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Asteroids, Meteorites and Purdue — Oh my!


Prof. Jay Melosh

Back in February, the science world was abuzz with the route of asteroid DA14. The 50-meter-wide space rock whizzed by Earth only 17,000 miles away — closer than some communications satellites.

DA14 careened by on the afternoon of Feb. 15 without incident but just several hours before it made its pass, a smaller visitor from space — a 60-foot-wide meteorite — exploded over the Chelyabinsk Oblast region of Russia. The meteorite was traveling at 41,000 miles per hour or 50 times the speed of sound. The explosion was brighter than the sun and it knocked out windows in buildings miles away. 

Purdue College of Science experts were sought out for these space phenomena. Physics Prof. David Miller returned to the radio airwaves with an entertaining interview on a CBS-run Washington, D.C., radio station while Jay Melosh, distinguished professor in Earth, Atmospheric, and Planetary Sciences and Physics, made media rounds on his “what-if” scenarios on DA14.

If the asteroid did impact rather than nearly miss Earth, it would have exploded with a four-megaton force near what the military calls optimum height for damage, Melosh said.

Melosh continued: DA14 would have released only half the energy of the Siberian strike in 1917 that leveled thick forest for 20 miles in every direction. But the 30,000-foot detonation height would cause significant property damage and loss of life, especially if the asteroid were to explode over a metropolis like New York or Chicago.

"We're talking about an airburst with the power of a mid-size thermonuclear weapon, with similar results," Melosh said. "The worst damage would be directly beneath the explosion but windows and wood buildings 15 miles out would be imperiled."

Melosh modeled a hypothetical impact with Impact:Earth!, the interactive website he created that is used for disaster planning purposes by safety officials from agencies that include the Federal Emergency Management Agency and Department of Homeland Security.

On National Public Radio, Melosh spoke on technology that might divert an incoming asteroid.

Melosh is an internationally renowned impact crater expert who has worked with NASA science teams to determine if Martian moons reveal evidence of microbial life, how the moon was formed from core to crust and how an asteroid strike may have prompted prehistoric mass extinction on Earth.

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