The fall of a meteorite in Chelyabinsk. Chelyabinsk meteorite: what scientists have learned in a year Chelyabinsk meteorite message
Until now, many, hearing about the history of the Chelyabinsk meteorite, ask scientists the question: why did they not find this asteroid in time? The answer is very simple - because it flew from the direction of the Sun! In his report to the Day of Space Science at the Space Research Institute of the Russian Academy of Sciences, Academician M. Ya. Marov revealed other secrets of this uninvited guest.
Secrets of the Chelyabinsk meteorite
In the program of the Day of Space Science at the Space Research Institute of the Russian Academy of Sciences, Academician Mikhail Yakovlevich Marov presented the report "Study of the Chelyabinsk Meteorite". This suggests that the study of the collision of the Earth with an asteroid from the Apollo group, whose orbits cross the Earth's orbit from the outside and are potentially dangerous for our planet, as confirmed by the event on February 15, 2013, is still ongoing and interest in the uninvited guest does not wane ...
As we remember, the entry of an asteroid with a diameter of 18 meters into the earth's atmosphere ended with the explosion of a hot meteorite body, the fall of many of its fragments of various sizes on the extended part of the trajectory completion with the final fall into Lake Chebarkul. The ice cover of the lake was broken through, and the remnants of the asteroid that have completed their flight, not yet raised to the surface, lie at the bottom. Future expeditions will find and raise the celestial guest for further research, and hot on the heels were collected fragments of the asteroid, discovered by a variety of people - from drivers on the routes to residents of Chelyabinsk and the surrounding area, as well as scientists and specialists who found themselves in the zone of a space event. The collection of cosmic material continues and will continue, since this extraordinary event provides an interesting opportunity to study matter - the building material of the solar system.
A meteorite explosion occurred over a crowded city (after all, South Ural Chelyabinsk is a million-plus city) at dawn, when many were already awake. The brightest trace in the morning sky ended in an explosion at an altitude of 23 kilometers, when the asteroid collapsed in a blinding flash! A shining brighter than the Sun made people rush to the windows. Many were injured as the shock wave shattered glass. That is why the resonance of the event was very significant - many required medical assistance. How not to remember the fall of the Tunguska meteorite! It was incomparably more massive, its fall caused a fire and fell out of forests, but in taiga and deserted places ...
M. Ya.Marov
Then there were no casualties, and if the Tunguska newcomer fell in a densely populated region, then tragic consequences would be inevitable! Therefore, the asteroid hazard is assessed by scientists and the monitoring of potentially dangerous objects is continuously carried out. There is a heading "asteroid hazard" on the Internet, and anyone can get acquainted with those objects of near space that are dangerously approaching our planet.
You may ask - why didn't they identify the asteroid that exploded over Chelyabinsk? There is an explanation: he flew from the direction of the Sun! It was very difficult, almost impossible to track his approach. The relatively small mass of the asteroid, only 11 tons, caused destruction during the explosion, and people were also injured. The response to this event all over the world has once again convinced mankind of the reality of the asteroid hazard.
According to statistics, such events occur approximately once every hundred years. The Chelyabinsk meteorite is fully consistent with the statistics, noted academician M. Ya Marov, the arrival of the Chelyabinsk meteorite after the Tunguska one is distant by approximately the same time interval. The fact established by scientists is extremely interesting - the Chelyabinsk meteorite is a fragment of a larger body that underwent impact and destruction. This is revealed by the structure of its substance, which is characterized by specific features of an inhomogeneous chemical composition, telling scientists that this substance has undergone shock heating and partial melting during collisions of asteroid bodies in the past.
In terms of composition, the asteroid is an ordinary chondrite, chondrites are divided into 3 groups depending on the iron content in olivine and pyroxene. The light and dark varieties of granules in the structure of the Chelyabinsk chondrite fragments indicate an impact melt, the history of this celestial alien can be reconstructed by studying the morphology and applying proton analysis. The veins between light granules are filled with dark and fine-grained impact melt. It is a breed from the time of the origin of the solar system, which is 4.65 billion years old.
The impact that led to the metamorphism found in the meteorite rock could have occurred at a very early stage in the formation of planetesimals - protoplanetary bodies. The study of the isotopic composition of meteorite matter suggests a second impact event, which dates back to much later dates - about 300 million years.
One or two events formed the Chelyabinsk asteroid? The question remains open for now. We can confidently say that the asteroid was crushing - the Chelyabinsk meteorite is a fragment of a larger body from the Apollo asteroid group. A breakaway fragment with a changed orbit approached the Earth and fell into Lake Chebarkul. Such small bodies - meteoroids - are elements of the history of the formation of the solar system, a direct study of their substance gives an idea of the phases of the creation of the solar system, which is extremely important.
Karapetyan Lucy
Project presentation of the study of the mystery of the Chelyabinsk meteorite.
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The fall of the meteorite in the Urals
PURPOSE OF THE PROJECT: On the basis of studying the riddle of the Chelyabinsk meteorite, introduce students to asteroids, meteorites, comets, meteoric bodies and streams, consider cosmic velocities, calculate the speed of the meteorite.
Objectives of the project: 1. To point out the connection between asteroids and meteorites, comets and meteor showers. 2. To highlight the basic information concerning the nature of meteorites, meteorites, asteroids and comets.
On February 15, 2013, at about 9:20 am, a meteoroid exploded in the vicinity of Chelyabinsk at an altitude of 15-25 km
Meteoroid Data On February 15, NASA scientists reported that the space object was 15 meters in diameter and caused an explosion with a yield of 300 kilotons of TNT. A little later, the energy output of the explosion was increased to 470 kilotons. Before entering the Earth's atmosphere, the object was about 17 meters in diameter, weighing up to 10,000 tons and moving at a speed of 18 km / s. In 32.5 seconds after entering the atmosphere, the object completely collapsed, as a result of which the released energy amounted to about 500 kilotons of TNT. According to NASA, this body is the largest since the fall of Tunguska in 1908.
The trajectory of the body falling "According to preliminary estimates, this is a space object of non-technogenic origin and qualifies as a meteoroid moving at a speed of about 30 km / s along a low trajectory."
Places of fall and searches O found the place of the alleged fall of one of the fragments of the meteorite - a funnel with a diameter of about 6 meters. ”The funnel was formed on the shore of Lake Chebarkul near Chelyabinsk. Earlier it was reported that, according to the governor of the Chelyabinsk region, a meteorite fell into the lake itself. This can be explained by the fact that the celestial body in the atmosphere was torn apart into several fragments of various sizes. According to the estimates of Czech astronomers, the most massive body of 200-500 kg fell into Lake Chebarkul, and smaller fragments should be looked for in the area of the village of Travniki and the village of Schapino.
Mineral composition Details of the chemical composition were reported by a member of the RAS Committee on Meteorites, Ural Federal University scientist Viktor Grokhovsky, stating that it is a stone meteorite, an ordinary chondrite, which contains: metallic iron, olivine, and sulfites; melting crust is also present. In the meteorite debris, analysis revealed the presence of native copper inclusions, which is unusual for LL5 chondrites.
Victims and destruction
Reaction in the country and the world The event received wide media coverage, becoming one of the most popular topics
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Introduction | ||
Goals, tasks of the project. | ||
Meteoroid data | ||
Body fall trajectory | ||
Study | ||
Mineral composition | ||
Victims and destruction | ||
Reaction in the country and the world | ||
conclusions | ||
Literature | ||
The fall of a meteorite in the Urals in 2013
Introduction: We are investigating a phenomenon that occurred on the morning of February 15, 2013 at about 9:20 am local time. The meteoroid exploded in the vicinity of Chelyabinsk at an altitude of 15-25 km. According to the number of victims (1613 people), the fall of this meteoroid has no analogues in the world documented history, but at the same time in the Chinese sources there are references to lethal cases associated with the fall of meteorites. The fall of the meteoric body aroused great interest in us.
Objectives of the project: On the basis of studying the mystery of the Chelyabinsk meteorite, get acquainted with asteroids, meteorites, comets, meteoric bodies and streams, consider cosmic velocities, calculate the speed of the meteorite.
Project objectives:
- Point out the relationship between asteroids and meteorites, comets and meteor showers. Contribute to the formation of a scientific worldview.
- Create an emotional situation, talking about the Chelyabinsk meteorite, highlight the basic information regarding the nature of meteoric bodies, meteorites, asteroids and comets.
- Demonstrate an image of a meteor shower, a bright comet, a photo report from the place where the Chelyabinsk meteorite fell.
MAIN PART
Meteoroid data
Initial estimates, the mass of the object upon entering the atmosphere was estimated at 10-100 tons, the explosion power was several kilotons, the velocity of entry into the atmosphere was 15-20 km / s, the height of destruction was 30-50 km, the height of the main energy release was 5-15 km. According toS. A. Yazeva, the explosion power was greater than that ofVitim bolide... The speed of the meteoroid during the fall ranged from 20 to70 kilometers per second. Margaret Campbell-Brown (English Margaret campbell-brown ), an astronomer from the University of Western Ontario (Canada), who studied data from infrasonic sensors for detecting nuclear tests,gave the following estimate: the diameter of the object -15 meters, weight - 7000 tons. This makes it the largest object that has hit the Earth in the past 105 years (since the fallTunguska meteorite).
A nuclear explosion or a fireball explosion in the atmosphere creates low-frequency sound waves (less than 20 Hz) that can be used to determine the parameters of an event[ ... Worldwide datainfrasonictracking stationsnuclear testing(Comprehensive Nuclear-Test-Ban Treaty Organization) showed the presence of a source of infrasonic waves inUral mountains, which made it possible to make estimates of the power. Among all the events, this was the most powerful since the commissioning of the first station in 2001. This source of infrasound turned out not to be stationary, as it would have been in a nuclear weapon test in a mine, but moved, which was noted by the change in direction to the source. The farthest station that recorded the event is located in Antarctica at 15000 km from the source.
On February 15, NASA scientists reported that the space object was15 meters in diameter and caused an explosion with a yield of 300 kilotons of TNT. A little later, the energy output of the explosion was increased to 470 kilotons. In the evening of the same day, at 7 o'clock onPacific timeOn February 15, NASA released updated data on the meteoroid based on the analysis of data from infrasonic tracking stations: before entering the Earth's atmosphere, the object was about17 meters in diameter, weighing up to 10,000 tons and moving at a speed of 18 km / s. In 32.5 seconds after entering the atmosphere, the object completely collapsed, as a result of which the released energy amounted to about 500 kilotons perTNT equivalent... According to NASA, this body significantly exceedsSikhote-Alinsky, and is the largest after the fallTunguskain 1908. EstimatedRASthe explosion power is much less, 100-200 kilotons.
Expert ESAHayner Clinkrad (English Heiner Klinkrad ) noted that the penetration of this body into the atmosphere went unnoticed, despite its massiveness, since modern telescopes are focused on searching for asteroids more100 meters in diameter. Until now, scientists have managed to predict the collision of a celestial body with the Earth only once: it was an asteroid 2008 TC.
Body fall trajectory
According to information Roscosmos, « According to preliminary estimates, this is a space object of non-man-made origin and qualifies asmeteorite(erroneous use of the term, correct - „meteoroid“) moving at a speed of about 30 km / s on a low trajectory". At the same time, in the press serviceRussian Academy of Sciences(RAS) suggested that the body weight was about 10 tons, and the diameter was several meters. According to the RAS, the meteoroid entered the atmosphere at a speed of 15-20 km per second, collapsed at an altitude of 30-50 km, and the continued movement of its fragments caused a powerful glow (bolide) and a strong shock wave. Subsequently, most of the fragments evaporated, and only a few of them reached the ground.
According to the chairman of the regional officeRussian Geographical Society, candidate of geographical sciences Sergei Zakharov, the body flew from the southeast to the northwest, the flight trajectory followedazimuthabout 290 degrees in lineEmanzhelinsk - Miass.
The reconstruction of the meteoroid trajectory by astronomers from Colombia is based on the study of records of two observation cameras, one of which is located onRevolution square in the center of Chelyabinsk and the other in Korkino, as well as the assumption about the place of the fall inLake Chebarkul... Meteoroid belongs to the groupApollo... The prediction accuracy is determined by one unknown free parameter, the distance between the Revolution area and the point on the Earth's surface over which the explosion occurred. The two extreme boundaries of 50 and 72 km lead to some uncertainty in the parameters of the trajectory: the explosion height from 32.5 to 46.7 km, the meteoroid velocity from 13.4 to 19.6 km / s.
Study
The meteoroid was not detected before it entered the atmosphere. In the case of a celestial body with such a size,albedoand the trajectory of movement around the planet, the capabilities of modern optical instruments did not allow determining its approach more than two hours before its destruction above the earth.
The RAS Committee on Meteorites entrusted the research work of the Meteorite ExpeditionUral Federal Universityunder the leadership of Mikhail Larionov. On February 16 and 17, scientists examined the alleged fall sites of the meteorite debris, and collected several fragments of black rock ranging in size from 1 to 7 mm, presumably the remnants of the meteorite. They were sent for research in the laboratory of UrFU.
On February 16, the vice-governor of the region, Igor Murog, said that during the search for meteorite fragments nothing was found, and the search had been stopped. He also came to the conclusion that "the polynya, which was found on Lake Chebarkul and was originally taken for the place where the meteorite debris fell, was formed for a different reason."
However, on February 17, the expeditionUrFUreported the finding of 53 particles of meteorite rock in the area of Lake Chebarkul, despite the fact that scientists were not allowed directly to the ice hole Scientists decided to name the meteorite by the name of the nearest settlement from the place of the first finds - Chebarkul.
According to Mikhail Nazarov, the meteorite belongs to a rare type of ordinary chondrites LL5, shock fraction S4, degree of weathering W0. In space, a meteorite collided with another celestial body, as indicated by melting veins found in meteorites.
On February 19, the second expedition of scientists took place, this time through settlements south of the city of Chelyabinsk. We managed to find larger fragments with a total mass of up to 1 kg,structurewhich corresponds to the samples collected on the ice of Lake Chebarkul. They will allow for better research.
On February 24, the UrFU expedition found fragments of a meteorite, the largest fragment weighing 1.8 kg.
On March 5, scientists from UrFU reported on a preliminary analysis of the map of the distribution of the magnetic field module, compiled with the help of high-precision magnetometers, at the supposed place of the fall of a large fragment of the Chelyabinsk bolide in Lake Chebarkul. According to Viktor Grokhovsky, the meteorite has lost its integrity and consists of several large fragments with a total mass of about 100 kg.
According to Erik Galimov, the Chelyabinsk meteorite was part of a larger asteroid, but broke away and several tens of millions of years ago experienced a collision with another celestial body as a result of cracks that did not allow determining the age unambiguously.
5
Mineral composition
Details on the chemical composition were reported by a member of the RAS Committee on meteorites, a scientist of the Ural Federal UniversityVictor Grokhovskystating that it is a stone meteorite,common chondrite, which includes: metaliron, olivine, and sulfites; bark is also presentmelting... In the fragments of the meteorite, analysis revealed the presence of an inclusion of nativecopperwhich is unusual for LL5 chondrites. It was also noted that earlier such large inclusions - more than 100micron- not found in meteorites.
Meteorite composition | ||
Mineral | Formula | Notes (edit) |
(Mg, Fe) 2 SiO 4 | The foundation |
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(Mg, Fe) 2 Si 2 O 6 | the foundation |
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Impurities |
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(Ni, Fe) 3 S 2 | Impurities |
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alpha- (Fe, Ni) | Impurities |
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gamma- (Fe, Ni) | Impurities |
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(Fe, Mg) Cr 2 O 4 | Impurities |
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CaMgSi 2 O 6 | Impurities |
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(Ca, Na) Al 2 Si 2 O 8 | Impurities |
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Feldspar glass | Impurities |
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FeTiO 3 | ||
Ca 5 (PO 4) 3 Cl | ||
Ca 9 NaMg (PO 4) 7 |
Analysis of meteorite fragments found near the village of Emanzhelinka carried out inSB RASallowed 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 glass, which fills large cracks in Chelyabinsk. In addition, the glass contains impurities of silicates, etc., and the 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.
Victims and destruction
By 21:00 Moscow time, it became known that the number of victims from flying debris (primarily glass fragments) caused by a shock wave from an explosion of a meteoric body in the Chelyabinsk region was 1142 people, 48 of them were hospitalized, including 13 children. A 52-year-old resident of Kopeysk suffered a serious spinal injury when falling from a staircase and was brought in by forceMinistry of Emergency Situationsto Moscow, but on March 1 she was discharged. The day after the explosion, 40 people remained in the hospital, including three children. In total, 1,613 people went to hospitals in the Chelyabinsk region with injuriesof which 69 people were hospitalized. The number of injured children amounted to 324 of which 13 were hospitalized. Due to the large number of calls, doctors went on additional shifts, and the regional health ministry began to work around the clock.
It was decided to cancel classes in schools and kindergartens, since as a result of the impact of the shock wave many buildings and structures were damaged, the glazing was broken, said the chief state sanitary doctor of the Russian Federation.Gennady Onishchenko... In Chelyabinsk itself, classes in universities have been canceled for two days. INKrasnoarmeisk ... In 72 hours from the moment of the explosion, about 400 videos of this event became available, which were viewed more than 100 million times with the most popular video RussiaToday, which was viewed more than 23 million times. Thus, videos dedicated to the events in Chelyabinsk gained 100 million views in the shortest time in history. Also, this event holds the record for the number of views in one day 73.3 million times.
As a sign of respect for the victimsGoogleremoved animation from the special versionyour logo, in which, on the eve of the expected approach of the asteroidDarvaza(Turkmenistan), behind the funnel from the collision of the meteorite with the Earth.
Conclusions:
- As a result of working on the project, we learned a lot of information about meteorites, fireballs, asteroids and other celestial bodies.
2. The project develops a cognitive interest in such a subject as astronomy. Forms a scientific outlook, develops speech, the ability to present the results of his work in front of the audience.
Used Books:
On February 15, 2018, the Historical Museum celebrates the fifth anniversary of the Chelyabinsk meteorite falling to the ground. Let us recall five interesting facts from the history of the "space guest", which since November 2013 has been a key exhibit of the State Historical Museum of the Southern Urals, representing a world cultural and historical value as a participant in a significant historical event and as a valuable item.
1. According to the Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences, the age of the meteorite is 4.45 billion years. This means that it is actually the same age as the solar system. The composition of the Chelyabinsk meteorite is dominated by ordinary chondrites of the LL5 type. On the territory of Russia, falls of such meteorites were not previously observed, and it can be assumed that the Chelyabinsk event is the most grandiose fall of chondrite LL5.
2. The weight of the Chelyabinsk meteorite lifted on October 16, 2013 from Lake Chebarkul is about 650 kilograms. The total weight of the collected debris is over 1,300 kilograms. Thus, the record was broken for the chondritic meteorite Knyaginya weighing 500 kilograms (Ukraine, 1866), which is kept in the Vienna Museum of Natural History, as well as the Paragould meteorite weighing 408 kilograms (USA, Arkansas, 1930).
3. An event similar to the fall of the Chelyabinsk meteorite occurs approximately once a century. But our event is unique in that for the first time in the history of mankind, the fall of a cosmic body was captured by hundreds of cameras and video recorders. More than 400 videos were available 72 hours after the meteorite hit, collecting more than 100 million views on the world's networks in the shortest possible time. In addition, this event holds the record for the number of views in one day - 73.3 million.
4. Employees of NASA called Chelyabinsk the luckiest city on the planet - it survived the explosion, whose power is equivalent to the power of about twenty atomic bombs that fell on Hiroshima. This is 460 kilotons of TNT. The shock wave circled the Earth twice. The explosion affected settlements in 11 municipal districts of the Chelyabinsk region, more than 7,500 buildings were damaged. About one and a half thousand people received various injuries, but, fortunately, there were no human casualties.
5. The Chelyabinsk meteorite twice acted as a "movie star". His flight, recorded by video recorders, can be seen in the films "Edge of the Future" and "War of the Worlds Z". The fall of the Chelyabinsk meteorite also formed the basis of the plot of the Russian version of the TV series "Waste".
Yuri Bogatenkov
Exactly five years ago, on February 15, 2013, residents of the Chelyabinsk region saw a bright flash in the sky. Many mistook her for a crashed plane or satellite and did not immediately recognize that a meteorite had exploded over the region. It split into dozens of fragments, the search for which continues to this day. Vladimir Busarev, a leading researcher at the Department of Moon and Planetary Research at the Sternberg State Astronomical Institute, told MIR 24 why the Chelyabinsk meteorite miraculously survived and how to behave if you suddenly find a fragment of a space body.
- Thousands of meteorites fall on the Earth every year. Why was Chelyabinsk so popular?
We first observed a case when an ordinary chondrite fell to the Earth, and even in such a large volume. The weight of the fragments that reached the Earth exceeded 650 kilograms. This is a rather rare type of meteorite, which is why it is considered a find. It is also important that the Chelyabinsk meteorite was found relatively quickly - six months after the fall, and began to study immediately. Stones that have lain for some time on the surface of the Earth are of lesser value. They have already definitely undergone changes that are characteristic only for terrestrial conditions, but not for cosmic matter. So, on the largest fragment of a meteorite that fell into Lake Chebarkul, living microorganisms of terrestrial origin were found. But this cannot be said to have hindered research.
- How did these bacteria get there?
The largest fragment of the meteorite lay at the bottom of the lake for six months. It turned out that he had pores through which he was saturated with earth water, and with it bacteria penetrated to the surface of the fragment. However, we cannot say that the origin of microorganisms is extraterrestrial, because we are dealing with a substance that has been contaminated in terrestrial conditions. The Chelyabinsk meteorite has no signs of extraterrestrial life. This can be said for sure, even though not all of the fragments have yet been recovered from the bottom of the lake.
- Colleagues from the Ural University presented you with a sample of the Chelyabinsk meteorite. Tell us about it.
It is small, weighing several tens of grams. We studied it in the laboratory. We looked at its reflective characteristics, the composition of the substance. We were convinced that this is a stone meteorite, it consists of the so-called ordinary chondrite. The iron content in it is small, not more than 20 percent. These types of stone meteorites are rare. They have poor "survival" because they are less tolerant of passage through the earth's atmosphere. That is, they are very fragile. In general, we have studied all the known meteorites only by a quarter. Therefore, space projects for the delivery of samples from the Moon or Mars are of great interest. Only original cosmic matter can give complete information about the origin of a particular planet in the solar system or an asteroid.
- Because of this fragility, the explosion occurred?
Yes, the fragments of the Chelyabinsk meteorite show that its body is non-monolithic, it cracked while flying towards the Earth. If the body were monolithic, perhaps the explosion would not have occurred, and a fragment of a larger mass would have fallen to the earth's surface. Eyewitnesses said they heard a series of explosions, but in reality there was only one explosion. It was just that the sound had a whole spectrum of waves. The acoustic effect was like a thunderclap: at first the sound is weak, then it gets stronger. It seemed to people that there were several explosions. The fact is that fragments of the meteorite entered the atmosphere at supersonic speed, and there were many of these fragments. This explains the unusual sound effects.
- Why was the meteorite called Chelyabinsk and not Chebarkul?
Initially, they wanted to call it Chebarkul. But the fact is that only the largest fragment of the meteorite fell in Chebarkul. The substance, the fragment of which is the Chelyabinsk meteorite, dispersed outside this settlement over a fairly large area. Therefore, the scientific community decided to emphasize in the title that the fall of the cosmic body occurred in the Chelyabinsk region and does not concern only Chebarkul.
- And what is known about the cosmic body from which the Chelyabinsk meteorite broke away?
It is approximately 4.5 billion years old. About 300 million years ago, it collided with other cosmic bodies. The violent collision led to fragmentation and the formation of a secondary body, which, in turn, was also fragmented. The fact of the collision is confirmed by jadeite - a greenish mineral that is found in the Chelyabinsk meteorite. It only forms at high temperatures and pressures, a bit like jade, a mineral used to make jewelry.
Particularly enterprising residents of Chelyabinsk have repeatedly tried to sell the fragments of the famous meteorite. How do you feel about this behavior?
Scientists, in principle, have a negative attitude towards this type of fraud and urge all people who find meteorites to submit them for research. So, the fragments of the Chelyabinsk meteorite must first of all be given to the Chelyabinsk State University. Also in Moscow at the Vernadsky Institute of Geochemistry and Analytical Chemistry there is a committee on meteorites. It should be understood that scientists always have the opportunity to obtain some valuable information about meteorites. Any such finds are of scientific interest to us, and the state is ready to pay for them.
- Which of the fallen meteorites in Russia is considered the most mysterious?
Perhaps Tunguska. There are no debris left of it, so no one knows exactly what this meteorite was. I can assume that it was a meteorite of primitive ice composition. The sharp heating in the Earth's atmosphere led to a thermal explosion. If you remember, this explosion was accompanied by a powerful glow. It was as strong as in a nuclear explosion. Until now, there is an assumption that it was not a meteorite, but a nuclear explosion. But this is not so, because no products of thermonuclear reactions were found on the spot. You can learn more about the Tunguska meteorite, but for this you need to conduct a study of a large territory in the permafrost of the impassable taiga using highly sensitive equipment. This is not easy to organize. In addition, if any isotopes are found there, they must be studied immediately on the spot. It is very difficult to transport them. If we were able to conduct a long-term expedition, we would have learned something new about the Tunguska meteorite.
At the time of entry into the Earth's atmosphere, the Chelyabinsk meteorite weighed 13 thousand tons and was the size of a seven-story building. Among the meteorites that fell in Russia, it became the largest after the Tunguska. Scientists have found that the meteorite entered the atmosphere at a speed of 19 kilometers per second. Part of the fragments, approaching the Earth, collapsed and burned up in the atmosphere. The shockwave dropped out in many glass buildings and shattered the cladding. About a thousand people were injured of varying severity. Material damage to the region from the fall of the meteorite exceeded one billion rubles. The largest fragment of the meteorite has become an exhibit of the State Historical Museum of the Southern Urals. Everyone can touch it.
Most often meteorites fall in Antarctica. According to experts, about 700 thousand of them are scattered on the mainland. The largest meteorite is called Goba, it was discovered in Namibia in 1920. Its weight exceeds 60 tons.
MOSCOW, February 14 - RIA Novosti. A year ago, on February 15, 2013, residents of the southern Urals witnessed a cosmic catastrophe - an asteroid fall, which was the first such event in history that caused serious damage to people.
In the first moments, the inhabitants of the region talked about the explosion of an "incomprehensible object" and strange flashes. Scientists have been researching this event for a whole year, which they managed to find out at this point - read the RIA Novosti review.
What was it?
In the region of Chelyabinsk, a rather ordinary space body fell. Events of this magnitude occur once every 100 years, and according to some sources - and more often, up to five times a century. Scientists believe that bodies of about ten meters in size (about half the size of the Chelyabinsk body) fly into the Earth's atmosphere about once a year, but this happens most often over oceans or over sparsely populated regions. Such bodies explode and burn at high altitudes without causing any harm.
The size of the Chelyabinsk asteroid before the fall was about 19.8 meters, and the mass - from 7 thousand to 13 thousand tons. According to scientists, a total of 4 to 6 tons fell to the ground, that is, about 0.05% of the original mass. Of this amount, no more than 1 ton has been collected at the moment, taking into account the largest fragment weighing 654 kilograms, raised from the bottom of Lake Chebarkul.
Geochemical analysis showed that the Chelyabinsk space object belongs to the type of ordinary chondrites of the LL5 class. Chondrite is one of the most common types of stone meteorites, about 87% of all found meteorites belong to this type. They are distinguished by the presence in the thickness of rounded grains of millimeter size - chondrules, which consist of a partially melted substance.
Expert: the largest fragment of the Chelyabinsk meteorite weighs 654 kgThe exact weight of the largest fragment of the Chelyabinsk meteorite, which was recovered from the bottom of Lake Chebarkul in mid-October 2013, was 654 kg, the director of the company that carried out the operation to raise the meteorite told reporters.The data from infrasound stations indicate that the power of the explosion that occurred at the moment of a sharp deceleration of the Chelyabinsk asteroid at an altitude of about 90 kilometers was from 470 to 570 kilotons in TNT equivalent - this is 20-30 times more powerful than a nuclear explosion in Hiroshima, but more than ten times less power of the explosion at the time of the Tunguska catastrophe (from 10 to 50 megatons).
The place and the time made this fall unique. This is the first ever case of a large meteorite falling in a densely populated area, so never before has a meteorite fall caused such serious damage - 1.6 thousand people turned to doctors, 112 were hospitalized, glass was broken in 7.3 thousand buildings.
Thanks to this, scientists have obtained a huge amount of data about the event - this is the best documented meteorite fall. As it turned out later, one of the video cameras captured even the moment the largest fragment fell into Lake Chebarkul.
Where did this come from?
Scientists answered this question almost immediately: from the main asteroid belt of the solar system, the region between the orbits of Mars and Jupiter, where the trajectories of many small bodies pass. The orbits of some of them, in particular the asteroids of the Apollo or Aton group, are elongated and can cross the earth's orbit.
Due to the fact that the flight of the Chelyabinsk bolide was recorded on many video recordings and photographs, including satellite images, astronomers could quite accurately reconstruct its trajectory, and then try to continue this line back behind the atmosphere in order to build the orbit of this body.
Attempts to restore the trajectory of the Chelyabinsk body before the collision with the Earth were undertaken by various groups of astronomers. Their calculations showed that the semi-major axis of the orbit of the Chelyabinsk asteroid was about 1.76 astronomical units (the average radius of the earth's orbit), the perihelion (the point of the orbit closest to the Sun) was at a distance of 0.74 units, the aphelion (the most distant point) was at 2 , 6 units.
With these data in hand, scientists tried to find the Chelyabinsk asteroid in the catalogs of previously discovered small bodies. It is known that many already discovered asteroids are "lost" after a while, and some of them are opened twice. Scientists did not exclude that the Chelyabinsk object belonged to such "lost" bodies.
His relatives
Although it was not possible to find an exact match, scientists have found several possible "relatives" of the "Chelyabinsk". The group of Jiri Borovichka from the Astronomical Institute of the Czech Academy of Sciences, calculating the trajectory of the Chelyabinsk body, found that it is very similar to the orbit of the 2.2-kilometer asteroid 86039 (1999 NC43). In particular, the semi-major axis of the orbits of both bodies is 1.72 and 1.75 astronomical units, the perihelion distance is 0.738 and 0.74.
Scientists do not know why the fragments of the Chelyabinsk meteorite are of different colorsThe meteorite, later named Chelyabinsk, fell on February 15, 2013. Scientists still cannot figure out why some fragments of the meteorite are completely dark, while others are light inside.Fragments of the Chelyabinsk space body that fell to the ground "told" the scientists the story of his life. It turned out that the Chelyabinsk asteroid is the same age as the solar system. Analysis of the ratio of the isotopes of lead and uranium showed that its age is about 4.45 billion years.
However, about 290 million years ago, the Chelyabinsk asteroid experienced a major catastrophe - a collision with another cosmic body. This is evidenced by dark veins in its thickness - traces of melting of a substance with a powerful impact.
At the same time, scientists believe that it was a very "fast" process. The traces of cosmic particles - the tracks of iron nuclei - did not have time to melt, which means that the "accident" itself lasted no more than a few minutes, said specialists from the Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences.
At the same time, it is possible that traces of melting could appear during too close approach of the asteroid to the Sun, scientists from the Institute of Geology and Mineralogy (IGM) of the SB RAS believe.
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