What will happen if you make a hole through the planet Earth: scientists describe a mega-operation

Traveling through the center of the Earth used to be a popular science fiction story. But as our knowledge of the planet deepened, we realized that along the way we would encounter extreme forces and temperatures that would create conditions far beyond human capabilities.

The Live Science magazine has described what a journey through all the Earth's tectonic layers might look like. Its experts analyzed the experience of existing deep drilling projects and other scientific data.

The diameter of the Earth is 12,756 kilometers, so to drill through the entire planet, a drilling rig of gigantic size and power would be needed. And even with that, it would take decades of work to realize this plan.

According to the U.S. Geological Survey, the first layer to be drilled would be the crust, which is about 100 km thick. As you progress, the pressure in it will increase. Every 3 meters of rock increases this figure by about 1 atmosphere, said Doug Wilson, a research geophysicist at the University of California, Santa Barbara.

The deepest artificial hole in the earth's surface today is the Kola Superdeep Well in Russia. Its depth is 12.2 km. At the bottom of this hole, the pressure is 4000 times higher than at sea level. According to World Atlas, it took almost 20 years to reach this depth, and it is still 80 km higher than the edge of the next layer, the Earth's mantle.

The mantle is a 2800 km thick layer of dark, dense rock. It is home to processes that control the tectonic movements of the plates. The boundary between the mantle and the core is called "Moho" (short for "Mokhorovicic Rift"). The first attempt to reach it took place in the 1950s and 1960s, when scientists tried to drill deep into the sea floor. This attempt was unsuccessful.

One of the obstacles to such plans is that the rock in the borehole tends to crumble, making all efforts in vain. To avoid this, drilling mud must be pumped into the hole. In deepwater and oil drilling, this fluid is a mixture that includes heavy minerals such as barium. The weight of the fluid balances the pressure inside the well with the pressure of the surrounding rock and prevents caving in.

In addition, the drilling fluid is used to continuously clean the drill from sand and gravel and cool it down. However, if you penetrate the deeper layers of the Earth, even this will become impossible. The temperature in the mantle is 1,410 degrees Celsius. According to Wilson, stainless steel will melt under such conditions. Therefore, the drill must be made of an expensive specialized alloy, such as titanium.

At a depth of approximately 2,900 km, the drill will pass through the mantle and reach the Earth's core. According to the California Academy of Sciences, the outer core consists mainly of liquid iron and nickel. Its temperature varies between 4-5 thousand degrees. Drilling through this molten hot iron-nickel alloy will be particularly difficult. Damon Teagle, a professor of geochemistry at the University of Southampton, predicts that drilling this layer will be similar to drilling a liquid. And a substance of this temperature will melt any drill unless a huge amount of cold water is pumped into the hole.

At a depth of 5,000 km, the drill will reach the inner core, where the pressure is so high that, despite the hot temperatures, the nickel and iron core remains solid. Scientists estimate it at about 350 gigapascals, or 350 million times the atmospheric pressure.

All this time, the drill will be attracted to the core by the Earth's gravity. And in the center of the core, conditions similar to weightlessness will arise. That's because the pull of the Earth's mass will be the same in all directions, Wilson said.

When the instrument does pass the core and continues to move to the other side of the planet, the force of gravity will change relative to the position of the drill and begin to pull it back to the core. This means that it will have to work against gravity to reach the Earth's surface from the opposite side. And this will require additional efforts.

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