Oblast, Russia.
Below, the site in 2012, completely abandoned:
Photos from web.