This image taken by the NASA rover Curiosity shows sediment at the bottom of an ancient streambed on Mars. Fresh analysis by Curiosity reveals hundreds of rounded pebbles in its Gale Crater landing ... more 
This image taken by the NASA rover Curiosity shows sediment at the bottom of an ancient streambed on Mars. Fresh analysis by Curiosity reveals hundreds of rounded pebbles in its Gale Crater landing site - a sign that a liquid once flowed there. (AP Photo/NASA) less 
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Associated Press | Photo By NASA
Thu, May 30, 2013 3:59 PM EDT