Will the Earth collide with the approaching asteroid Apophis

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Will the Earth collide with the approaching asteroid Apophis
Will the Earth collide with the approaching asteroid Apophis
Anonim

Today, the asteroid Apophis will approach Earth at its closest distance in eight years. This will allow scientists to refine the parameters of its orbit and, probably, understand what it is made of. Such data are necessary in order to refute or confirm the likelihood of a collision with the Earth in 2029 and 2068. The fall of Apophis on our planet threatens with catastrophic consequences.

We all walk under Apophis

In 2004, employees of the Kitt Peak National Observatory, located in the Sonoran Desert (Arizona, USA), noticed an unknown asteroid in relative proximity to Earth. Bad weather and technical problems made it difficult to get a good look at the find. However, it was clear that this is a rather large celestial body - about 400 meters in diameter.

A few months later, the asteroid was examined by specialists from the Siding Spring Observatory (Australia). They confirmed the information of their American colleagues and clarified the parameters of the orbit. By December, after analyzing the data, experts from the NASA Center for the Study of Near-Earth Objects calculated: the probability of a collision with the Earth is about two percent, and the estimated date of the disaster is April 13, 2029. Asteroid 2004 MN4 (later named Apophis in honor of the ancient Egyptian god of darkness and evil) is the first astronomical object in the history of observations, which was assigned four points on the Turin scale of danger of celestial bodies.

"Apophis is famous for causing panic in 2004. When the parameters of its motion were determined using optical telescopes, it turned out that it can get to Earth with a probability of 1.5-2 percent. This is a lot, given its size - about 350 meters across. This means that the mass is about 70-80 million tons. In the event of a collision, the consequences would be monstrous. Therefore, financial resources were allocated to clarify the parameters of its orbit and the expected time of the catastrophe, if it really happened. This made it possible to create a whole network for tracking of such asteroids ", - explained Nathan Eismont, a leading researcher of the Department of Space Dynamics and Mathematical Information Processing of the Institute for Space Studies of the Russian Academy of Sciences, Doctor of Physical and Mathematical Sciences.

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The expected position of Apophis relative to the Earth on April 13, 2029

Thanks to the tracking network, scientists detect potentially dangerous objects almost every week. Their orbits intersect the orbit of our planet, and therefore there is, albeit a tiny, possibility of collision. Since the discovery of Apophis, about 20 thousand of such celestial bodies - asteroids and comets - have been identified. However, Apophis is still considered one of the most serious threats.

Delayed disaster

In 2009, employees of the Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences and the Lavochkin Scientific and Production Association calculated that the Earth could collide with Apophis in the spring of 2036. And although the likelihood of such an outcome is small, the explosion will be almost a thousand megatons in TNT equivalent. For comparison: the Tunguska meteorite exploded by only ten megatons, and the power of the strongest hydrogen bomb ever tested on Earth was 50 megatons.

The authors of the work did not predict a global catastrophe after the fall of Apophis, but a territory approximately equal to France, in their opinion, would turn into a desert. True, the scientists specified, these conclusions should be revised after the asteroid approached the Earth in 2013 and 2021.

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Photos of Apophis taken by NASA telescopes from October 31 to November 13, 2012

Four years later, this is what happened. Comparing the data of astronomical observations in 2011, 2012 and 2013, researchers from NASA estimated the chances of our planet colliding with Apophis in 2036 as one in a million.

Nevertheless, in many countries, including Russia, experts were looking for ways to better study the asteroid and understand how to prevent a possible catastrophe. For example, Vladimir Popovkin, the then head of Roscosmos, announced plans to track the trajectory of Apophis by installing a radio beacon on it using a spacecraft, which was supposed to land on the asteroid around 2020.

"It was a joint project of IKI RAS and NPO Lavochkin (part of Roskosmos - Ed.). We wanted to bring the spacecraft into the vicinity of Apophis and make a satellite out of it. This would help to examine the asteroid properly, determine its mass, and clarify the orbit and understand that this is a heap of rubble, stone or iron. Its composition has not yet been studied. But, unfortunately, the project has remained on paper, although it has already been determined which device will fly, how much it will cost, which rocket - the carrier will be required. Probably, the fact that Apophis was still recognized as relatively safe played a role, "said Nathan Eismont.

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The flight path of the asteroid Apophis

Reduced accuracy

However, in 2019, American astronomers, observing Apophis using the Subaru ground-based telescope, found out that its orbit could change. It is influenced by the so-called YORP effect (Yarkovsky - O'Keefe - Radzievsky - Paddeck effect), which leads to an increase in the speed of rotation of the body. As a result, the asteroid is displaced from its own trajectory, determined only by the gravitational field, by about 170 meters per year. This means that the scenario of a catastrophic collision with the Earth cannot be completely ruled out. The time of a possible apocalypse was designated April 2068.

"The Yarkovsky effect is a phenomenon that cannot be easily understood. Sunlight consists of photons. They heat up the surface of asteroids, and they get the opportunity to re-emit heating. When predicting the motion of celestial bodies, this must be taken into account. However, in the case of Apophis, the correction for the Yarkovsky effect reduces the accuracy of calculations. After all, in order to correctly evaluate everything, you need to know the properties of the surface: what kind of rock, how it heats up, how it cools down. And nobody knows this yet, "says Professor Eismont.

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Apophis's position relative to Earth on March 5, 2021

The chance to find answers came on March 5, 2021, when Apophis came closest to Earth in eight years. Right now, NASA's NEOWISE infrared telescope is pointed at the asteroid. Its main task is to calculate the parameters of the motion of a celestial object and obtain the most accurate images of its surface.

Once again, such an opportunity will appear on April 13, 2029. On this day, Apophis will pass at the minimum distance from the planet's surface - about 29,470 kilometers, will be inside the orbits of geostationary satellites, and it will be possible to distinguish it with the naked eye. However, even in this case, the probability of collision with the Earth is negligible. According to Nathan Eismont, less than a thousandth of a percent.

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