Earth - Apophis: dangerous convergence
Astronomers around the world do not stop their observations of the flight of Apophis, an asteroid, which after some time will approach a very small distance to the Earth.
A few years ago, the message about this rapprochement very excited the public, but at the present time people practically don’t remember it. But experts remember well.
For the first time, a dangerous asteroid was discovered by American astronomers from the Keith Peak National Observatory, which is located in Arizona. Its very name speaks for itself, because the asteroid was named Apophis, and this is how the ancient Greek god of destruction and darkness was called. This god was depicted in the form of a huge destroyer snake that lived in the underworld and from there tried to destroy the Sun, while it makes a night transition. It should be noted that the choice of such a name for an asteroid is quite justified and traditional, because from the very beginning all celestial bodies were called by the names of the ancient gods, and only then they only began to call the names of those who actually existed historical characters.
Scientists have found that the asteroid once every seven years crosses the near-Earth orbit, and with each new “visit” it increasingly reduces the distance to the planet. According to experts, Apophis will approach a little more than 35 thousands of kilometers in April 2029 of the year, and it can collide with the Earth in 2036.
A little earlier, at the beginning of 2011, at one of the scientific conferences held in Moscow, Leonid Sokolov, an employee of St. Petersburg State University, even named the most probable date of the collision, namely 13, April 2036, was named. At the same time, scientists have not been able to determine exactly where the point of impact will be. Still, there are certain assumptions put forward by Boris Shustov, Director of the Institute of Astronomy of the Russian Academy of Sciences. According to him, the asteroid can collide with the Earth in the zone from the Urals, along the border of Russia, Mongolia and Kazakhstan, through the waters of the Pacific Ocean, Central American territories, waters of the Atlantic and to the African coast. In addition, it is not so easy to accurately predict the asteroid's orbit. The fact is that there is a Yarkovsky effect, the essence of which lies in the existence of a small but effective force. It manifests itself in the fact that on the one hand an asteroid emits more heat than on the other. When the asteroid turns away from the Sun, it begins to radiate heat accumulated in the upper layers. Thus, a small reactive force appears, which acts in the opposite direction to the heat flow. Scientists do not even suggest exactly how this effect can affect the trajectory of Apophis, about which virtually nothing is known - neither the speed of rotation nor the direction of the axis along which it rotates. But these parameters are necessary for determining the Yarkovsky effect.
But Russian scientists are rushing to reassure the public, declaring that the probability of hitting is very small, it is approximately 1 to 100 thousands. The reason for such confidence of scientists in the relative safety of Apophis for the Earth lies in the fact that they were able to more accurately determine its orbit. At the same time, scientists do not exclude the fact that even if there is no collision in the 2036 year, this may well happen in subsequent years. At the same time, Russian astronomers rely on the results of NASA research, according to which in this century about 11 collisions with the planet are expected, and 4 from these collisions may occur before the 2050 year.
If, however, the collision of Apophis and the Earth occurs, mankind is in mortal danger. Despite the fact that an asteroid itself is small (its diameter is about 270-320 meters), an object with a mass of several tens of millions of tons hit the surface of the planet at high speed (about 50 thousands of kilometers per hour) with an will be equal to 506 megatons. Thus, in the case of "contact", the energy of the explosion can be compared with the detonation of the entire nuclear weaponsthat exists on the planet. Damaging factors will be similar to the effects of a nuclear weapon explosion, except that there will be no radiation.
At the same time, Russian scientists claim that according to the study, the probability of death from a collision with an asteroid is approximately 1 to 200 thousands.
It should be noted that today under the scrutiny of domestic and American scientists are more 830 potentially dangerous asteroids, and among them there are larger in size than Apophis. Therefore, a collision with any of them can completely destroy the planet. According to Boris Shustov, the most dangerous is the recently discovered asteroid, which the planet may encounter in eight hundred years. “I am glad” only that celestial objects of similar sizes appear within the Earth once every tens of millions of years.
Currently, according to scientists, there are about 7 thousands of celestial objects that converge with the planet Earth, of which about one-seventh are potentially dangerous. At the same time, American astronomers say that after 2029, humanity will have enough time to slightly move Apophis from its orbit in such a way that it does not fall into the so-called "gravity well", that is, the field that is located on the approaches to the planet and which the asteroid can send directly to it. Therefore, several methods have been proposed for shifting a celestial object from its shaved, in particular: a powerful frontal impact, changing the orbit with the help of a rocket engine used as a “tractor”. In addition, you can try to change the trajectory of the asteroid by exploding a nuclear charge on its surface.
According to a leading researcher at the Institute of Astronomy of the Russian Academy of Sciences, Doctor of Physics and Mathematics Alexander Bagrov, today mankind has created more than 40 different tools to deal with various celestial objects that are dangerous to the planet. The most discussed are the two options - the Russian, which involves placing a radio beacon on an asteroid, and the US, which involves a nuclear attack by Apophis in the event of its critical approach to the Earth.
In addition, there are other equally interesting developments. Thus, in particular, the European Union plans to allocate about 4 million euros for a three-year project called NEO-Shield. The project will bring together scientists from six states who should develop various ways to protect against potentially dangerous celestial objects. A certain amount of funds (about 1,8 million euros) will be allocated by European research institutes and enterprises associated with the aerospace industry. By the way, it was these structures that actively supported the initiative of the European Union, because earlier he had not allocated money for such studies. By the time the funding coincided with a cutback in the US state budget for the space industry. Thus, from the point of view of theoretical developments, Europeans can feel pride about the fact that it was they who had the honorable mission of saving the planet. But at the same time, this project does not imply the practical implementation of the developed strategies.
According to representatives of the aerospace European company Astrium, the construction of a real shield against asteroids will require significant investments (about 300 million euros), and the Europeans do not have such an amount. By the way, it was precisely because of the lack of money that the Don Quixote project was not brought to its logical conclusion, the essence of which was to send a companion ram to Hidalgo (another dangerous asteroid) to change the trajectory of the latter.
Russian astronomers are also not lagging behind, but their research on the detection of potentially dangerous celestial objects is carried out only within the framework of scientific research institutes. So, in one of the Russian research institutes, the Makeev missile center, at this time, the development of two spacecraft designed to fight asteroids is underway. One of them, Kaissa, is designed to perform reconnaissance functions, in particular, to assess the chemical composition, structure, and trajectory of asteroids. The other, the “Trap,” is a percussion apparatus carrying a number of nuclear warheads. We will remind, earlier from the scientists of the center there were proposals to destroy all potentially dangerous objects with nuclear weapons. At the same time, delivery of warheads shall be carried out with the help of the Soyuz-2 and Rus-M launch vehicles.
But still, America currently holds the first positions in the study of potentially dangerous celestial bodies. In the United States there are several of the largest centers that identify small planets and space threats. Thus, they get 99 percent of all information on the subject.
At the same time, American scientists are trying to block access to other states to their research data. So, for example, in the 2000 year, they banned Russian scientists from using the results of their observations of the geostationary orbit, and later 9 years - and data on observations of the entry of fireballs into the earth’s atmosphere. In such conditions, Russia simply has to create its own program for monitoring potentially dangerous objects and seek cooperation with other states. In addition, Roscosmos fears that, due to the alleged collision of Earth and Apophis, a new arms race may begin in the world, the end result of which will be the creation of the latest means of armed confrontation not only on the planet, but also in near-earth orbit.
If we talk about American developments in this area, then you can not ignore the project, unique in its essence - Hypervelocity Asteroid Intercept Vehicle (HAIV). Its essence is to create a nuclear interceptor of asteroids. By and large, we can say that this program developed by NASA is aimed at creating technologies to protect the planet from the possible consequences of an asteroid impact. HAIV itself is a spacecraft, which with the help of kinetic energy can penetrate into the asteroid, and then a nuclear bomb should fire. Thus, either the complete destruction of the celestial object will occur, or it will be possible to move it from the trajectory. At the same time, debris will not be dangerous to the Earth. This technology is expected to become most effective in the fight against asteroids - less than ten years before the collision, the device will be able to respond to the threat.
It will directly intercept the celestial body following the example of the EKV interceptor of the US missile defense system. Homing technologies with the use of optical systems and guidance in the first parts of the trajectory have been developed to a sufficient degree, however, there are certain problems. So, for example, if we take into account that the velocity of the collision of an apparatus with an asteroid will be approximately 10-30 kilometers per second, then the apparatus will not have enough kinetic energy to destroy the asteroid. The fact is that modern technologies have not yet reached the level of development at which a nuclear device could be undermined at high speed, since the impact of the components of this device will be completely destroyed and there will simply be no explosion.
That is why the project developers have designed a special bow, which will be separated and which should pierce a hole in the asteroid, roughly speaking, a hole so that an interceptor with a nuclear bomb can safely enter the depths of the asteroid. If the calculations of NASA experts are justified, then a nuclear explosion will have a power of about 6 megatons.
The project of the company from the United States SEI is also of some interest. Its essence is to launch small robots. They must burrow into the surface of the object, throw the rock into space and thus change the trajectory of its movement.
Another American nonprofit structure - the B612 Foundation, which included scientists and former NASA astronauts, offers to launch an infrared telescope into space for 2017-2018, which will search and track potentially dangerous asteroids. The name of the organization is borrowed from literature, from the story of A. de Saint-Exupery “The Little Prince”. Everyone who is part of it is convinced that American astronomers do not pay enough attention to small asteroids, preferring to study large objects whose diameter is at least one kilometer. Their telescope, on the contrary, is designed to track small celestial objects. The Sentinel telescope will be in a near-earth orbit of about 5,5 years at a distance of 50-270 millions of kilometers from the planet. Thus, it is assumed that for the entire period of its stay in space, the telescope should find about 90 percent of all small asteroids, whose diameter is more than 150 meters. To implement the project requires several hundred million dollars.
There are international developments. So, quite recently the technology of “painting” celestial objects was developed, which is designed to protect the planet from a potential threat. Scientists from the University of Texas, together with the Ames Research Center (NASA) and the research center of Saudi Arabian ruler Abdel Aziz, have contributed to the development of anti-asteroid technology. They proposed to change the trajectory of the asteroids without using nuclear weapons. The essence of their technology is to influence the motion of a celestial object by changing its reflectivity. To do this, using a special unmanned spacecraft, apply paint (either light or dark) to the surface of the asteroid. At the same time, the Yarkovsky effect will actively take effect. Since the reactive force that occurs under its influence is very small, it can be significantly increased with the help of contrasting colors. Scientists want to try their method on Apophis. At the very beginning of the mission, called Apophis Mitigation Technology Mission (AMTM), it is supposed to send a small-sized reconnaissance aircraft to determine the parameters of the asteroid. Then a spacecraft equipped with an electrostatic painting unit, which will cover some parts of Apophis with paint, should go to it. According to scientists, this will give the opportunity to change the asteroid albedo and reject its trajectory by about three degrees.
Materials used:
http://nvo.ng.ru/printed/273107
http://galspace.spb.ru/index129.html
http://stp.cosmos.ru/index.php?id=1304&tx_ttnews%5Btt_news%5D=581&cHash=59aae60531287d16da6641bf2e7259ba
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