Hayabusa Asteroid Samples Depict Frequent Impacts

摘要

The first dust grains ever retrieved from the surface of an asteroid confirm that these space rocks are constantly shaped by a continuous barrage of high-speed microscopic impacts, scientists have found. The Japanese asteroid probe Hayabusa succeeded in returning more than 1,500 grains of dust from the asteroid 25143 Itokawa when it parachuted into the Australian outback in June 2010. Already, the samples from this 550-meter-long asteroid have helped solve the longstanding mystery of where most meteorites striking Earth come from.