Water Was on Mars as Curiosity Finds Ancient Streambed

NASA's Curiosity rover has found remnants of a stream on the Mar's surface.

The image of rocks captured by the rover on its current driving path between the north rim of Gale Crater and the base of Mount Sharp contains ancient streambed gravels which gives out a new evidence of the presence of water on Mars.

"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," Curiosity science co-investigator William Dietrich of the University of California, Berkeley, said in a news release from NASA.

 "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," he said.

The new evidence came to light when scientists observed two outcrops - Hottah and Link after reviewing images of the outcrops taken by rover's mast camera.  They found that Hottah is actually a tilted block of ancient streambed. These rock outcrops are said to have gravels collected as a whole in different sizes and shapes such as angular and rounded which were possibly transported by the water flow.

Although exact timeframe of the flow of stream could not be estimated, experts have found some clues about it. Based on images that were taken from Mar's orbit, experts found there is an alluvian fan of material which washed away from the rim of Gale crater. The alluvian fan has several water channels sitting uphill of both the Link and Hottah rock outcrops. The occurrence of more number of channels between the rim and the rock conglomerate suggests that the stream did not occur once, but continued for a long time.

Curiosity's ultimate destination will be Mount Sharp, a mountain in Gale crater which has different compositions of sand that could be identified based on its color, to search for habitable environment. This new finding of an ancient stream flow has already given potential evidence of the presence of environment that could have supported life, said NASA scientists.

"A long-flowing stream can be a habitable environment," said John Grotzinger, of the California Institute of Technology and Mars Science Laboratory Project Scientist.

"It is not our top choice as an environment for preservation of organics, though. We're still going to Mount Sharp, but this is insurance that we have already found our first potentially habitable environment," he said.

Curiosity which landed on Mars on Aug. 5 is on a two-year mission in search of chemical elements on the Martian soil that could have possibly supported microbial life.