Mars is a fascinating planet. Today, it appears cold and dry, much like a desert, with some ice hidden beneath its surface and at its poles. However, long ago, water flowed freely across the Martian landscape. NASA’s rovers have found many clues suggesting that liquid water once existed on Mars, but recent discoveries offer even more exciting evidence.
In November 2022, NASA’s Curiosity rover took images of the Amapari Marker Band in the foothills of Mount Sharp, located in Gale Crater. In this thin, dark layer of rock, scientists spotted wave ripples that indicate there used to be a sandy shoreline. Shortly after, another set of wave ripples was found nearby in the Prow outcrop, suggesting they were once part of the lake bed.
These ripples are believed to have formed about 3.7 billion years ago when Mars was in the process of drying out. However, their presence suggests that at that time, Mars had a warmer climate and wet surfaces. According to Caltech researcher Caire Mondro, “The shape of the ripples could only have been formed under water that was open to the atmosphere and acted upon by wind.” This suggests that the water was likely not frozen, as some scientists had previously thought.
Using computer models, Caltech geologist Michael Lamb estimated that this ancient lake was likely less than six feet (two meters) deep. This shows us just how different Mars once was, with shallow lakes that could have supported some form of life.
While earlier missions, like Opportunity in 2004, discovered evidence of flowing water on the Martian surface, there was still uncertainty about whether this water pooled into lakes or shallow seas. John Grotzinger, a former project scientist for Curiosity, noted, “The Curiosity rover discovered evidence for long-lived ancient lakes in 2014. Now, ten years later, it has uncovered lakes that were free of ice, offering valuable insights into the planet’s early climate.”
This exciting discovery is significant because it adds to our understanding of Mars and its potential to support life in its distant past. A paper detailing these findings was published in the journal Science Advances on January 15.
