Curiosity Rover Spots Ancient Water Ripples on Mars, Hinting at a Past With Shallow, Ice-Free Lakes

Wave ripples—the undulating lines in sandy shores that form when the wind pushes shallow water back and forth—are a common sight on Earth’s lakes and beaches. Now, NASA’s Curiosity rover has identified two sets of ancient wave ripples on Mars, suggesting the presence of standing bodies of liquid water billions of years ago. Curiosity discovered the ripples in Mars’ Gale Crater region in 2022, as detailed in a study published this month in the journal Science Advances.

“We have been searching for these features since the Opportunity and Spirit landers began their missions in 2004,” co-author John Grotzinger, a geologist at the California Institute of Technology and former project scientist for Curiosity’s mission at NASA’s Mars Science Laboratory, says in a statement.

Previous missions “discovered ripples formed by water flowing across the surface of ancient Mars, but it was uncertain if that water ever pooled to form lakes or shallow seas,” Grotzinger continues. In 2014, Curiosity identified evidence of long gone but “long-lived” Martian lakes, “and now, ten years later, Curiosity has discovered ancient lakes that were free of ice, offering an important insight into the planet’s early climate,” he adds.

The body of water that created the ripples must have been exposed to the wind, which is why the scientists deduced it was not covered in ice. In fact, solidified wave ripples are one of the most direct pieces of geological evidence for ancient bodies of standing water, per the statement.

Curiosity found that the ripples are about 1.57 to 1.97 inches apart and approximately 0.24 inches high. The team plugged these measurements into a computer model, which used them to predict the presence of an ancient lake less than about 6.5 feet deep.

Both sets of ripples are approximately 3.7 billion years old, but one is slightly older than the other. This suggests that atmospheric conditions allowed for the formation of standing water more than once in the planet’s history.

The study joins a host of previous research proposing that, though Mars lost most of its atmosphere around the same time the ancient ripples formed, its bodies of water didn’t immediately vanish.

“We can start to see that Mars didn’t just have one wet period early in its history and then dried out,” Edwin Kite, a geophysicist at the University of Chicago who led a previous study on ancient Martian rivers, told Space.com’s Mike Wall in 2019. “It’s more complicated than that; there were multiple wet periods.”

The longer water existed on Mars’ surface, the more opportunities potential life could have had to evolve and inhabit the red world, Claire Mondro, a planetary geologist at the California Institute of Technology, explains in the statement.

The discovery of the water ripples could influence future missions to Mars, suggests Eric Ralls of Earth.com. In fact, another team of scientists has recently investigated how water might have shaped Mars’ mysterious geology to inform an upcoming European Space Agency mission.

“The mounds in Chryse Planitia [a plain on Mars] are rich in clay minerals, meaning liquid water must have been present at the surface in large quantities nearly four billion years ago,” Joe McNeil, a planetary scientist at the Natural History Museum in London and co-author of another study that came out earlier this year, said in a recent statement. “The European Space Agency’s upcoming Rosalind Franklin rover will explore nearby and could allow us to answer whether Mars ever had an ocean, and if it did, whether life could have existed there.”

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.