NASA announced today (on the evening of Sol 51), that Curiosity Rover has found evidence of an ancient “vigorously” flowing water stream on Mars. The arrangement in the picture to the left is what geologists call a sedimentary conglomerate and is composed of exposed bedrock made up of smaller fragments cemented together (similar to arrangements found on Earth). The up-tilting outcrop, which NASA said “looked like someone had come along and lifted up the rock with a jackhammer”, gave NASA a chance to view the materials exposed within and underneath the rock.
The rock outcrop pictured here, which was first spotted by a Mars orbiter, as been named “Hottah”. Hottah has pieces of gravel embedded in it, called “clasts”. The size and shape of the clasts offer clues to the speed and distance of moving water. Some of the clasts are round-shaped, ranging in size from a grain of sand to a golf ball, leading Geologists to the conclusion that they have been moved about by “vigorously moving water”. The clasts are too heavy to have been moved by wind.
Curiosity science co-investigator William Dietrich said:
“The shapes tell you they were transported and the sizes tell you they couldn’t be transported by wind. They were transported by water flow. 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.”
They estimated that the water flow lasted for more than 1,000 years.
“Now that we’re down on the ground with Curiosity we can see the textural evidence, the individual pebbles, the rounding that gives us a sense of that. It wasn’t a single burst of water that ran down the canyon all in a day. There are too many things that point away from that. How long would it take? This is opening the door to answering that question.”
The finding site lies between the north rim of Gale Crater and the base of Mount Sharp, a mountain inside the crater. NASA said this was an exciting discovery for them because evidence of the presence of water on Mars was one of their primary reasons for this expedition. They are hoping to find additional evidence as Curiosity continues to Mount Sharp and Glenelg, its ultimate destination.
“A long-flowing stream can be a habitable environment. 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.”
Below are some pictures that NASA shared in their news conference.
Complete video from the NASA news conference below, including the questions and answers session at the end of the announcement.