Modeling of protection from asteroids has docked with the experiment

Physicists have revealed the most realistic model of the impact of the destruction of the asteroid. For this, they went through many possible options and compared them with the real experiment, simulated the shooting down of a meteorite. The results showed that modern science can fairly accurately simulate such events. Article published in the journal Earth and Space Science.

The fall to Earth of a large asteroid — the event is extremely unlikely. However, despite the vanishingly small chance, the damage can be huge. So, the famous Tunguska explosion was equivalent to a hydrogen bomb, and only by a lucky chance he fell away from the settlements. For the development of possible future protection from such threats the research is conducted. So, NASA is planning a mission DART is an attempt to deflect the asteroid rammed his probe. But, in order for these experiments to be meaningful, you must be able to accurately calculate such impacts.

Thane Remington (Remington Tane) from the Lawrence Livermore national laboratory and her colleagues decided to test which of the modern models of deformation of a solid body is best suited to calculate a collision with an asteroid. A natural way to model verification — comparison with reality. Because the experiment with a real asteroid is planned, the researchers decided to turn to the test of 1991, in which Japanese scientists took a high speed camera shot at a six-centimeter-round piece of basalt, simulating the asteroid, plastic bullet, flying at a speed of 3.2 kilometres per second.

It is noteworthy that in contact with the opposite side of the stone formed the characteristic spalling (spall), and that, not the motrya on the huge energy impact, not all of the basalt crumbled into small pieces: preserved large core stone. This gave the researchers an effective way of assessment of the tested models, because in the first place they checked, if calculations of intact core and the breakaway back.

Applied physics computer model of a rigid body discrete: the objects is not continuous but broken up into small three-dimensional pieces. The more model fragments, the more accurate the calculation, but also higher computational complexity. Therefore, the first step of the scientists was to determine the required number of “pixels”. To do this, they have started modeling a collision with a deliberately low detail, and gradually increased, while ROS resulting virtual asteroid damage. The number of fragments is increased as long as the growth of the damage came on a plateau, that is, until the increase of detail has not ceased to benefit. In the end, a virtual asteroid coctail of the nearly two million fragments with a diameter of 150 fragments.

The next problem was the choice of the principle for calculating the mechanical stress of the basalt, for which the researchers considered two relevant models: the deformation model Benz Asfaha (Benz Asphaug) and pseudoplasticity model deformation. Only the first model given the observed in vivo experiment, a core and a chip on the back side. Her damage seemed to be around the center, while in pseudoplasticity model for the fracture passed through the whole body.

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