NASA's Curiosity Rover Finds Remnants of Ancient Streambed on Mars

Posted on September 27, 2012

NASA's Curiosity rover has found remnants of an ancient streambed on Mars. NASA has named the site Hottah after Hottah Lake in Canada's Northwest Territories. NASA says the evidence for the ancient stream size and rounded shape of the gravel in and around the bedrock.

The key evidence for the ancient stream comes from the size and rounded shape of the gravel in and around the bedrock. Hottah has pieces of gravel embedded in it, called clasts, up to a couple inches (few centimeters) in size and located within a matrix of sand-sized material. Some of the clasts are round in shape, leading the science team to conclude they were transported by a vigorous flow of water. The grains are too large to have been moved by wind.
You can see a close-up of these rounded gravel calsts here.

Curiosity science co-investigator William Dietrich of the University of California, Berkeley, said in a statement, "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. 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."

The Hottah site lies between the north rim of Gale Crater and the base of Mount Sharp. Mount Sharp remains Curiosity's main destination because the clay and sulfate materials NASA detected there are good preservers of carbon-based organic chemicals, which are potential ingredients for life.

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