NASA’s computer models show that the Tunguska meteorite was quite large, and an analysis of eyewitness accounts indicates that there were three dozen people in its fall zone. This is written by scientists from the American Space Agency and their Russian colleagues in the journal Icarus.
“During the entire existence of mankind, we were able to trace an extremely small number of large meteorites, and therefore we do not know how asteroids break up in the atmosphere and what damage they can cause. The fall of the Chelyabinsk meteorite and the new calculation methods helped to deepen our understanding of their behavior” – tells Lorien Wheeler (Lorien Wheeler) from the NASA Ames Research Center (USA).
At the end of June, the Tunguska meteorite celebrates a kind of anniversary. Exactly 111 years ago, it fell in a deserted corner of Siberia, destroying a huge stretch of forest comparable in size to Hong Kong. This remains the largest natural catastrophe caused by a meteorite, which was traced in detail.
The fall of the Chelyabinsk meteorite in February 2013 made both the public and scientists recall the Tunguska meteorite and begin to re-examine the consequences of its fall. These data, as suggested by planetologists, are crucial to assess how often such celestial bodies fall on our planet.
Since serious observations of the Tunguska meteorite were not made, astronomers could estimate its size and localize the alleged place of its origin only approximately. But, as Wheeler notes, modern computer technology can solve this problem.
Based on eyewitness accounts, the extent of damage and the absence of a crater, NASA scientists built a computer model of the Tunguska event and calculated 50 million of its scenarios. These calculations were based on one of the latest mathematical models, realistically describing how meteorites disintegrate and burn in the atmosphere.
As a result, astronomers were able to calculate the approximate power of the explosion, the speed of the asteroid, its size and mass, as well as density. As it turned out, the Tunguska meteorite was somewhat larger than previously thought — its probable diameter was about 75 meters, and the strength of the explosion was close to the most powerful Soviet and American thermonuclear bombs — more than 20 megatons.
Most likely, the meteorite fell apart and exploded at an altitude of about 12-17 kilometers, so the diameter of the affected area was an impressive 5-12 kilometers. Such events occur infrequently, however, as Wheeler and her colleagues believe, the rarity is more than offset by destructive potential.
According to the scientists from the American Institute SETI and their Russian colleagues from the Institute of Astronomy and the Institute of Dynamics of the Geosphere of the Russian Academy of Sciences, in the case of the Tunguska meteorite, humanity was lucky – it fell in a relatively deserted region of the Russian Empire.
At the same time, we managed to count the number of people who could have been victims of the asteroid’s fall. To do this, the researchers analyzed all available records of the words of eyewitnesses, including the stories of local Evenk reindeer herders recorded by Soviet researchers.
In total, over seven hundred stories have been studied, in which the names of almost two thousand inhabitants of this region of Eastern Siberia are mentioned. As scientists assume, in the affected area at that time there were only three dozen people.
According to eyewitnesses, many people lost consciousness and were seriously injured, at least three died either during the explosion of the asteroid, or a few days after it. The cause of death was either the blast wave itself, or burns caused by the fall of a celestial body, and because of forest fires.
As American and Russian researchers hope, these calculations and observations will help to better understand how small asteroids threaten civilization as a whole and individual cities, as well as how to defend against them.