On September 15, 2013, a18 meters long and weighing about 11,000 tons, it crossed the Russian sky before disintegrating at an altitude of 23 kilometers above the city of Chelyabinsk in the south of the country. The very powerful shock wave caused a lot of damage, causing the And buildings in the region. L’ released during this explosion was actually estimated at 30 times the power of the Hiroshima bomb. It is therefore the largest known event of this type since the fall of the object above (Siberia) in 1908, including the explosion in it had razed a forest within a radius of 20 kilometers.
In both cases, the disintegration of the meteorite at high altitude avoided a collision with the earth’s surface that would surely have led to a far more dramatic catastrophe, reminding humanity that we are continually exposed to this type of risk for the environment at the moment unpredictable.
A large plume of meteoric dust
The entry into the atmosphere of the so-called Chelyabinsk meteorite, and in particular its explosion, was extensively documented by numerous amateur videos, which allowed scientists to reconstruct the meteorite’s trajectory and define its characteristics.
, nothing better than finding fragments. But this is not so obvious. When a meteorite enters Earth’s atmosphere, the warming it experiences usually leaves a small amount of dust behind. The meteorite usually ends up “burning up” almost completely before hitting the ground. It is often very difficult to find this very fine dust sprinkled on the landscape of a large area.
However, in the case of the Chelyabinsk meteorite, the relatively large size of theproduced a large plume of dust that remained suspended in the atmosphere for several days, allowing for easier collection of these tiny particles. In the following months, much larger fragments were also discovered. he was thus raised from the bottom of Lake Chebarkul. The analysis of these residues showed that it was a (rocky meteorite).
Strange and exotic graphite crystals
But it was by analyzing the tiny specks of dust that Russian scientists made a fortuitous and surprising discovery. Under’from a was actually observed. Very small in size, few only, these crystals come in two distinct forms hitherto unknown on Earth: some have an almost spherical shape and others have the shape of a hexagonal rod. X-ray analysis reveals that they are actually crystals of graphite, one of the crystalline forms of the same that is still commonly used in our pencils.
But these crystals have an additional feature. They contain at the center a carbon nanostructure that could be a buckminsterfullerene, a spherical molecule composed of 60 carbon atoms and which has the shape of afootball (hence the nickname of footballer). This nanostructure could also be polyhexacyclooctadecane, a molecule composed of carbon and .
A specificity of the Chelyabinsk meteorite?
The very exotic architecture of these crystals suggests that they formed under high temperature and high conditions, which could correspond to the moment of fragmentation of the meteorite in the earth’s atmosphere. However, the exact mechanism of their formation remains to be elucidated. These results were published in the journal .
The next step is now to find out whether these crystals are specific to the Chelyabinsk meteorite or not by looking for their traces in the dust samples of other meteorites.