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"  Just 52 days since arriving on the Martian surface, NASA&amp;#039;s Curiosity rover (officially called the Mars Science Lab) made its first major discovery, sending back pictures of tiny rounded pebbles\u2014evidence of a stream that once flowed on the planet&amp;#039;s surface. Although not the first proof of liquid water on Mars, Curiosity&amp;#039;s find of streambed gravel is a scientific first. The pebbles\u2014which would not look out of place in any stream on Earth\u2014not only suggest liquid water was on the Red Planet, but that they were part of a stream that had been flowing for quite some time. &amp;quot;This is something that would have required thousands of years, if not a million or more years, to form,&amp;quot; says Mars Science Laboratory project scientist John Grotzinger of Caltech. This suggests that the stream Curiosity snapped photos of was flowing on the planet&amp;#039;s surface much longer than previously thought possible, he says. &amp;quot;The only thing that comes close to that is what we found with the Opportunity rover,&amp;quot; says Grotzinger. &amp;quot;We found evidence of a little bit of a flow across the surface, but in that case it was something that would have only lasted a very, very brief period of time.&amp;quot; At best the stream Opportunity found lasted only minutes to hours, Grotzinger says. Based on the science team&amp;#039;s estimates, the ancient stream was flowing &amp;quot;about 3 feet per second, with a depth somewhere between ankle and hip deep,&amp;quot; says William Dietrich, Curiosity science co-investigator of the University of California, Berkeley, in a press release. &amp;quot;This really represents the thing we must have found on this mission in order to go to the next level with Curiosity&amp;#039;s science mission,&amp;quot; says Grotzinger. &amp;quot;And that is this question of habitable environments.&amp;quot; If the Mars Science Laboratory is to find signs of life, then there are few better places to look than a giant, long-flowing stream. &amp;quot;We just have to keep our fingers crossed, he says. &amp;quot;And really hope for some serious luck here to find the organic carbon.&amp;quot; "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/space/moon-mars/a8191/nasas-mars-rover-discovers-direct-evidence-of-flowing-water-13138895/>