> Chelyabinsk meteorite
Learn the history of the fall Chelyabinsk meteorite: description and characteristics of the object with a photo, force of impact, where it fell, size, where it came from, composition, age.
Five years have passed since the people of South Urals witnessed a cosmic cataclysm - the fall Chelyabinsk meteorite, which became the first case in modern history that caused significant damage to the local population.
The asteroid fell in 2013, on February 15. At first, it seemed to the South Urals that an “obscure object” had exploded; many saw strange lightning lighting up the sky. This is the conclusion reached by scientists who studied this incident for a year.
Data on the Chelyabinsk meteorite
A fairly ordinary comet fell in an area near Chelyabinsk. Falls of space objects of precisely this nature occur once every century. Although, according to other sources, they happen repeatedly, on average up to 5 times every 100 years. According to scientists, comets with a size of about 10 m fly into the atmosphere of our Earth approximately once a year, which is 2 times larger than the Chelyabinsk meteorite, but this often happens over regions with a small population or over the oceans. Moreover, comets burn up and collapse at great heights, without causing any damage.
Before the fall, the mass of the Chelyabinsk aerolite was from 7 to 13 thousand tons, and its parameters supposedly reached 19.8 m. After analyzing, scientists found out that only about 0.05% of the initial mass fell to the surface of the earth, that’s 4-6 tons. Currently, a little more than one ton has been collected from this amount, including one of the large fragments of aerolite weighing 654 kg, raised from the bottom of Chebarkul Lake.
A study of the Chelyabinsk maetorite based on geochemical parameters revealed that it belongs to the type of ordinary chondrites of class LL5. This is the most common subgroup of stony meteorites. All currently discovered meteorites, about 90%, are chondrites. They got their name due to the presence of chondrules in them - spherical fused formations with a diameter of 1 mm.
Indications from infrasound stations indicate that in the minute of strong braking of the Chelyabinsk aerolite, when approximately 90 km remained to the ground, a powerful explosion occurred with a force equal to the TNT equivalent of 470-570 kilotons, which is 20-30 times stronger than the atomic explosion in Hiroshima, but in terms of explosive power it is inferior to the fall of the Tunguska meteorite (approximately from 10 to 50 megatons) by more than 10 times.
The fall of the Chelyabinsk meteorite immediately created a sensation both in time and place. In modern history, this space object is the first meteorite to fall into such a densely populated area, resulting in significant damage. So, during the meteorite explosion, the windows of more than 7 thousand houses were broken, more than one and a half thousand people sought medical help, of which 112 were hospitalized.
In addition to significant damage, the meteorite also brought positive results. This event is the best documented event to date. In addition, one video camera recorded the phase of the fall of one of the large fragments of the asteroid into Lake Chebarkul.
Where did the Chelyabinsk meteorite come from?
For scientists, this question was not particularly difficult. It emerged from our solar system's main asteroid belt, a zone in the middle of the orbits of Jupiter and Mars where the paths of most small bodies lie. The orbits of some of them, for example, the asteroids of the Aten or Apollo group, are elongated and can pass through the orbit of the Earth.
Astronomers were able to quite accurately determine the flight trajectory of the Chelyabinsk resident, thanks to many photo and video recordings, as well as satellite photographs that captured the fall. Then astronomers continued the path of the meteorite in the opposite direction, beyond the atmosphere, in order to build the complete orbit of this object.
Several groups of astronomers tried to determine the path of the Chelyabinsk meteorite before it hit the Earth. According to their calculations, it can be seen that the semimajor axis of the orbit of the fallen meteorite was approximately 1.76 AU. (astronomical unit), this is the average radius of the Earth's orbit; the point of the orbit closest to the Sun - perihelion, was at a distance of 0.74 AU, and the point most distant from the Sun - aphelion, or apohelion, was at 2.6 AU.
These figures allowed scientists to try to find the Chelyabinsk meteorite in astronomical catalogs of already identified small space objects. It is clear that most of the previously identified asteroids, after some time, “fall out of sight” again, and then some of the “lost” ones manage to be “discovered” a second time. Astronomers did not reject this option, that the fallen meteorite may be the “lost one.”
Relatives of the Chelyabinsk meteorite
Although complete similarities were not revealed during the search, astronomers still found a number of probable “relatives” of the asteroid from Chelyabinsk. Scientists from Spain Raul and Carlos de la Fluente Marcos, having calculated all the variations in the orbits of the “Chelyabinsk”, found its supposed forefather - asteroid 2011 EO40. In their opinion, the Chelyabinsk meteorite broke away from it for about 20-40 thousand years.
Another team (Astronomical Institute of the Academy of Sciences of the Czech Republic) led by Jiri Borovička, having calculated the glide path of the Chelyabinsk meteorite, found that it is very similar to the orbit of asteroid 86039 (1999 NC43) with a size of 2.2 km. For example, the semimajor axis of the orbit of both objects is 1.72 and 1.75 AU, and the perihelion distance is 0.738 and 0.74.
The difficult life path of the Chelyabinsk meteorite
Based on the fragments of the Chelyabinsk meteorite that fell to the surface of the earth, scientists “determined” its life history. It turns out that the Chelyabinsk meteorite is the same age as our solar system. When studying the proportions of uranium and lead isotopes, it was found that it is approximately 4.45 billion years old.
His difficult biography is indicated by dark threads in the thickness of the meteorite. They arose when substances that got inside as a result of a strong impact melted. This shows that approximately 290 million years ago this asteroid survived a powerful collision with some kind of space object.
According to scientists from the Institute of Geochemistry and Analytical Chemistry named after. Vernadsky RAS, the collision took approximately several minutes. This is indicated by leaks of iron nuclei that did not have time to completely melt.
At the same time, scientists from the Institute of Geology and Mineralogy SB RAS (Institute of Geology and Mineralogy) do not reject the fact that traces of melting may have appeared due to the excessive proximity of the cosmic body to the Sun.
The fall of a celestial body, which became unique thanks to eyewitnesses.
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Chelyabinsk meteorite. Photo by AFP
On February 15, 2013 at 7:22 Moscow time (9:22 local) a meteorite crashed in the Chelyabinsk region. The celestial body was also seen by residents of Bashkiria, Tyumen, Sverdlovsk, Kurgan regions and even Kazakhstan.
The fall of a cosmic body by hundreds of witnesses on phone cameras and video recorders. Pictures of eyewitnesses from almost all the world's news channels.
Initially, NASA experts said that the Chelyabinsk meteorite was the largest since. The incident caused serious damage to Chelyabinsk and its suburbs: 7 thousand buildings were damaged, in which 120 thousand families lived. More than a thousand local residents were injured. Damage amounted to 1.2 billion rubles.
And a large number of visual evidence of the phenomenon made the Chelyabinsk meteorite unique long before the scientists’ conclusions.
What happened then
Photo by NASA/M. Akhmetvaleev
On the morning of February 15, a meteorite measuring 17-19 meters and weighing 10-13 thousand tons entered the atmosphere at a speed of 18-19 kilometers per second.
Above the Earth, it appeared near the border of Russia and Kazakhstan. The meteorite was not seen on asteroid observation systems due to its acute angle relative to the Sun and small diameter.
Along with the fall, there is a light flash and electromagnetic radiation. The meteorite disintegrated approximately 30 seconds after entering the atmosphere at an altitude of 30-50 kilometers. It looked like a series of explosions and shock waves. Seismic stations recorded earthquakes.
Broken windows in a university building
The first eyewitnesses to see an unknown object in the sky talk about various reasons: from a falling plane (both civilian and military) to missiles and enemy bombing.
Soon the conspiracy theories disappeared, and meteorite fragments began to be found in different places in the Chelyabinsk region.
Local authorities, along with residents, were discouraged by the unusual phenomenon and sometimes did not realize what was being said.
The largest part of the celestial body, weighing 654 kilograms, was removed from Lake Chebarkul in the fall of 2013. At the same time, scientists and local residents collected up to 100 kilograms of small fragments.
In the International Catalog of Meteorites, a fireball under the official name “Chelyabinsk”.
The largest piece of meteorite raised from the bottom of Lake Chebarkul. Photo: Science/AAAS
What exactly fell to Earth
Experts have identified a cosmic body as one of the most common types of stony meteorites: events of this magnitude are expected once every 100 years or even more often. The celestial body is from a larger one about 290 million years ago and came from the main asteroid belt of the Solar System, which is located between the orbits of Jupiter and Mars.
According to the Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences, the meteorite turned out to be 4.45 billion years old, which is approximately equal to the solar system. This age of some breeds of the “mother” body is also discussed at the US Institute for Lunar and Planetary Research.
The family of this celestial body, as scientists explained, could have been a 10-kilometer asteroid that fell to Earth 65 million years ago and destroyed the dinosaurs.
What did the meteorite become?
The meteorite attracted the attention of scientists around the world who studied the celestial body’s mineral, trajectory and other parameters. Scientific groups 3D model of the car and its dive to the bottom of the lake.
Russian scientists say that after the incident, a “stratospheric dust belt” formed around the planet for three months, which, however, did not affect the weather. In the dust, which came into the hands of specialists, there are “threads” similar to those formed during emissions of volcanic lava.
At the Institute of Astronomy of the Russian Academy of Sciences, to develop a system for early detection of any dangerous celestial bodies that may collide with the Earth. Russian scientists wanted to learn about such phenomena as in Chelyabinsk in three days in order to have time to evacuate local residents and secure the infrastructure. At the same time, the Federal Space Program does not include funds for such a system until 2025.
→Meteor falling
Meteorite cut through the earth's atmosphere on February 15, 2013 over the city of Chelyabinsk. The approximate weight of the meteorite was later determined to be 10 thousand tons. At great speed it streaked across the sky over the city and split into many pieces. The townspeople not only heard a powerful explosion, but also felt the scorching heat of the blast wave. The windows of many houses and institutions were broken, power lines stopped functioning, and destruction affected the entire city. The suddenness of the appearance of the “space alien” is due to the fact that it fell from the direction of the sun and thus was not visible through telescopes. The largest parts of the meteorite fell into Lake Chebarkul and therefore no more harm was caused to human lives and the city. Undoubtedly, if the debris had fallen on the city, casualties would have been inevitable - they were flying at such speed.
Meteorite debris
The meteorite split into many pieces. The largest ones fell into the lake, while the smaller ones fell many kilometers around and inside the city. Since a state of emergency was immediately declared in the city, not only emergency situations teams were sent to the site, but also experts. The fragments subjected to analysis did not immediately reveal their secret. In addition, the smallest particles needed to be collected, and many people wanted to leave their finds as a souvenir, and therefore the process of collecting the smallest particles over such a large area became more complicated. Some parts were found near remote villages, and attempts to find meteorite fragments in the lake were unsuccessful, and on the contrary, they raised doubts whether there were meteorite fragments there - the divers' report was so pessimistic. However, chemical analysis was successfully carried out on the materials found.
Chemical composition of the meteorite
An analysis of meteorite fragments found near the village of Yemanzhelinka, carried out at the SB RAS, made it possible to determine the composition more accurately. The mineral composition was found to be close to that of other LL5 chondrites, such as Hautes Fagnes, Belgium and Salzwedel, Germany. These chondrites do not contain the glass that fills the large cracks in Chelyabinsk. In addition, the glass contains impurities of silicates and other substances, and its composition is similar to the melting crust, the thickness of which is about 1 mm. Ilmenite, also not found in other LL5 chondrites, was found in small quantities in the Chelyabinsk meteorite. The melting crust contains pentlandite (Fe,Ni)9S8, godlevskite (Ni,Fe)9S8, awaruite Ni2Fe-Ni3Fe, octium, iridium, platinum, hibbingite Fe22+(OH)3Cl and magnetite Fe2+Fe23+O4. The glass contains 10-15 µm globules of heazlewoodite and godlevskite composition, which appeared after crystallization of the Fe-Ni-S sulfide melt. In the unmelted parts of small fragments at the boundary between troilite and olivine, pentlandite is sometimes present, which, apparently, is the only copper concentrator. At the grain boundaries between olivine, orthopyroxene, and chromite, chlorapatite and merrillite grains with sizes of 100-200 μm were found. Chondrules are >1 mm in size and have a heterogeneous composition. Hibbingite Fe2(OH)3Cl was also discovered, which appears to be of cosmic origin, unlike iron, which can oxidize and chlorinate through long-term interaction with soil water, because it was found in the central part of the meteorite fragment. The melting crust contains wustite FeO with admixtures of Ni, Mg, and Co oxides according to energy-dispersive X-ray spectroscopy.
The result of the examination, naturally, is understandable only to professionals, but we present it with the desire to show how extraordinary the composition of the meteorite is.
Exploration of Lake Chebarkul
On October 16, exploration of the lake for the meteorite that disappeared in it was crowned with success. An operation was carried out to lift the largest meteorite fragment. Employees of Chelyabinsk State University participated in the recovery in order to identify the meteorite. The largest fragment recovered weighs approximately 570 kg, information is not accurate due to the fact that the scales broke when trying to weigh the fragment. During the ascent, the meteorite fragment was damaged and all that remained of it was one large piece with a diameter of about 80 cm and several small ones. In addition, 4 more fragments weighing from 900 grams to 5 kg were extracted from the lake; the fragments were handed over to scientists for study and further research. Traces of rust and dents, as well as characteristic melting, indicated that the fragments found belonged to a meteorite.
The meteorite still holds many mysteries, but has already begun to share its secrets.
How and when was the Chelyabinsk meteorite formed, what class of meteorites does it belong to, what minerals are included in its composition?
Dmitry Badyukov, deputy head of the Meteoritics Laboratory at the Institute of Geochemistry and Analytical Chemistry named after A. V.I.Vernadsky RAS, where these studies are carried out.
Dmitry Dmitrievich, how many samples of fragments of the Chelyabinsk meteorite and what size are being studied in your laboratory?
The total weight of all samples that are in our laboratory is approximately 2.5 kg. The largest sample weighs 230 grams (a gift from local residents), several pieces weigh a little more than a hundred grams, other samples weigh 20-30 grams or less.
-What class of meteorites can the Chelyabinsk meteorite be classified as?
The Chelyabinsk meteorite belongs to the type of ordinary chondrites; it is a stony meteorite; they make up the majority of the flow of stony meteorites. Type LL5. The abbreviation LL means that it is quite low in iron and other metals relative to other ordinary chondrites. Number 5 is a petrological type that describes the manifestation of thermal metamorphism.
Type LL5 in the stream relative to the total number of stony meteorites is only 2%, which is not so much.
-What are ordinary chondrites?
Ordinary chondrites are space rocks that consist of so-called chondrules - these are spherical bodies ranging in size from tenths of a millimeter to several millimeters, which are located in the so-called matrix, which consists of the same material as chondrules.
-Can we now say how and when this meteorite was formed?
The age of the Chelyabinsk meteorite is approximately 4.5 billion years. Moreover, all ordinary chondrites are of a similar age. And it formed in the asteroid belt.
After the asteroid was formed as a result of accretion of substances, it was heated. The Chelyabinsk meteorite comes from areas close to the center of this asteroid, and it was very hot. Now we can say that our meteorite has a heating stage 5 (this is the fifth petrological type) (there are 6 heating stages of chondrites in total). This figure is abbreviated LL5. The dimensions of this asteroid from which the meteorite originates are unknown, but it can be assumed that it is hundreds of kilometers.
Another interesting feature is that the asteroid this piece came from experienced a strong impact. Apparently, another massive cosmic body crashed into it, which produced an impact transformation. This is the phenomenon of so-called impact metamorphism, as a result of which veinlets of impact melt were formed. When this happened is still unclear. The collision most likely occurred in the asteroid belt.
-How did you manage to find out all these details?
Based on the results of an analysis of the chemical composition of the main minerals and structural features that are visible under a microscope.
-What is the composition of the meteorite?
The composition of the Chelyabinsk meteorite samples is similar to the composition of those meteorites that are in our collection. Our research has shown that the main minerals that make up it are olivine, pyroxene, plagioclase, sulfite, kamacite and taenite. Minor minerals – chromite, apatite.
- Was the Chelyabinsk meteorite a monolithic formation or consisted of an accumulation of rocks?
Most likely, it flew in one piece, and then it fragmented in the atmosphere. Apparently, it was fragile; in the upper layers of the atmosphere at a distance of 40 to 20 km it experienced fragmentation, then the fragments scattered over a large area.
-Can we now say something about how these fragments were distributed over the surface of the Earth?
According to preliminary estimates, the length of the scattering ellipse is more than 100 km. It starts south and west of Chelyabinsk, and ends in the Zlatoust area. The width of the scattering ellipse is approximately 20 km at its widest part.
This is one of the largest known scattering halos. In general, in the history of mankind, the fall of the Chelyabinsk meteorite is the largest event. And for the first time, this event brought significant material and physical damage to people.
-Where do you think the remaining fragments of the meteorite may be located?
Only a very small part fell near Chelyabinsk; the bulk flew forward to the west. The debris may be scattered throughout the scattering ellipse, and large debris may be located at a latitude just south of Chelyabinsk in the area of the city of Yemanzhelinsk and further along a straight line of sublatitudinal strike (it can be inclined to the north or south).
The bulk of the debris probably fell to the west of Yemanzhelinsk. There is a possibility that the meteorite could have broken up, I believe, into pieces weighing tens, hundreds of kilograms, and there is a chance of finding them. It is likely that one of the fragments fell into Lake Chebarkul, but there is no information about this, and work needs to be done.
-What is the interest of large meteorite fragments to scientists?
So far we see fairly monotonous material. But the meteorite body may be a breccia, meaning there may be other types of meteorites present. That is, it is always interesting to find a large fragment, since there may be other substance present there. In addition, there is more material from which it is more convenient to reconstruct history. And finally, it is a natural heritage that can be exhibited in museums.
-What further research do you plan to conduct?
We are planning a more detailed determination of the chemical composition of the samples, including the determination of trace elements, minor elements, and determination of the isotopic composition. After the research is carried out, an application will be submitted to the meteorite committee with a request to give the meteorite the name “Chelyabinsk”.