The Curiosity rover has discovered evidence of streambed gravel on Mars -- signifying that a waterway once flowed on the red planet.
"From the size of gravels it carried, we can interpret the water was moving about 3 feet per second, with a depth somewhere between ankle and hip deep," said Curiosity science co-investigator William Dietrich of the University of California, Berkeley. "Plenty of papers have been written about channels on Mars with many different hypotheses about the flows in them. This is the first time we're actually seeing water-transported gravel on Mars. This is a transition from speculation about the size of streambed material to direct observation of it."
A rock outcrop can be seen in the Curiosity image, which scientists have dubbed "Hottah" after Hottah Lake in Canada’s Northwest Territories.
"Hottah looks like someone jack-hammered up a slab of city sidewalk, but it's really a tilted block of an ancient streambed," said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology in Pasadena.
Researchers will use Curiosity's built-in lab to analyze the Martian streambed, in hopes of determining if microbial life ever existed on Mars.