By a happy coincidence, a body weighing a million tons whizzed tangentially to Earth
On the morning of June 30, 1908, a grandiose explosion took place high in the sky near the Podkamennaya Tunguska River in Western Siberia. This phenomenon went down in the history of natural science as the fall of the Tunguska meteorite. In an interview with journalist Nikolai DROZHKIN, the USSR State Prize laureate, an expert in gas dynamics, heat transfer and heat protection of aircraft, PhD in Physics and Mathematics, Academician of the Russian Academy of Cosmonautics K. E. Tsiolkovsky Ivan MURZINOV.
Ivan Murzinov: "The collision of the Earth with a space body over 10 kilometers in diameter threatens the existence of human civilization." Photo from the author's archive
Ivan Nikitievich, the fall of the Tunguska meteorite is an event more than a century old, but interest in this topic remains and attracts scientists of various specialties. What's the matter?
- It is no coincidence that the problem of the Tunguska meteorite remains relevant. The main reason is that to this day there are no answers to many questions, although there are a myriad of publications. Approximately 30% of researchers believe that it was a meteorite of asteroid origin, the same number say that the Earth met with a comet, and another 40% put forward a variety of hypotheses, including fantastic ones. Unfortunately, there is still no common point of view on this unique phenomenon.
But recently, another factor has emerged. All over the world, the danger threatening humanity was realized associated with the fall of cosmic bodies to the Earth - destructive shock waves, thermal radiation, fires, disturbances of the atmosphere, and with the fall to the Earth - seismic waves, crater formation, tsunamis … The danger is multiplied by the fall of cosmic bodies at the location of nuclear power plants, storage facilities for radioactive waste, hydraulic structures, chemical plants and other facilities. Today it is generally accepted that the collision of the Earth with a space body with a diameter of more than 10 kilometers threatens the existence of human civilization. But bodies with a diameter of several tens of meters can cause great damage. Let me remind you that on February 15, 2013, as a result of the fall of the Chelyabinsk meteorite with a diameter of about 20 meters, more than 1600 people were injured,and the material damage amounted to about a billion rubles.
Therefore, serious attention is paid to the problem of meteorite safety. But in order to successfully resist the meteor hazard, one must have a good understanding of the whole complex of physical processes accompanying the fall of cosmic bodies. That is why it is important to conduct a comprehensive study and study of all factors that are unique in terms of the scale of falls of the Tunguska and Chelyabinsk meteorites.
Promotional video:
Please remind me of the main facts related to the Tunguska phenomenon
- I'll start with the definitions. The following terms are accepted: "meteoroid", "meteor", "fireball", "meteorite". A meteoroid is a small cosmic body that invades the Earth's atmosphere at a speed of 11 to 73 kilometers per second. Meteor - the phenomenon of flash and glow of a meteoroid in the atmosphere. Exceptionally bright meteors are called fireballs. A meteorite is a fallen cosmic body found on Earth.
So, on the morning of June 30, 1908, in a vast area over Eastern Siberia, the flight of a dazzlingly bright fireball and its grandiose explosion was observed high in the sky near the Podkamennaya Tunguska River. In this case, "explosion" is an intense release of kinetic energy of a meteoroid in the atmosphere due to its fragmentation and deceleration of fragments.
As a result of the explosion, the sound of which was heard at a distance of more than 1000 kilometers from the epicenter, over an area of more than 2000 square kilometers, century-old trees were completely felled, and a forest fire was raging in a spot with a diameter of 20 kilometers. An earthquake of magnitude up to 5 points caused by a blast wave was noted over an area of over 3 million square kilometers, and an air blast wave circled the globe.
A number of anomalous phenomena are associated with the flight of the Tunguska meteorite: a local magnetic storm recorded almost 1000 kilometers from the epicenter in Irkutsk; hissing-whistling sounds heard simultaneously with the flight of the meteorite, when the acoustic and shock waves have not yet reached the observer; On the night of June 30 to July 1, 1908, in Central Siberia, the European part of Russia and Western Europe north of the Tashkent – Simferopol – Bordeaux line, and in longitude from the Atlantic to Krasnoyarsk, darkness practically did not come, glowing clouds were observed high in the sky.
Nikolai Vasiliev, Academician of the Russian Academy of Medical Sciences, who has been conducting research on the Tunguska meteorite for decades, noted in his monograph: "… today we can state with full responsibility that the cosmic substance, which could be guaranteed to be identified with the substance of the Tunguska meteorite, has not yet been found" … And this is one of the main mysteries of the Tunguska meteorite, since, according to various literary sources, its mass is about a million tons! And the fact that the Tunguska bolide is called a meteorite is just a tribute to history.
And what searches and studies of the Tunguska meteorite were organized?
- The pioneer, enthusiast and organizer of the meteorite search was Leonid Alekseevich Kulik, a Leningrad meteorologist, author of numerous publications and leader of expeditions to the disaster site in 1927-1939. He first discovered and investigated the epicenter of the explosion, the spot of felling and burns of trees, and drew the attention of the scientific community to this problem.
The first post-war scientific expedition to the place of events was organized in 1958 by the Committee on Meteorites of the Academy of Sciences of the USSR, at the same time in Tomsk the "Comprehensive Amateur Expedition to Study the Tunguska Meteorite" was created, which later became the nucleus of the Commission on Meteorites and Space Dust of the Siberian Branch of the USSR Academy of Sciences.
More than a hundred of the most diverse theories, hypotheses and versions have been put forward. A review of them can be found in the monograph by A. I. Voitsekhovsky and V. A. Romeiko "Tunguska meteorite", 2008. But the Tunguska phenomenon is so multifaceted that none of the hypotheses answers all the questions.
What is the essence of your hypothesis?
- Quite briefly, the starting point of the hypothesis can be stated in one sentence: not all meteoroids entering the Earth's atmosphere fall on its surface. Some of them are flyby, that is, they penetrate the atmosphere and again fly into space. Flyby trajectories are known from observations of some fireballs.
Whether the trajectory of a passing meteoroid or a large meteoroid will fall to Earth is determined mainly by the angle of its entry into the atmosphere at an altitude of 100 kilometers. Research has shown that there is a critical angle of 9 degrees. At large values, all meteoroids will fall to the Earth. At values lower, depending on the ballistic coefficient and the speed of the meteoroid, trajectories both transit and intersecting with the Earth's surface are possible.
After entering the atmosphere, the flight of large meteoroids continues at an almost constant speed up to heights of 30 kilometers, since the resistance of the rarefied upper atmosphere is small. But the air pressure on the frontal surface increases rapidly. So, with a meteoroid entering the atmosphere at a speed of 20 kilometers per second, this pressure reaches 30 atmospheres at an altitude of 35 kilometers and 70 atmospheres at an altitude of 30 km.
Studies of meteoroids show that they have low strength and, when the pressure thresholds are reached, break down into many fragments of different sizes. Small fractions of the meteoroid have a total greater resistance and are intensely inhibited, giving their kinetic energy to the air. And the phenomenon of the release of a large amount of energy in a limited volume in a short period of time is an explosion.
The kinetic energy of the meteoroid is enormous. So, at a meteoroid speed of 20 kilometers per second, each kilogram of its mass has an energy equivalent to 50 kilograms of TNT. According to various literary sources, the mass of the Tunguska meteorite is estimated to be up to 1 million tons, and the explosion power is equivalent to more than 1000 atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki.
What can you say about the testimony of eyewitnesses of the Tunguska phenomenon? Do they allow you to define the parameters of the trajectory?
- As a result of surveys, which were carried out with a long time interval, a huge amount of factual material was collected, often contradictory, but there is no other. Let us cite a very important, in our opinion, excerpt from the newspaper "Siberia" dated July 2, 1908: "… on July 17 in the morning (old style) at the beginning of 9 o'clock we observed some unusual phenomenon of nature. In the village of Nizhne-Karelinsky, the peasants saw in the north-west quite high above the horizon some extremely strong (it was impossible to see) a body glowing with a bluish-white light, moving from top to bottom for 10 minutes. The body was presented in the form of a "pipe", that is, cylindrical … The sky was cloudless, only not high above the horizon on the same side in which the luminous body was observed, there was a noticeably small dark cloud. It was hot and dry. Approaching the Earth (forest),the shiny body seemed to have blurred, but in its place a huge puff of smoke was formed and an extremely strong knock was heard, as if from large falling stones or cannon fire. All buildings were shaking. At the same time, an undefined flame began to burst out of the cloud. All the inhabitants of the village fled into the streets in panic …"
And what information can be extracted from this note?
- The village of Nizhne-Karelinskoe is located at a distance of 465 kilometers from the epicenter of the explosion. This means that due to the curvature of the Earth's surface, residents could only see what was higher than 17 kilometers above the epicenter. They observed the phenomenon of the explosion and its consequences quite high above the horizon. This refutes the explosion height of 7–10 kilometers accepted in the literature.
A huge cloud of smoke indicates that the forest has caught fire from the radiation of the fiery cloud. And the aforementioned small cloud is nothing more than the parts of the Tunguska meteorite left after the explosion. That is, it did not cease to exist, but flew away further!
How do you explain the anomalous phenomena associated with the flight of the meteorite?
- On the night of June 30 to July 1, 1908, in Western Siberia, the European part of Russia and Western Europe, night darkness practically did not come, glowing clouds were observed high in the sky. A similar situation arose after the eruption of the Krakatoa volcano, when a huge amount of ash was thrown into the atmosphere.
Of course, a high-altitude explosion of the Tunguska meteorite could lead to a thorough dusting of the upper atmosphere. Small fractions could be blown away by the wind in 15–20 hours over long distances, but not to Western Europe, too far. No white night after the explosion was observed in northeastern Siberia. This suggests that a northeast wind prevailed at high altitudes in the northern hemisphere.
Now let's look at the hypothetical trajectory of the meteorite (or its fragments) behind the epicenter of the explosion. The meteorite reached the Atlantic in a matter of minutes, leaving behind a plume of dust and creating conditions for a white night in the vast territory of Eurasia.
Concerning the white night, the Danish astronomer Kool already on July 4, 1908, in hot pursuit, wrote: "… it would be desirable to know if a very large meteorite has not appeared recently in Denmark or anywhere else."
Let us dwell on two more Tunguska anomalies that have not yet received an unambiguous explanation.
A few minutes after the passage of the meteorite, magnetometers in Irkutsk (about 900 kilometers from the epicenter) recorded a local magnetic storm that lasted for several hours. Magnetic storms occur when there is a sharp change in the flow of charged particles to the Earth from the Sun due to its rotation and non-stationary nuclear processes in it.
A high-temperature trail with an extremely high density of charged particles is formed behind the Tunguska meteorite flying in the atmosphere. Calculations show that the flux of these particles through the wake cross-sections even exceeds the flux of particles from the Sun through the Earth's cross-section. Therefore, it is not surprising that the Tunguska meteorite caused a local magnetic storm. By the way, local magnetic storms are recorded when rockets are launched from the Baikonur test site at a distance of about 800 kilometers. This is due to the emission of a large amount of charged particles into the atmosphere by the rocket propulsion system.
Many eyewitnesses noted that the Tunguska meteorite was electrophonic …
- This is the name given to bright fireballs that emit hissing-whistling sounds, heard simultaneously with their flight, when acoustic and shock waves could not reach the observer yet. Such phenomena have been known for a long time, but there is still no satisfactory explanation for this phenomenon. One of the first hypotheses of the physics of electrophone fireballs was the hypothesis of the astronomer I. S. Astapovich, according to which the sound was generated by the outflow of static electricity from terrestrial objects, induced by the passage of a meteoroid. Other researchers associated this phenomenon with electromagnetic disturbances without a clear explanation of their connection with sound waves.
About a third of all fireballs, the brightest and most long-lived, are electrophonic. These fireballs emit significant thermal energy, mainly in the infrared wavelength range, which is absorbed by the Earth's surface. Different areas of the surface - forest, water, field - have different physical characteristics and are heated to different temperatures, transferring heat to the surface air layer, which creates certain pressure drops. There is a wind that creates hissing and hissing sounds.
Based on the above and the known facts, what is the picture of the Tunguska phenomenon for you?
- On the morning of June 30, 1908, a giant stone meteoroid of asteroid origin entered the Earth's atmosphere at a speed of about 20 kilometers per second along a very flat trajectory. The angle of its entry into the atmosphere at an altitude of 100 kilometers was in the range of 7-9 degrees. Having flown about 1000 kilometers, the meteoroid was destroyed by high pressure and exploded at an altitude of 30-40 kilometers. The forest was set on fire by radiation from the explosion core. Shock waves carried out a continuous felling of forests in a spot about 60 kilometers in diameter and caused an earthquake of magnitude up to 5 points.
Small fragments of the Tunguska meteorite with a characteristic size of up to 0.2 meters burned (evaporated) at the epicenter of the explosion. Larger fragments, given the height of the explosion and the small angle of inclination of the trajectory, flew into the taiga for hundreds and thousands of kilometers in accordance with their ballistic coefficients. The largest fragments of the meteorite could fall into the Atlantic Ocean and even go back into space.
The clogging of the upper atmosphere with explosion products and debris moving along the trajectory led to optical anomalies over the vast territory of Eurasia. A meteorite trail with high levels of charged particles triggered a localized magnetic storm. Radiation radiation and uneven heating of the surface layer of the air made this car electrophonic.