A popular theme in films is when an asteroid approaches the planet that threatens to destroy all life, and a team of superheroes goes into space to blow it up. But approaching asteroids may be harder to break than previously thought, a study from Johns Hopkins University shows. Scientists have simulated an asteroid impact and gained a new understanding of rock breaking. The work will be published in the Icarus magazine on March 15.
Its results could help create strategies for countering and deflecting asteroids, improve understanding of the formation of the solar system, and help develop useful resources on asteroids.
How to destroy an asteroid?
Scientists understand the physics of materials - like rocks - on a laboratory scale (studying them from fist-sized samples), but it's hard to translate this understanding to objects the size of a city, like asteroids. In the early 2000s, other scientists created a computer model that could enter various factors, such as mass, temperature, and fragility of the material, and simulate an asteroid about a kilometer in diameter hitting a target asteroid 25 kilometers in diameter at a speed of 5 km / s. Their results indicated that the target asteroid would be completely destroyed by the impact.
In a new study, El Mir and his colleagues introduced the same scenario into a new computer model of Tonge-Ramesh, which takes into account the small-scale processes that take place during the collision in more detail. Previous models did not take into account the limited velocity of crack propagation in asteroids in a proper way.
The modeling was divided into two phases: a short-term fragmentation phase and a long-term gravitational reacumulation phase. In the first phase, processes were considered that begin immediately after the asteroid hits the target, processes that are fractions of a second long. The second phase, which is longer, involves the effect of gravity on the parts that fly off the surface of the asteroid after impact; many hours after the collision, gravitational reacumulation also occurs, the asteroid is reassembled under the influence of its own gravity.
In the first phase, after the asteroid was hit, millions of cracks formed on it, part of the asteroid melted, and a crater appeared at the site of impact. At this stage, individual cracks were studied and the general patterns of propagation of these cracks were predicted. The new model showed that the asteroid would not crumble on impact, as previously thought. Moreover, since the asteroid did not collapse in the first phase of the collision, it even became stronger in the second phase: the damaged fragments were redistributed around a larger, new core. As a result of the study, it was necessary to revise both the energy required to destroy the asteroid and the possible loopholes to the interior of the asteroid for those who would like to develop it.
Ilya Khel