Star of the Apocalypse - meteorites, asteroids
The world that surrounds us is full of paradoxes, and huge boulders of asteroids arriving from space are able not only to carry "spores of life" across the Universe, changing the course of evolution of living matter, but also to extinguish the fragile fire of reason. For a long time, all kinds of media have been playing on the rudimentary fears of people about impending cosmic catastrophes, while now they are doing it in a rather scientific way. After the revived dinosaurs, UFOs and sinking ships, predictions of comets and other large-scale cosmic disasters began to appear more and more in print. Similar themes appear in the cinema, for example, in the famous blockbusters "Meeting with the Abyss" and "Armageddon".
The plots in this kind of films are unpretentious, but effective: an incredible asteroid is approaching our planet. Most people will not survive a future catastrophe, as dinosaurs and lizards could not survive this kind of collision of the Earth with a meteorite tens of millions of years ago. Scientists in alliance with heroic astronauts are trying to prevent disaster, but, despite the efforts made, part of the celestial body still ends up in the Atlantic Ocean, allowing computer graphics and special effects engineers to show their art.
Of course, this is all pure fantasy, but let's think about it - but in reality, how real can a collision of the Earth with a huge meteorite be and what are the consequences of this catastrophe?
Two-thirds of our planet is occupied by seas and oceans, as a result, it is more likely that a celestial body will fall into the World Ocean. From such a blow, a powerful wave will appear - a tsunami. More than half of the world's major cities are located on the coast. 1992 - the American space agency NASA prepared a report where it was said that a giant wave would be generated from the fall of a comet or asteroid into the ocean; which, having collapsed on the coast, will destroy all living things. Even objects with a diameter of 200 to 1000 m are dangerous.
Astronomers believe that every two and a half centuries an asteroid with a diameter of at least one hundred meters falls into the ocean, causing a powerful tsunami. But geophysicists from the United States have shown that the waves generated when an asteroid falls into the ocean are much shorter than the waves that appeared as a result of an underwater earthquake. Therefore, they usually fade away before they reach the coast; moreover, their height is insignificant. Based on a computer model and calculations, meteorologists tried to estimate the scale of the disaster, taking into account the population density in coastal areas. The researchers concluded that approximately 1% of the population may be in danger, which is significantly less than previously thought. In the calculations of their colleagues, the population at risk was tens of millions of people. The danger grewif the coast is not protected by any natural or artificial barrier.
2004, autumn - German geologists discovered the trail of a giant wave that swept across the ocean about 200 million years ago. Traces of a prehistoric catastrophe were found in the layer of rock, and the height of this wave could probably reach several thousand meters. Perhaps the wave, which was caused by the fall into the ocean of one or several asteroids, passed through most of the Northern Hemisphere, destroying 3/4 of all animal species that inhabited the Earth.
The potential meteorite threat of the destruction of large cities or devastating tsunamis has always existed, because, in fact, our planet is simply surrounded by a dense swarm of asteroids. Since the 1930s, when the asteroid Hermes flew close to the Earth, whose diameter was one and a half kilometers, more than two dozen large objects were noted that approached our planet at an extremely dangerous distance. In addition, the diameter of some of them was more than a hundred meters!
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However, as mentioned above, an asteroid is not always a threat. After all, it was probably the asteroids that brought life to Earth, which began with organic molecules of their cosmic gas and dust clouds.
Approximately 450 million years ago, the consequences of a terrible explosion interrupted the reign of trilobites - the most diverse arthropod inhabitants of the World Ocean. Then, 80 million years later, at the end of the Paleozoic period, the next global catastrophe, also caused by the fall of an asteroid, ended the reign of corals and fish. But probably the worst catastrophe in the history of our planet happened 250 million years ago. As a result, the sky over the Earth has been covered with impenetrable dust clouds for many millennia.
When the sky cleared, it turned out that out of the large army of reptiles that had filled the land by the time of the catastrophe, only a few species survived. Instead of dead organisms, therapsids have bred on the renewed Earth - creatures already quite close to mammals. But even these creatures have evolved only two tens of millions of years. The ark of our planet again ran into a certain celestial reef or iceberg. Therapsids became extinct, they were replaced by dinosaurs, the famous Jurassic period, so well known to us from Spielberg's wonderful cinematic epic "Jurassic Park", came.
The famous science fiction writer Harry Garrison in the series of novels "The West of Eden" clearly showed what would have happened to humanity if 65 million years ago another giant meteorite had not crashed into our planet. Dinosaurs became extinct, and eventually the era of mammals came.
Thus, an asteroid several hundred meters in diameter was enough to destroy European civilization. But there are celestial bodies that are much larger. It turns out that shots from disaster films are not so much science fiction as a model of the likely course of events.
Usually, asteroids are negligible - from a few millimeters to several centimeters, but according to statistics, every 200 years our planet meets with cosmic bodies several tens of meters in diameter. And such a "flying rock" is quite capable of wiping out a multimillion city from the face of the earth in a few seconds.
What can be done to prevent such meetings?
To begin with, it is necessary to build an interconnected international system for observing outer space inside the solar system, in which a powerful central computer should be connected to dozens of space and ground-based telescopes that register all large bodies that appear near the earth's orbit. When detecting meteorites and comets, it is necessary to immediately calculate their flight trajectory and thus determine whether they can pose a potential danger to our planet.
In our time, there is a whole network of observatories that monitor our space surroundings. The goal of scientists is to timely detect the threat from space. The accuracy and power of astronomical instruments is growing all the time, and soon humanity will be fully able to control all the close approaches to the Earth. At the same time, it is so good that meteorites, and even alien spaceships, will have no chance of remaining unnoticed.
Fixing as many asteroids as possible is necessary not only to ensure the safety of the Earth, but also for the sake of scientific interest. After all, space debris is a unique material for research.
Everyone, of course, heard about the Tunguska meteorite - an air explosion that occurred in the area of the Podkamennaya Tunguska River on June 30, 1908. The explosion power corresponded to the energy of an average hydrogen bomb. Presumably then the icy nucleus of the comet exploded. 1989 - a kilometer-long rock made of dense basalt rocks flew only 690,000 kilometers from our planet: the distance by cosmic standards is negligible. 1994 - a twenty-meter asteroid exploded over the Pacific Ocean near Micronesia.
Approximately once a month, remaining completely unnoticed, a huge asteroid the size of a football field flies past our planet, and a collision with an asteroid several kilometers in diameter would be fatal for the Earth. A fireball flying at a speed of 800,000 km / h would destroy all life on our planet for tens, if not hundreds of thousands of years. Whole continents can go under water, and the sky is covered with impenetrable clouds of dust. According to the calculations of experts, given the current density of the world's population, in the event of an asteroid falling, for example, one kilometer in diameter will die every fourth inhabitant of the Earth. The cause of death will be earthquakes, fires, hurricanes, tsunamis (when an asteroid hits the sea), as well as hunger, which will be caused by climatic changes, the same as during the "nuclear winter". The catastrophe will have global consequences. The world economy will decline and civilization will be shaken to its very foundations.
Every year, clouds of cosmic dust and micrometeorites cross the Earth's orbit, and a real rain of stars falls on the Earth; astronomers have recorded thousands of "shooting stars". Meteorite storms of this kind do not represent a real threat to our planet, although they are capable of breaking through the roof of a car. But for satellites, a meteor shower can be fatal. An asteroid the size of a grain of sand has the penetrating power of a bullet fired from a large-bore rifle.
Found out that the destructive potential of stone meteorites is not as great as previously thought. In the air, they explode and crumble into small fragments. The affected area is getting larger, but the debris can no longer cause a tsunami and major destruction. Computer models of such a bombardment have shown that all stone meteorites with a diameter of up to 200 meters disintegrate, while iron meteorites behave as integral fragments.
In the whole "meteorite problem" today, the main difficulty is to predict the appearance of a cosmic meteorite threat with sufficient accuracy and time. Will astronomers be able to do this on the basis of observations with the help of their own, even the most modern instruments? Meanwhile, complex calculations show that the movement of small celestial bodies is very chaotic. As a rule, such chaotic wanderings between large planets end with asteroids falling onto Jupiter or the Sun, as well as their ejection outside the solar system. Under the influence of random disturbances, they are able to suddenly change their normal orbit to an extremely elongated one, approaching Mars and creating a potential danger to our planet.
Even solar wind and light can influence the movement of asteroids and comets. Individual parts of the asteroid facing the Sun are heated more strongly than others. This process leads to the fact that the trajectory of the asteroid changes slightly. And such changes are happening all the time. It is likely that sunlight is the reason why asteroids, planetoids and meteorites less than 20 km in diameter invariably move along trajectories that cross the Earth's orbit.
There is no stability in a huge swarm of meteorites. For billions of years, nothing has been able to keep them in the same orbits, therefore it is rather difficult to calculate their behavior. Almost all of them for us are objects with many unknowns: we cannot know the exact configuration of these blocks, their structure and composition, their thermal conductivity, their ability to absorb light, and finally, the speed and direction of their rotation. But, for example, the direction in which the comet rotates depends on where it starts to move - to Jupiter or the Earth.
A person needs to compile a catalog of all celestial bodies that pose a threat to the Earth, assess the likelihood of collision with them and determine whether it is possible to change the trajectory of an object so that it does not collide with our planet. At the beginning of the XXI century, astronomers have already discovered more than 3,000 small celestial bodies with a diameter of tens of meters to tens of kilometers, crossing the orbit of our planet, while more or less studied only a few hundred of them. The preliminary theoretical estimate of the total number of dangerous objects already exceeds a million!
For a decade and a half, minor planets that threaten our planet have been monitored, and an inventory of the heavenly messengers of the deadly threat has been carefully compiled. As part of research programs, it is planned to identify almost all asteroids with a diameter of more than a kilometer, approaching our planet at a critical distance of less than fifty million kilometers. Technical capabilities allow space guards to detect in the next ten years practically all asteroids with a diameter of more than 300 meters, crossing the planet's orbit.
A cardinal measure in the future will be the placement of a space observatory with a powerful telescope near the orbit of Venus. In this sector of the view of the solar system, the widest range of observation of asteroids, meteorites flying towards our planet opens. By the way, 5-6 intercontinental ballistic missiles with nuclear warheads would be enough to save the Earth from most dangerous meteorites. The likelihood that such measures will actually be taken sometime, scientists estimate as one in 20,000. For comparison: the probability of getting into a car accident is one in one hundred.
Scientists and designers will need many decades to create a reliable meteorite warning system. And just as much, if not more, time will be needed to build "asteroid fighters". In the meantime, not a single large meteorite has been discovered that could threaten our planet in the foreseeable future. But the statistics are relentless: sometime a collision should occur, which means that we need to continue observing near-Earth space. Ideally, we will be able to predict the likelihood of a cosmic apocalypse several decades before it. However, the main thing is not a prediction, but a defense.
Although, in itself, this kind of method of dealing with small planets is also very dangerous. After all, one cannot know for sure that all the debris after the explosion will go away from our planet - after an accurate hit on the target, the fragments of the smashed meteorite will be able to fly off to the Earth and wake up on it with hail. Falling them would probably do even more harm than hitting one block. A hail of debris will spill over vast areas of the planet, causing tremendous destruction. Therefore, experts are more inclined to think that shooting at a meteorite does not make much sense. It is necessary to make an aimed explosion not far from it. Then the asteroid can be thrown aside. It will go off course, but it will not fall apart. Or it is necessary to drill a celestial body and lay in it a charge that will change the course of the minor planet without destroying it.
However, shooting at celestial targets is still ahead. In the meantime, automatic probes are being created, which make it possible to selectively study asteroids and meteorites approaching our planet. For example, several research flights have already been carried out with hard landing of vehicles on meteorites and asteroids. The data on the change in the trajectories of the "celestial rocks" are now being processed, and in the future space experiments will make it possible to understand whether it is possible to force the asteroid to roll away from our planet …