It is shown that self-sinking of a spherical probe in the form of a capsule filled with radionuclides, whose decay heats and melts the rock in its path, deep into the Earth is possible. Information on the formation, structure, and shifts deep in the Earth can be obtained by recording and analyzing acoustic signals from the recrystallization of the rock by the probe. It is shown that such capsules can be placed at a prescribed depth. Self-sinking probes can be used to study the formation of deep layers in the Earth, prospect for minerals, and study underground motions in seismically active regions.The great interest in the interior structure of the Earth is not diminishing but many details of the Earth's structure are still undetermined [1][2][3][4][5][6][7]. Thus, the sources which maintain the Earth's heat balance, the role of 40 K in this balance [2], and the nature of the high fluidity of the magma at a definite depth [4, 5] remain unclear. Only near-surface layers of the Earth are accessible for direct observation, as a result of which many details of the Earth's structure remain unknown.Modern technology permits drilling superdeep wells on continents (up to 10-15 km deep). The deepest exploratory well Bertha Rogers (USA) is 9583 m deep, and the scientific well KTW-Oberpfaltz (Bavaria) has reached a depth of 9101 m. According to the international program of deep-water drilling, the deepest well has been drilled in the Pacific Ocean south of Costa Rica (2105 m below the ocean bottom). Drilling of the Kola superdeep scientific well began in 1970. Its projected depth is 15 km. Although drilling stopped at a depth of 12261 m in 1991, it still remains the deepest well in the world [6,7]. Drilling superdeep wells takes years and is very expensive.Reaching a large depth poses insurmountable barriers for drilling mainly because of increasing pressure and temperature. At great depths, the difference between the hydrostatic pressure of a column of the drilling solution and the lithostatic pressure due to the mass of the rocks becomes substantial, which causes the walls of the well to collapse. The high temperature in the deep interior of the Earth remains one of the chief factors limiting the drilling depth. The thermal stability of the drilling equipment does not exceed 573 K, so that modern technical means do not make it possible to drill wells for a long time to a depth where the temperature is above this value. At the same time, as the depth increases, the rock temperature increases, for example, at the bottom of the Salton Sea well (USA) 3220 m the temperature reached 628 K, so that drilling becomes impossible at very large depths. There are also serious technical difficulties with spontaneous curving of deep wells during drilling. For example, the Kola well at a depth of about 12 km deviated from the vertical by 840 m, and the KTB-Oberpfaltz well at a depth of 9101 m deviated by 300 m [6,7].Various possibilities for reaching a great depth in the Earth are being examined theoretically. An example is explosive pene...
