- Natan Andreevich, on May 27, an asteroid with a diameter of 1.8 km flew past the Earth.

Its approach was warned in advance at

the CNEOS monitoring center at NASA

, scientists assigned it the status of potentially dangerous.

By what principles is the degree of danger of asteroids for the Earth determined?

Asteroids are small bodies in the solar system.

The largest of them are those whose dimensions reach several tens of kilometers in diameter.

We are most interested in near-Earth asteroids, 29 thousand of them have been discovered to date. They come in different sizes, among them there are also potentially dangerous ones that can collide with the Earth with unpleasant consequences for us.

Today there are 2.5 thousand of them.

At the same time, no such asteroids that pose a real threat in the foreseeable future have been identified so far.

- What are the approximate timeframes?

— The next hundred years.

The fact is that we can make relatively accurate predictions for a century ahead.

With the increase in time, the error of forecasts increases; it is useless to try to predict something for a period of more than a century.

So this does not mean at all that dangerous asteroids do not exist - we just have not found any yet.

And the total number of near-Earth asteroids is estimated at about 100 thousand. Therefore, the main task is to search for and track as many asteroids as possible.

  • Earth

  • Gettyimages.ru

  • © Bernt Ove Moss / EyeEm

There are special organizations for this, including monitoring centers at NASA.

So far, no dangerous asteroids have been found, but one asteroid has been identified, which in theory could pose a threat in the future, although not within the next hundred years.

This is Apophis, it was discovered in 2004.

Then scientists calculated that the asteroid will crash into the Earth with a probability of 3% - this is a lot.

Apophis has a diameter of 350 meters and a mass of 50 million tons.

That is, it is larger than the Tunguska meteorite, its fall will cause a catastrophe not of a local, but of a continental scale.

This forecast then greatly alarmed everyone, the governments of a number of countries allocated funds to track such asteroids.

Subsequently, scientists refined the trajectory of Apophis.

It is now known that it should not collide with the Earth, but will fly very close to it in 2029 - at a distance of about 32 thousand km from the planet's surface.

This is even closer than the orbit of geosynchronous satellites, so an asteroid could, in principle, bring down one of them.

Once again, it will return to Earth in 2036 and fly by already at a distance of 36 thousand km.

We can be sure of the accuracy of these forecasts, since a lot of attention was riveted to Apophis, many observatories participated in estimating the trajectory of its movement.

So in this case, the error will be no more than a hundred meters.

— Are there any other potentially dangerous asteroids?

The most famous asteroid is Bennu.

The probability of its collision with the Earth is small, about a tenth of a percent, but still it is not zero.

And it is larger than Apophis - its diameter is about a kilometer.

The Americans even sent a device to him, which landed on the surface and took soil samples, now it is flying back.

Presumably, this device will return to Earth next year.

Asteroid Bennu will approach our planet later than Apophis.

I think that by that time some means of counteracting such asteroids will already be put into operation, capable of changing the trajectory of their movement.

  • Photo of asteroid (101955) Bennu taken by the OSIRIS-REx probe on December 2, 2018 from a distance of 24 km

  • © NASA / Goddard / University of Arizona

- Can the trajectory of an asteroid suddenly change under the influence of some external factors?

- No, the only risk in this case is the risk of making a mistake in the calculations.

However, in general, now forecasts are made very accurate.

The calculation takes into account the gravitational influence on the asteroid of all the planets of the solar system, other asteroids, and even the influence of solar radiation, although in the latter case the influence is so weak that it does not exceed the error.

I must say that it is much easier to calculate the trajectory of an asteroid than a comet.

Comets can also pose a danger to the Earth, especially considering that the nuclei of comets are sometimes made of iron.

The difficulty is that the comet is most often a block of dirty ice.

Water evaporates, and during evaporation, a reactive force arises, which is very difficult to calculate and predict.

Therefore, in the case of comets, forecasts are only possible for several years ahead.

Fortunately, there are few comets among near-Earth small cosmic bodies, less than 10% of the total.

However, there are also very big difficulties and gaps with the identification of asteroids.

This was clearly shown to us by the example of the Chelyabinsk (Chebarkul) meteorite.

If an asteroid flies up to the Earth from the side of the Sun, it is almost impossible to notice it against the background of a bright sky - this happened in the case of the Chelyabinsk meteorite.

In order to detect such an asteroid in time, it is necessary to use special detection methods.

For example, to track such bodies, spacecraft should be launched that can observe from a different, non-terrestrial angle.

This method is used, it has already proven its effectiveness - so many new asteroids have been discovered.

I note that the American Kepler space telescope played a special role in the discovery of asteroids.

With its help, not only about half of the currently known exoplanets were discovered, but also a significant proportion of asteroids.

— What technologies for deflecting asteroids are currently being developed in Russia and other countries?

- Everyone is talking about the idea of ​​destroying an asteroid using nuclear charges, such a scenario was even shown in a feature film.

However, in a real, and not cinematic, scientific environment, this idea is highly skeptical.

In this case, you will have to launch a certain apparatus with a nuclear bomb into space, and if something does not go according to plan, it may fall to Earth.

Therefore, this method is considered very risky and will be considered only as a last resort.

As for the idea of ​​deflecting an asteroid by colliding a spacecraft without a nuclear charge with it, this is a problem that can hardly be solved.

For example, the mass of Apophis is about 50 million tons.

And we can send into space a ship weighing only five to seven tons, so far the technologies created by mankind are at this level.

It is clear that for an asteroid of this size, the terrestrial apparatus will have no greater impact,

  • Fragment of the Chelyabinsk meteorite

  • RIA News

  • © Valery Melnikov

Therefore, other methods are now proposed.

For example, a method that can be conditionally called "space billiards": it is planned to use not a spacecraft, but another smaller asteroid to change the orbit of a dangerous asteroid.

This idea is now being worked out and the calculations show what should happen.

And we can already influence the orbit of a small asteroid with the help of a spacecraft.

Last fall, NASA sent a device of this kind into space.

- We are talking about the DART device, which must hit the asteroid in order to change its orbit?

- Yes, for now the task is simply to study how such interaction will occur.

These are the first practical steps in this direction, apart from modeling by computation.

Directing a small asteroid to a large one is also very difficult, because even a small object has a mass of several thousand tons.

However, this problem can be solved by using a gravitational maneuver.

The bottom line is that this asteroid will be at a distance of several hundred thousand kilometers from Earth, not very far in space terms.

And if you correct its trajectory in time, the Earth's gravitational field will accelerate its movement towards the dangerous asteroid.

And initially, you can give it the desired direction with the help of a spacecraft - for this task, its impact is enough.

Modeling shows that it is quite possible to perform such an operation, this is a realistic task.

However, there are difficulties here too: it is very important to point the device correctly, not to miss.

Otherwise, the mission will fail.

Therefore, we need to develop this technology in practice, I am sure that this will be done.

In this case, there is another problem: in order to have time to deflect a dangerous asteroid when it appears in our field of vision, it is important that the small asteroid is already on “duty”, we must have such an object at hand by that time.

To do this, a small asteroid should be transferred to a duty orbit in advance so that it approaches the Earth every year, falling into its gravitational field.

Having fixed a special spacecraft on such an asteroid, we will be able to control its trajectory.

  • Gettyimages.ru

  • © Matthias Kulka

— And what other ideas find practical implementation?

- Approximately 20 years ago, the Americans created a project called Deep Impact.

Then the comet Tempel 1 became the target of the spacecraft. The device did not collide with the comet, but dropped a special impact module weighing 400 kg on it, flying next to it.

The collision led to the evaporation of the substance that makes up the comet, which allowed scientists to determine its composition by spectrometry.

The mission was a success, it was a great success.

In addition, in the 2000s, when it was still believed that the asteroid Apophis would collide with the Earth, our Lavochkin NPO created a project to send a special apparatus to it in order to clarify its trajectory.

The fact is that it is the observations made in the immediate vicinity of the object that are the most accurate.

But while the device was being developed, it was already mathematically established that Apophis should not collide with the Earth, and the project was curtailed.

Although, if it were brought to the end, very interesting data could be obtained.

— Scientists say that the asteroid threat is absolutely real, but at the same time, so far all projects aimed at combating it have either been curtailed or not completed.

Maybe humanity, world governments underestimate the danger?

And are the efforts that are being made today to prevent it enough?

— I think that's not enough.

Moreover, such work does not require huge expenses, so it cannot be said that the issue rests on finances.

There are no technical obstacles for this either - we are talking about the use of technologies already known to us.

At the same time, it is obvious that it is necessary to prepare for the asteroid threat in advance, otherwise it may simply be too late.

— Can any one country implement such a project, or is international cooperation needed?

— To a certain extent, such cooperation exists.

For example, the UN has a special department for the peaceful use of outer space.

And within the framework of this department, experts from different countries gather once or twice a year to discuss various problems, including the asteroid threat.

From Russia, for example, specialists in nuclear charges are participating there, because so far no one has completely written off the idea of ​​using a nuclear explosion to destroy an asteroid.

Of course, the cooperation of countries is very important.

For example, to accurately calculate the trajectories of asteroids, the more observation stations involved, the more accurate the data.

And this will allow us to detect danger earlier, to start preparing earlier.

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