Research on the Chelyabinsk Meteor by SSERVI PI David Kring (LPI) and Mark Boslough (Sandia National Lab) was featured as the cover story of Physics Today magazine.

Below is an excerpt from the section titled “Impact airbursts versus impact craters:”

The Chelyabinsk airburst was roughly two orders of magnitude more energetic than the approximately 10-kt Sikhote-Alin asteroid event of 1947 and roughly an order of magnitude less energetic than the 3- to 15-MT Tunguska blast of 1908. The considerable uncertainty in estimates of the energy of those and other relatively small impact events makes it difficult to quantify future hazards. For that reason, the Chelyabinsk impact event is incredibly important: It produced the first high-precision values for the energy of a blast and the ground damage it caused.

Fortunately, Earth’s atmosphere screens most objects from reaching the surface with cosmic velocities. Some objects are large enough and strong enough, however, to penetrate deeply into the atmosphere before exploding in an airburst or reaching Earth’s surface to produce a crater.

Although stony near-Earth asteroids dominate the impact flux, nearly all of the smallest craters on Earth were produced by iron asteroids. Small stony asteroids, like Chelyabinsk, preferentially produce airbursts before reaching the ground. Small iron asteroids, however, survive atmospheric passage and cause explosions at the surface that excavate impact craters. The most famous is the 49 000-year-old Barringer meteorite crater in northern Arizona. That breathtaking impact site was produced by a roughly 30-m-diameter iron asteroid, remnants of which are known as the Canyon Diablo meteorites.

Although the Barringer crater’s 1.2-km diameter is relatively small compared with some of Earth’s largest, such as the dinosaur-killing Chicxulub impact crater, 180 km in diameter, the kinetic energy of Barringer’s impact is sufficient to destroy a modern city. The pressure pulse and airblast can be devastating. The blast was immediately lethal for human-sized animals within 6 km of it. Those within 10–12 km suffered severe lung damage from the pressure pulse alone. Winds in excess of 1500 km/h were produced within the inner 6-km-diameter zone and still exceeded 100 km/h at radial distances of 20 km.

Photos of the meteor, fragments, and a microscopic view of the interior of the meteorite can be found in the full article. Read the full article here

Posted by: Soderman/SSERVI staff
Source: SSERVI Team

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