10 years later, scientists figure out how the Chelyabinsk meteorite broke up

Planetary defense scientists have spent the last three years simulating and simulating the decay of the atmosphere of the famous Chelyabinsk meteorite.

On the morning of February 15, 2013, a small asteroid exploded over this Russian city, sending a massive shockwave and sonic boom across the region, damaging buildings and injuring about 1,200 people. He meteorite The resulting rock, about 20 meters in diameter (the size of a six-story building), was one of the largest discovered in the Earth’s atmosphere in the last hundred years.

Their study highlights the important role of material strength and fracture in fracture dynamics.

unique event

Although several research organizations have studied the occurrence Chelyabinskscientists at LLNL (Livermore Lawrence National Laboratory) were the first to model Chelyabinsk meteorite in full 3D with a material model based on meteorite survey data extracted from this event. Unlike historical meteor events, the 2013 ejecta was captured by mobile phones and CCTV cameras from various angles, and a 500-kilogram fragment was found in Lake Chebarkul shortly after the impact.

Their modeling, which is largely consistent with observed events, suggests that the object could be a monolithic or solid piece of rock. If so, according to the researchers, the strength and fracture of the material played an important role in the rupture of the object and the resulting shock wave.

“This is something that can only be captured with 3D modeling,” explains Jason Pearl, principal investigator on the project, in a statement. When LLNL’s expertise in impact physics and hydrocoding is combined with the laboratory’s high-performance computing capabilities, we have a unique 3D meteor simulation capability.”

“Our study highlights the importance of using such highly accurate models to understand asteroid explosions,” says Pearl. “Many of the smaller asteroids are rubble piles or clumps of loose space gravel, so the possibility of a monolith is really interesting.”

The research team used smoothed particle hydrodynamics (SPH), a computational technique used to model the dynamics of rigid body mechanics and fluid flows, to study the discontinuity mode of a monolithic asteroid of size Chelyabinsk.

In their simulations, the team found that the explosion occurs when large cracks form on the back of the asteroid under tensile stress. The crack propagation timeline to the front of an asteroid determines when an asteroid breaks into smaller fragments upon entry into the Earth’s atmosphere.

Then, a family of fragments near the shock wave front temporarily shields the region of completely damaged material until, approximately 30 km above the Earth’s surface, undamaged fragments separate and the fragments enter free flow. Eventually, the debris cloud slows down rapidly, and the remaining fragments continue to break apart into smaller chunks of rock.

The decay process is rich in physics, explained Mike Owen, a physicist at LLNL. The connection of an asteroid with the atmosphere depends on its surface. The larger the surface area, the more the object is exposed to heat, stress, and pressure.

“When an asteroid enters the atmosphere, it’s kind of a catastrophic failure,” explains Owen. “And it tends to shrink in the direction of motion. It was as if the asteroid was contracting in the direction of motion, breaking up into separate parts that began to separate and disintegrate perpendicular to the direction of motion.

“Suddenly, a lot more material is being hypersonically interacted with air, a lot more heat, a lot more stress, which causes it to break down faster, and there’s a kind of cascade process.”

Preventing the future

A better understanding of the decay process can be used to build better statistical models of the risk associated with planet-sized asteroids. Chelyabinsk. According to LLNL’s Cody Raskin, one of the main contributors to the project, understanding how these objects break apart and transfer their energy into the atmosphere is critical to getting an accurate assessment of the damage they could cause and can help develop better response strategies. . , Civil defense.

The long-term goal of this study will be to use these models to estimate the ground effects of a future meteor, predicting the region that may be affected. (Europe Press)

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