A team of Russian scientists has proposed a new explanation for why fragments of the Tunguska meteorite were not expected to fall. According to their calculations, the destruction in that area is not associated with the fall of a space object to the Earth, but with shock waves that arose during the passage of an iron asteroid through the Earth's atmosphere. The researchers' article was published in the Monthly Notices of the Royal Astronomical Society.
Asteroids and comets attract the attention of scientists and ordinary people, as they pose a particular danger to the inhabitants of the Earth. On June 30, 1908, an event was recorded over Siberia in the Podkamennaya Tunguska area, the reasons for which are still being discussed in the scientific community. At the moment, it is believed that the Tunguska meteorite is a comet. It was she, according to the most likely version, who was responsible for the explosion in the area of the Podkamennaya Tunguska River. This point of view is supported by the absence of meteorite debris and the structure of the felling.
Now Russian researchers from the Federal Research Center "Krasnoyarsk Scientific Center of the SB RAS", Siberian Federal University and the Moscow Institute of Physics and Technology have calculated the trajectory and mass of the space object, external forces acting on it and changes in its initial velocity. Based on the analysis of these data and the performed modeling, they presented a new explanation of the Tunguska phenomenon. The authors showed that the damage caused by the alleged cosmic body could be caused by a shock wave. An explosive impact could occur when a cosmic body passed through the Earth's atmosphere, provided that it consisted not of ice, like cometary nuclei, but of iron.
“We have calculated the characteristics of the trajectory of space objects with a diameter of 200 to 50 meters, which are composed of iron, ice or rocks such as quartz and lunar soil. This model showed that the Tunguska body could not consist of stone or ice, since, due to the low strength of these materials, they quickly collapse in the atmosphere and can evaporate before reaching the ground,”says the project manager, leading researcher at the Institute of Physics them L. V. Kirensky FRC KSC SB RAS Sergey Karpov.
The new model also takes into account the change in the trajectory of the space body depending on the aerodynamic drag, the angle and speed of entry into the atmosphere, the properties of the body material and its passage through various layers of the atmosphere. The simulation results showed that the Tunguska phenomenon was most likely due to the passage of an iron asteroid with the most probable size from 100 to 200 meters. This asteroid passed through the planet's atmosphere at an altitude of at least 10-15 kilometers at a speed of about 20 kilometers per second. After that, the body continued to move in the circumsolar orbit, having lost about half of its initial mass, but retaining its integrity.
Such an object could well create a shock wave that could cause felling in an area of one and a half thousand square kilometers. The main contribution was made by the spherical component of this shock wave, which is characteristic of an explosion. Calculations have shown that its occurrence is associated with a sharp increase in the rate of evaporation of the body when approaching the epicenter in the upper layers of the troposphere up to 500 thousand tons per second due to the strong heating of its surface. Such a large mass can instantly expand in the form of a high-temperature plasma, creating an explosion effect.
Another mystery of the Tunguska phenomenon is the cause of the fires that engulfed the epicenter area with an area of more than 160 square kilometers. The explanation for this phenomenon is associated with the action of high intensity light radiation, which can create an asteroid when entering the atmosphere. Moreover, the temperature of its radiating surface should be more than 10,000 degrees at the minimum flight altitude. Scientists have found that it is in such conditions on the surface of the Earth that the ignition temperature of combustible materials such as wood is reached. For this, 1–1.5 seconds of exposure is enough.
Author: Nikita Shevtsev
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