On January 25, NASA reported that a potentially dangerous asteroid with a destructive power of "50 million Hiroshima" was flying towards Earth at great speed. There are only a few weeks left until the hot meeting. It's time to raise the long-sore, but more urgent than ever, question: what, in fact, are the chances of humanity to survive in opposition to an impartial space block?
Troubled past
The old woman-Earth has seen many difficult times in her lifetime. Her whole life is an endless confrontation. Approximately 4.5 billion years ago, when our newly-born parent was gaining planetary weight, she experienced countless collisions with the asteroids of the accretion disk. In an era when the Earth had not yet acquired the Moon, meteorites and planetesimals (less fortunate small protoplanets that did not manage to become independent worlds) rained on its hot lava-covered surface. The subsequent short period of respite resulted in a global cataclysm, reminders of which are visible every time we look up at the night star. In the period from 4.1 to 3.8 billionyears ago, the ice giants of the solar system Neptune and Uranus (in this order they were once located) under the influence of the combined gravity of Jupiter and Saturn changed places. Neptune was thrown out of the orbit of Uranus. These perturbations alarmed the Kuiper belt hive and the Oort clouds: the trans-Neptunian objects of the outer asteroid ring left their beaten orbits and rushed towards the Sun, towards the terrestrial planets. This period was called "late heavy bombing". Most of the craters of all solid objects in the system were formed at that time. How strong that meteorite attack was, says the flecked face of our satellite: the geologically dead Moon has retained all the scars. Even on Earth, which has repeatedly changed the relief and configuration of the continents,traces of polynomial impacts are noticeable (this is the scientific name for the collision of planets with celestial bodies, such as asteroids or comets). According to scientists' calculations, obtained by extrapolating data from lunar exploration, on the earth's crust of the Gade era (the first geological era that coincided with the "heavy bombardment"), there were more than 22,000 craters with a diameter of less than 20 km, about 40 craters over 1000 km in diameter and several meteorite bowls with a diameter about 5000 km. For comparison, the diameter of the Earth is 12,742 km.about 40 craters over 1000 km in diameter and several meteorite bowls with a diameter of about 5000 km. For comparison, the diameter of the Earth is 12,742 km.about 40 craters over 1000 km in diameter and several meteorite bowls with a diameter of about 5000 km. For comparison, the diameter of the Earth is 12,742 km.
Paradoxically, we owe life to the "late heavy bombardment". Most of the objects in the Oort cloud are cometary nuclei rich in methane, ethane, carbon monoxide, hydrogen cyanide and, of course, ice. They brought the basis of life to Earth - water and organic matter. They also set in motion the lithospheric plates and launched the heat exchange between the subsoil and the surface.
I gave birth to you, and I will kill you
What has become a blessing for the desert Earth, for living beings is comparable to Armageddon. According to paleontologists, in the past, asteroids have caused at least three waves of mass extinctions. 250 million years ago, a 60-kilometer meteorite that fell in the Wilkes Land area in Antarctica destroyed 96% of all marine and 73% of terrestrial species. The era of general death was called the great Permian extinction, the most massive of all. Neither before nor after it did the biosphere experience such severe shocks. Although the language will not turn out to be “light” shocks to call subsequent events. 50 million years later, the Earth suffered a new cataclysm - the Triassic-Jurassic extinction, which mowed down at least half of the species of that era known to science, including invertebrates that dominated the seas. There were also positive aspects in it:the mass death of some reptiles and the last giant amphibians has cleared an ecological niche for dinosaurs. But the age of the giants turned out to be short-lived: 65.5 million years ago they were destroyed by the fall of an asteroid, which left a reminder of itself in the form of the Chicxulub impact crater on the Yucatan Peninsula in Central America. The Cretaceous-Paleogene extinction made it possible for birds and mammals to settle. So today we, warm-blooded mammals, are the most evolutionarily advanced inhabitants of the planet. But judging by the frequency of mass extinctions in the past, our turn will soon come to sink into geological oblivion. How long is it left to wait for the arrival of the Doomsday space weapon and what are our chances of salvation?which has left a reminder of itself in the form of the Chicxulub impact crater on the Yucatan Peninsula in Central America. The Cretaceous-Paleogene extinction made it possible for birds and mammals to settle. So today we, warm-blooded mammals, are the most evolutionarily advanced inhabitants of the planet. But judging by the frequency of mass extinctions in the past, our turn will soon come to sink into geological oblivion. How long is it left to wait for the arrival of the Doomsday space weapon and what are our chances of salvation?which has left a reminder of itself in the form of the Chicxulub impact crater on the Yucatan Peninsula in Central America. The Cretaceous-Paleogene extinction made it possible for birds and mammals to settle. So today we, warm-blooded mammals, are the most evolutionarily advanced inhabitants of the planet. But judging by the frequency of mass extinctions in the past, our turn will soon come to sink into geological oblivion. How long is it left to wait for the arrival of the Doomsday space weapon and what are our chances of salvation?soon our turn will come to sink into geological oblivion. How long is it left to wait for the arrival of the Doomsday space weapon and what are our chances of salvation?soon our turn will come to sink into geological oblivion. How long is it left to wait for the arrival of the Doomsday space weapon and what are our chances of salvation?
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The scale of the tragedy
Space is a battlefield. And the first step in any war is to assess the forces and determine the location of the enemy. Let's do the same. In the solar system, the asteroid belts and the Oort cloud can be considered the main sources of the meteorite threat. The inner or "main" asteroid belt is located between Mars and Jupiter.
There are quite a few large bodies there: about 200 asteroids with a diameter of over 100 km, about 1000 with a diameter of over 15 km, and about 1.7 million objects with a diameter of over 1 km. Although most of these guys are on a short leash around Jupiter, they are still worth fearing. In general, we were very lucky with Jupiter: the colossal size and irresistible gravity of the gas giant repeatedly saved the inner planets from destruction. Suffice it to recall the impressive picture of the Shoemaker-Levy comet falling on Jupiter, which astronomers observed in 1994, or the accidentally noticed collision of 2009, which left a black scar the size of the Pacific Ocean on the face of the king of the planets. Since the "late heavy bombardment" Jupiter has taken almost all the blows, but even he is not omnipotent.
Much more concern is caused by the inhabitants of the Kuiper belt located beyond the orbit of Neptune (it resembles the Main Belt, only 20 times wider and 200 times more massive) and the Oort comet cloud surrounding the solar system in a spherical cocoon. It is home to short-period and long-period comets. The outer part of the Oort cloud is the approximate boundary of the solar system and can easily be impacted by nearby stars and the galactic core. It is extremely difficult to predict the behavior of outer asteroids and comets, not to mention the possibility of guests arriving from deep space. The exact size, composition, and structure of the cloud are still very poorly understood. According to astronomers' estimates, billions of objects have found shelter there, including really large ones, such as the hypothetical Planet 9 or Nemesis, the sun's companion star. Fortunately,the overwhelming majority of them do not pose a threat to us. They fly to themselves - and let them fly, as long as they don't touch us. What really attracts the attention of scientists is the 20,000 massive objects looming in the immediate vicinity of the Earth.
Of course, this is not a single flotilla. These are scattered objects of various groups, masses and sizes, whose trajectories, according to mathematical calculations, intersect with the orbit of our planet. Today, the list of potentially dangerous celestial bodies includes 74 space objects that threaten the Earth with a collision. Four of them will be used to converge in the coming decade: in 2024, the asteroid 1979 XB measuring 1.13 km, in 2027 - 9-kilometer 1990 MU and 100-meter 2019 MN2, and in 2029 - Apophis, who already managed to make a lot of noise., whose size is estimated at 325 m. If they pass by, their business will be continued by the 5-kilometer Phaethon and Tautatis, which will approach the minimum distance to Earth in 2050 and 2065, respectively.
Occasional strangers from distant areas are also dangerous. As practice has shown, they become noticeable only when it is too late to do something. A recent guest narrowly escaped meeting the Earth in the summer of 2019. On July 25, a 100-meter asteroid passed at a distance of only 70 thousand km from the Earth - 6 times closer to the Moon. He was accidentally noticed a few hours before the convergence of the Brazilian mission SONEAR. The real problem is that these objects are very difficult to detect. They are small and practically do not reflect light (cometary nuclei are completely covered with carbon and as black as soot). Telescopes are still able to see relatively large objects, but even small asteroids are dangerous. The famous Chelyabinsk meteorite, insidiously rushing from the direction of the Sun, was "only" 17-20 m in size (an insignificant speck of dust by cosmic standards), but even that was enough,to injure 2,000 people and damage 20,000 buildings. And yes, according to NASA experts, upon entering the atmosphere, the "speck of dust" exploded with a yield of 500 kilotons of TNT.
What we can?
The threat of an asteroid falling to Earth is not a reason to look for someone to blame. This is a reason to think about what to do. In April 2019, NASA director Jim Bridenstein said: an asteroid with a promising name for the Russian ear, 2019 PDC, is rushing to Earth at great speed. A collision is inevitable, and it will happen already in 2027, so the world needs to develop a planetary defense system as soon as possible. The news was immediately picked up by the media and happily carried to the people, like the banner of the end of the world. Fortunately, no 2019 PDC asteroid actually exists. Unlike the very real (happiness was short-lived) and having the same qualities of Apophis, 2019 PDC was invented to work out an action plan within the framework of the World Conference on Space Security, organized by NASA, the European Space Agency (ESA) and their partners. There is still a long way to the creation of a clear scenario of anti-asteroid defense, and, alas, we have nothing to oppose outside guests. Still, the world's leading experts shook the air for a reason. What have they come up with?
In short: it will hardly be possible to destroy, you need to try to knock the object off course.
First of all, it is necessary to develop a reconnaissance apparatus that could fly up to a potential threat, assess its size, composition and weak points. A project for such a device already exists - the DART probe invented by NASA. To embody DART in titanium and microcircuits, the brainchild of Elon Musk undertook the SpaceX company. The first tests are scheduled for June 2021, but judging by other projects Musk "on the dare", he will complete the task on time. The probe will become more than just a scout: its main purpose is to attempt to change the trajectory of the asteroid's flight with an aimed strike. Even if it does not work out, the kamikaze probe will transmit to the MCC all the necessary data for further actions. ESA plans to carry out a similar maneuver, only in the performance of the AIDA apparatus, in 2023. Officially, this is called a "non-nuclear kinetic ram". If it doesn't work out, a nuclear arsenal will be used.
The elimination of a dangerous asteroid with a nuclear warhead is the most adequate to today's realities, but not the safest way to protect humanity. A small miscalculation is enough - and not one large meteorite will fall on our heads, but shrapnel of radioactive fragments. Chelyabinsk residents are aware of what one small pebble is capable of. Therefore, scientists do not consider the destruction of an asteroid: a nuclear charge is needed to change the direction of movement of objects that cannot be taken with a ram.
Attaching a rocket motor to an asteroid to redirect it away from the planet is another ineffective, but has its place to be, solution. Asteroids rotate around their axis, and it is almost impossible to predict where the body will fly with additional acceleration. Not to mention the difficulty of installing motors that require the highest degree of synchronization.
Technologies that we do not yet have are considered as more promising solutions. For example, an electromagnetic catapult is a huge lunar "slingshot" that can shoot down asteroids by shelling stones from our natural satellite. Or an ion cannon working on the same target. Its advantage is that the compact unit can be placed on a controlled vehicle, which can, like a shepherd's shepherd, escort a lost space block away from Earth. Probably one of the most ambitious, but at the same time promising projects is a gravity tug. For its implementation, it will be necessary to place a sufficiently dense and heavy apparatus in the immediate vicinity of the object. Gradually, the interaction between the two bodies will change the trajectory of the asteroid. It will take years of worknot to mention the time to create such an apparatus. This is an extremely lengthy process.
Surely as technology advances, scientists will come up with new options. In the meantime, since it is customary to make a wish on a falling star: let it fall by!
Magazine: Secrets of the Universe №2 (147). Author: Aglaya Sobakina