Less than two months into its mission, Curiosity found evidence of an ancient streambed on Mars that once had “vigorous” water flow.
The evidence came in the form of an outcropping of rocks between the north rim of Gale Crater and the foot of Mount Sharp, that appears to have been heaved up and covered with streambed gravel. The rover drove by the outcropping, which had earlier been spotted by one of NASA’s Mars orbiters. NASA JPL scientists think that the small stones were previously moved because of their shape. Their size (grain-big to golf ball-size) are a telltale sign that water did the work instead of wind. Evidence of H2O on Mars has been spotted before, but this is the first direct look at the composition of riverbeds NASA has observed from above.
“We found interesting outcrops,” said John Grotzinger, a project scientist with NASA’s Jet Propulsion Laboratory and a geology professor at the California Institute of Technology. “It looks like someone came along with a jackhammer and lifted up a sidewalk… This is a rock that was formed in the presence of water… a vigorous flow in the surface of Mars. We are really excited about this because this is the reason we came to this site.”
According to William Dietrich, Curiosity science co-investigator, it’s estimated that water flowed at the site anywhere from thousands to millions of years ago, moved at a clip of roughly 3 feet per second and was somewhere between ankle and hip deep.
“A long-flowing stream can be a habitable environment,” Mars Science Laboratory Project Scientist John Grotzinger said. “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.”
Now that scientists have proof that water once flowed across Mars, they can begin to look for signs of other elements, such as carbon, that are also needed to support life.