June 14, 2011 at 1:00 PM ET
Imagine traveling all the way to Mars and crawling out of the lander to take that historic first step only to get smacked on the head by a meteorite. It could happen. Really. Meteorites rain down on the Red Planet much more frequently than they do on Earth.The HiRISE camera on the Mars Reconnaisance Orbiter recently beamed down this latest evidence of a space rock bombardment. Analysis of the image suggests the series of craters were formed as a large meteoroid broke up in the Martian atmosphere and peppered the surface like cosmic buckshot. The impact happened sometime between December 2002 and March 2008.
The reason Mars gets hit by more meteorites than Earth comes down to the difference between the two planets' atmospheres. Earth's is about 100 times thicker than Mars', which means most space rocks burn up in our atmosphere, creating what we see as shooting stars and fireballs, but few impact craters.
On Mars, more of the space rocks survive the journey through the atmosphere and hit the surface, Ian O'Neill explains for Discovery News. This is why any would-be Mars explorers might want to pack a hard hat for the journey.
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John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).