Until now, not a single confirmed case of human killing by a meteorite is known. And at the same time, even a small celestial body, which, unfortunately, has invaded the Earth's atmosphere, has a colossal destructive potential comparable to nuclear weapons. Sometimes, as recent events have shown, guests from heaven can catch us by surprise.
The shockwave generated by the destruction of a meteorite can bring much more trouble than the fall of a large debris. The photo shows a hole in the ice of Lake Chebarkul, presumably punctured by a piece of the Chelyabinsk meteorite.
Recently, a meteorite, passing in the sky over Khabarovsk, literally turned the top of the mountain into rubble. And the fireball that flew over Chelyabinsk and made so much noise in the literal and figurative sense amazed everyone with its incredible glow and shock wave that crumbled glass, carried out the gate and tore off the facing panels from the walls. Much has been written about the consequences, much less has been said about the essence of this phenomenon. To understand in more detail the processes occurring with small celestial bodies that met the planet Earth on their way, "PM" turned to the Institute of Dynamics of Geospheres of the Russian Academy of Sciences, where they have long been studying and mathematical modeling of the movement of meteoroids, that is, celestial bodies entering the Earth's atmosphere. And here's what we managed to find out.
Knocked out of the belt
Bodies like Chelyabinsk come from the main asteroid belt, which lies between the orbits of Mars and Jupiter. It is not so close to the Earth, but sometimes the asteroid belt is shaken by cataclysms: as a result of collisions, larger objects disintegrate into smaller ones, and some of the debris pass into the category of near-Earth cosmic bodies - now their orbits cross the orbit of our planet. Sometimes celestial stones are kicked out of the belt by disturbances caused by large planets. As the data on the trajectory of the Chelyabinsk meteorite show, it represented the so-called Apollo group - a group of small celestial bodies moving around the Sun in elliptical orbits that intersect the Earth's orbit, and their perihelion (that is, the closest distance from the Sun) is less than the perihelion of the Earth's orbit.
Since we are most often talking about debris, these objects have an irregular shape. Most of them are composed of a rock called "chondrite". This name was given to her because of chondrules - spherical or elliptical inclusions with a diameter of about 1 mm (less often - more), surrounded by a debris or fine-crystalline matrix. Chondrites are of different types, but also iron specimens are found among meteoroids. It is interesting that there are fewer metal bodies, no more than 5% of the total, but iron certainly predominates among the found meteorites and their fragments. The reasons are simple: firstly, chondrites are visually difficult to distinguish from ordinary earth stones and are difficult to detect, and secondly, iron is stronger, and an iron meteorite has more chances to break through the dense layers of the atmosphere and not scatter into small fragments.
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Incredible speeds
The fate of a meteoroid depends not only on its size and the physicochemical properties of its substance, but also on the rate of entry into the atmosphere, which can vary over a fairly wide range. But in any case, we are talking about ultra-high speeds, significantly exceeding the speed of movement not even of supersonic aircraft, but also of orbital spacecraft. The average speed of entry into the atmosphere is 19 km / s, however, if the meteoroid comes into contact with the Earth on courses close to the oncoming one, the speed can reach 50 km / s, that is, 180,000 km / h. The smallest speed of entry into the atmosphere will be when the Earth and a small celestial body move, as it were, in neighboring orbits, next to each other, until our planet attracts a meteoroid.
Oleg Makarov