![]() ![]() The break-up of the meteoroid was characterized by intense fragmentation that dispersed most of the original mass. The entry and subsequent break-up of the ~ 17-20 m diameter Chelyabinsk meteoroid deposited approximately 500 kT of TNT equivalent energy to the atmosphere, causing extensive damage that underscored the hazard from small asteroid impacts. Writer: Kayla Zacharias, 76, Jay Melosh, 76, to journalists: A copy of the paper is available here.Īir penetration enhances fragmentation of entering meteroids This research was supported by NASA’s Office of Planetary Defense under grant NNX14AL15G. Iron meteoroids are much smaller and denser, and even relatively small ones tend to reach the surface. While this mechanism may protect Earth’s inhabitants from small meteoroids, large ones likely won’t be bothered by it, he said. This new code allowed the researchers to push air into the meteoroid and let it percolate, which lowered the strength of the meteoroid significantly, even if it had been moderately strong to begin with. Different materials in the cell use their individual identity, which is not appropriate for this kind of calculation.” “Most of the computer codes we use for simulating impacts can tolerate multiple materials in a cell, but they average everything together. “I’ve been looking for something like this for a while,” Melosh said. To solve the puzzle, the researchers used a unique computer code that allows both solid material from the meteor body and air to exist in any part of the calculation. The meteoroid weighed around 10,000 tons, but only about 2,000 tons of debris were recovered, which meant something happened in the upper atmosphere that caused it to disintegrate. Minutes later, a shock wave blasted out nearby windows, injuring hundreds of people. When it entered Earth’s atmosphere, it created a bright fire ball. The explosion came as a surprise and brought in energy comparable to a small nuclear weapon. Melosh’s team looked to the 2013 Chelyabinsk event, when a meteoroid exploded over Chelyabinsk, Russia, to explain the phenomenon. Researchers knew that meteoroids often blew up before they reached the Earth’s surface, but they didn’t know why. “If the air can move through the passages in the meteorite, it can easily get inside and blow off pieces.” “There’s a big gradient between high-pressure air in front of the meteor and the vacuum of air behind it,” said Jay Melosh, a professor of Earth, Atmospheric and Planetary Sciences at Purdue University and co-author of the paper. When a meteor comes hurtling toward Earth, the high-pressure air in front of it seeps into its pores and cracks, pushing the body of the meteor apart and causing it to explode. Our atmosphere is a better shield from meteoroids than researchers thought, according to a new paper published in Meteoritics & Planetary Science. ![]()
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