February 28, 2012
Study Finds Space Dust Gives Asteroids Their Shape
Japanese researchers discovered while studying grains of dust from the Itokawa asteroid that tiny particles of space dust bombard asteroids and give them their shape.
The researchers analyzed the size, mineralogy, shape and geochemistry of five dust grains recovered by the Japanese asteroid probe Hayabusa.
Hayabusa succeeded in returning over 1,500 grains of dust from the asteroid Itokawa when it parachuted into the Australian outback in June 2010.
"Our findings show the landscape itself of the very surface of an asteroid," Eizo Nakamura, who worked on the study with colleagues at Okayama University in Tsushimanaka, Japan, said in a statement. "An asteroidal surface is not a quiet place, but is heavy with bombardment."
The team examined five dust grains from Itokawa's surface, each measuring just 40 microns across, which is less than half the width of a human hair. They used electron microscopy to look at surface features.
"Our analysis is the initial analysis only, using five tiny particles," Nakamura said in a press release. "There remain thousands of particles preserved [by] JAXA, so further analyses following our methodology will enable better understanding of space environments on small asteroids."
The researchers found evidence of hundreds of collisions with space dust, indicating that nanoparticles were traveling at tens of thousands of miles per second.
This tremendous speed resulted in high-energy impacts, changing the chemical properties of the asteroidal surface and producing enough heat for localized melting.
The new research helps identify the processes underlying "space weathering", which explains differences in general properties of asteroid surfaces.
Nakamura said asteroids are the "most primitive solar bodies" and can be used to give scientists insight about the formation of the Solar System, its history and the processes that have helped shape it.
The study was published in the Proceedings of the National Academy of Science.
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