Study suggests life created by asteroid collisions
USA Today
Dec. 11, 2008
By Dan Vergano
Asteroid impacts, which have been fingered for killing off the dinosaurs and other mass extinctions, may have helped kick-start life in the first place, experiments by Japanese researchers suggest.
Earth's oceans formed about 4.3 billion years ago, a time when lunar craters suggest Earth suffered a bombardment of comet and asteroid chunks, note the researchers led by Yoshihiro Furukawa of Japan's Tohoku University. How life's complex chemical building blocks -- "organic" molecules, such as amino acids -- accumulated on Earth amid extraterrestrial impacts and the vibrant volcanism of a young planet has intrigued researchers for decades.
In the study, the team reports the results of blasting simulated asteroid pieces with a propellant gun into a water and ammonia mix meant to simulate the early ocean. The goal was to re-create a 4,500-mph dive into the ocean that blasted apart iron and carbon meteorites at 8,500-degree temperatures.
"This report lends support to the exciting hypothesis that terrestrial planets and icy moons are predisposed to origins of life" delivered by carbon-rich meteorite impacts, says astrobiologist Lisa Pratt of Indiana University in Bloomington. The new study has the "unexpected twist" of adding newly formed organic molecules from the impact event to any matter already inside the meteorite, Pratt says.
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