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Whole lotta shaking goin' on in space

Researchers studied high-resolution photos of the near-Earth asteroid Itokawa and learned that its surface which is made up of small grains and boulders has been sorted when the asteroid was shaken.

In June 2006, Science magazine published a special report about the Japanese spacecraft Hayabusa hovering over the Itokawa asteroid to take pictures of its surface The goal was to understand what the near-Earth asteroid is made of and how granular materials act in the low gravity environment of space. Most asteroids look like a solid rock, but Itokawa looked like it was covered with rubble.

Itokawa is one of the smaller asteroids. It is only 500 meters long the length of 10 Olympic size swimming pools and is shaped like a sea-otter.

Hideaki Miyamoto and a group of international researchers analyzed the clear images of from the Hayabusa spacecraft. Because the images were of such high resolution, researchers could see gravel just centimeters in size.

Researchers determined that the rubble covering the asteroid has been sorted by shaking in a way that the smallest materials are together in the areas of the lowest local gravity. Clumps of larger rocks suggest that the Itokawa is also stirred up from below.