Maxim Russo: Heavenly Guests

Maxim Russo Vladimir Surdin Natasha Chetverikova/Polit.ru

On January 15, the first public lecture by Polit.ru was held in the I. S. Turgenev library named after I. S. Turgenev. It was read by a longtime participant in our project by the famous astronomer and a popularizer of science, senior researcher at the Sternberg State Astronomical Institute Vladimir Georgievich Surdin. The theme of the lecture is “Meteorites - heavenly guests: desired or uninvited?”

In the lecture, Vladimir Surdin reminded the students of the students about the small bodies of the solar system, and also spoke about recent events and research related to meteors and meteorites. In the XXI century, when photographic equipment became very common, people are increasingly managing to take photos or even a video of the moment of fall. The first meteorite, which was shot at once with several cameras, was the meteorite that fell on October 9, 1992 in Pickskiil, not far from New York. He flew in the sky on Friday evening, when a football match of school teams was in the local stadium. Some spectators managed to raise video cameras and remove the meteorite. 16 videos are known. Photos and videos are interesting because in some cases scientists manage to calculate the meteorite orbit with their help. So far, they managed to do this for ten meteorites. It turned out that these meteorites were immigrants from the asteroid belt located between the orbit of Mars and Jupiter.

For some meteorites, a source in the asteroid belt is known - this is a large asteroid Vesta. This was done not by calculating their trajectory, but by analyzing the composition of meteorites. Pictures of Vesta, which in 201 - 2012 took the Dawn spacecraft show that she clearly experienced serious clashes, as a result of which she lost part of her substance. A huge crater is located near the South Asteroid pole with a diameter of up to 460 kilometers (the diameter of the total Vesta is about 530 kilometers). There are other craters on the surface of an asteroid. The destruction of part of the Vesta originated the whole class of smaller asteroids. And some fragments over time reached the Earth, becoming meteorites. They were called Hed Meteorites , as in their characteristics they break up into three classes: chorades, eucritis and diogenites. So thanks to meteorites, scientists got the opportunity to explore the breed samples from an asteroid, although space equipment still cannot deliver such samples to Earth. At the moment, more than three hundred HED-meteorites are known.

One of the meteorites that once formerly part of Vesta

But not only samples from the asteroid Vesta fall into the hands of scientists thanks to meteorites. Meteorites of lunar and Martian origin are now known. There are a lot of lunar meteorites, Martian-approximately 45-50, not for all of them Martian origin is finally confirmed. The most famous meteorite from Mars is called Alh 84001 (Allan Hills 84001). Its weight is 1.93 kilograms, and it was found in 1984 in Antarctica. Thanks to the voids found in this meteorite, its origin was proved. Scientists analyzed the isotopic composition of gases that fell into these voids when the rock from which this meteorite consists was only formed. And this composition coincided with the data on the atmosphere of Mars, which were obtained by the Curiosity Markout.

ALH 84001 meteorite

But not only these were famous for the ALH 84001 meteorite. In 1996, an article was published in Science magazine, which stated that when studying this meteorite under an electron microscope, structures of 20-100 nanometers were found, which, according to the authors of the article, were petrified bacteria. Therefore, at least once, bacteria existed on Mars.

Structures found in the alh 84001 meteorite

Now similar formations have been found in some other meteorites. Scientists have not yet come to a consensus on their nature: whether they represent really petrified microorganisms or are they structures of non -biological origin.

The origin of the Kaidun meteorite is interesting. He fell on December 3, 1980 on the territory of the Soviet military base in Yemen. From there he was brought to the USSR to the Academy of Sciences. The Kaidun meteorite has a rather unusual composition for meteorites. Now it is assumed that once he was part of Fobos-one of the satellites of Mars.

Many are concerned about the question of the potential danger of meteorites. In fact, judging by the fact that about two hundred large meteorite craters were found on Earth, in past eras large meteorites fell to Earth. The size of the meteorite is correlated with the diameter of the crater as 1 to 20, that is, the celestial body with a diameter of 100 meters will leave a crater of 2 kilometers in size. The famous “Chelyabinsk meteorite”, which arrived on February 15, 2013, according to calculations, at the time of entering the atmosphere was about 17 meters and weighing about 10 thousand tons. Its trajectory was gentle, so he made a long way in the atmosphere, destroying the interaction of the air, and, in the end, broke up into small fragments. If he fell more steeply, he would bring much greater destruction.

Since the 2000s, automatic telescopes have appeared that photograph the sky and independently compare sequentially taken photos. If it moves to any object against the background of stars, then this is an asteroid, comet or meteoroid. Then you can calculate its trajectory and find out if he will collide with the ground. Thanks to the appearance of these telescopes, the number of an asteroids opened annually has increased significantly and is measured in thousands.

There were two cases when astronomers managed to fix the moving heavenly body in the vicinity of the Earth, which became a meteorite, and predict its trajectory in advance. On October 6, 2008, the Mount-Lemmon (USA) observatory was discovered by the TC3 asteroid. Its diameter was 2-5 meters. He entered the earthly atmosphere on October 7, 2008 and exploded above the ground in the north of Sudan, about 100 kilometers south of the border with Egypt. During the searches in the desert, it was possible to find his fragments.

One of the fragments of asteroid 2008 TC3

The second case occurred in 2014. Asteroid 2014 AA was seen on January 1, and hit the earthly atmosphere the next day. Meteorites that were his fragments could not be found, since he fell over the Atlantic Ocean. Its diameter was 2-4 meters.

But 2008 TC3 and 2014 AA - small asteroids, which were almost completely destroyed during flight in the atmosphere. There are much more serious objects. In 2004, an asteroid was opened, which later received the name Apophis . Its size is now estimated at 325 meters. Observations of its trajectories show that in 2029 it will come closer to the ground, but will not encounter it, but at the next rapprochement, in 2036, there is a probability of a collision, although it is quite small (it is estimated as 1 to 250,000).

Possible places for the fall of the aphyr in the event of a hypothetical collision with the ground in 2036.

When apofis falls on land, the effect will be like an explosion of a powerful bomb and local destruction will occur. But in the event of a fall into the ocean, he will cause a very powerful tsunami, from which millions of residents of coastal countries will suffer. However, it should be remembered that the probability of the fall of the aphyul to Earth and in 2036 is extremely small.

See also: in Antarctica, scientists have found a trace of a fallen meteorite in the Martian meteorite found an object like a large iron meteorite found on the surface of Mars Chelyabinsk meteorite fell to the ground after a collision with another body 10 million years ago