* Astronomy

NASA Probe Counts Space Rock Impacts on Mars

Scientists using images from NASA's Mars Reconnaissance Orbiter (MRO) have estimated that the planet is bombarded by more than 200 small asteroids or bits of comets per year forming craters at least 3.9 meters across.
Researchers have identified 248 new impact sites on parts of the Martian surface in the past decade, using images from the spacecraft to determine when the craters appeared. The 200-per-year planetwide estimate is a calculation based on the number found in a systematic survey of a portion of the planet.
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