A recent study published in the Proceedings of the National Academy of Sciences reveals that Mars may have once hosted sandy beaches and a vast ocean, suggesting the planet had a more habitable environment for life in the past. The findings provide some of the clearest evidence yet that Mars had liquid water on its surface and conditions that could have supported microbial life.
The research is based on data collected by China's Zhurong Mars rover, part of the Tianwen-1 mission, which utilized ground-penetrating radar to uncover hidden layers of rock beneath Mars's surface. An international team of scientists, including researchers from Pennsylvania State University, analyzed the data and identified formations that strongly suggest the presence of an ancient northern ocean.
"We're finding places on Mars that used to look like ancient beaches and ancient river deltas," explained Dr. Benjamin Cardenas, an assistant professor of geology at Pennsylvania State University and a co-author of the study, according to SciTechDaily. "We found evidence for wind, waves, no shortage of sand—a proper, vacation-style beach," Cardenas added.
The radar data revealed a layered structure similar to Earth's beaches, with particle sizes in these layers matching those of sand, suggesting the influence of wind and waves. This discovery supports the idea that Mars had a dynamic, watery environment billions of years ago. "The structures don't look like sand dunes. They don't look like an impact crater. They don't look like lava flows. That's when we started thinking about oceans," commented Michael Manga, professor of Earth and planetary science at the University of California, Berkeley, according to Discover Magazine. "The orientations of these features are parallel to what the old shoreline would have been. They have both the right orientation and the right slope to support the idea that there was an ocean for a long period of time to accumulate the sand-like beach," Manga further stated, as reported by Science Alert.
Scientists now believe that warm, wet conditions on Mars may have persisted for tens of millions of years—long enough for life to possibly take hold. "This finding enhances the idea that the Red Planet was once a potential environment for life, as new research provides the clearest evidence yet that Mars once contained a significant body of water and a more habitable environment for life," according to SciTechDaily. At that time, Mars had a denser atmosphere and a warmer climate, which would seemingly increase the odds that life could have existed there.
The presence of beaches on Mars indicates that it once had a large, ice-free ocean, likely during a time when the planet had a warmer and thicker atmosphere, suggesting the possibility of ancient life. "When we look back... to where the oldest life on Earth evolved, it was in the interaction between the oceans and the land, so this discovery paints a picture of ancient habitable environments capable of hosting conditions suitable for microbial life," stated Cardenas. "This type of sedimentary geology can tell us what the landscape looked like, how they evolved, and, importantly, help us identify where we would want to look for past life," he said.
The capabilities of the Zhurong rover have allowed scientists to understand the geologic history of Mars in an entirely new way. Ground-penetrating radar sends radio waves into the ground, generating a three-dimensional map of structures deep below, which has enabled researchers to identify and plot different layers of rock and soil beneath the surface.
These findings strengthen the hypothesis that Mars's northern plains once hosted a large and persistent ocean, adding evidence that nearly half of Mars was once covered by oceans. Coastal areas are considered conducive to the emergence of life, as they offer nutrients, energy gradients, and protected niches where primitive organisms can thrive.
The discovery suggests a place to look for signs of ancient life on Mars. While the Zhurong rover was not equipped to search for biosignatures, its findings help narrow down promising locations for future missions seeking signs of past life. "Though no one knows whether Mars was ever inhabited, the presence of an ocean means this location was at least habitable," noted Cardenas. "This indicates the presence of environments conducive to life, capable of maintaining conditions friendly to microorganisms," he stated. The new evidence from the Zhurong rover provides a fresh perspective by peering beneath the surface, where geological structures remain better preserved from billions of years of erosion, impacts, and dust storms.
The article was written with the assistance of a news analysis system.