NASA’s Curiosity rover recently discovered some of the most compelling evidence of ancient water on Mars. This evidence is rippled stones formed by the waves.
These ripples formed billions of years ago when the surface of Mars was still covered with water. Probes around the planet are exploring these ancient water basins to learn about Mars’ geological history and its potential for astrobiology.
Curiosity began its mission in 2012 in the low-altitude Gale Crater and is currently on Mount Sharp, which was once covered in lakes and streams. If life once existed on Mars, these ancient waterways are a good place to look.
The rover spotted rock textures — small ripples that look like dried tire treads — in a layer of rock on Mount Sharp in a region called the Marker Band Valley, according to a press release by NASA.
“This is the best evidence of water and waves that we’ve seen in the entire mission,” said Ashwin Vasavada, Curiosity’s project scientist. “We climbed through thousands of feet of lake deposits and never saw evidence like this – and now we found it in a place we expected to be dry.”
The Marker Band and its surroundings formed in a drier climate than the areas Curiosity has already passed through. In other words, the NASA team suggested that water on Mars might have already disappeared by the time the rock under study formed.
There are ice sheets and ice caps at the poles of Mars, and the impact of meteorites on the planet has led to the formation of subsurface ice, but there has been no liquid water on the planet for billions of years, at least as far as we know. Mars is cold and has a thin atmosphere, so water freezes on its surface, and the planet’s ancient water is now believed to have mostly been lost to space (according to the data by NASA, at least 87%).
The Marker Band is so hard that Curiosity couldn’t get a sample from it even after several drilling attempts, but if the rover can’t get a sample from the softer rock, it’s still in for an exciting adventure.
The Martian valley Gediz Vallis contains many rock fragments that, according to scientists, were brought there by ancient landslides. This makes the valley a repository of rocks from the top of Mount Sharp that Curiosity will not be able to reach. By studying these boulders, scientists will gain insight into previously unavailable stories from Mars’ past.