Four billion years ago, Mars might have been the ultimate summer vacation spot. Scientists have uncovered evidence suggesting that the red planet once had sandy beaches and a vast ocean on its surface. These findings come from data collected by China’s Zhurong rover, which explored Mars from May 2021 to May 2022. The rover traveled about 1.2 miles (1.9 km) on the planet and detected thick layers of sand-like material buried 35-115 feet below the surface. These deposits were sloped in the same direction and at the same angle, resembling beaches on Earth, and stretched for three-quarters of a mile. This discovery, published in the journal Proceedings of the National Academy of Sciences, has significant implications for understanding Mars’ past and whether it could have supported life.
The researchers believe these ancient beaches were formed by processes similar to those on Earth, such as waves and tides. The ocean, named Deuteronilus, is thought to have existed around 3.5 to four billion years ago, when Mars had a thicker atmosphere and a warmer climate. Shorelines, like those identified on Mars, are particularly interesting because they are prime locations for searching for evidence of past life. Planetary scientist Michael Manga, a co-author of the study, noted that shorelines on Earth are where some of the earliest life forms are believed to have emerged, near the interface of air and shallow water. This makes the discovery of Martian beaches a promising lead in the search for life beyond Earth.
The study also ruled out other explanations for the structures detected by the Zhurong rover. Benjamin Cardenas, a geoscientist at Penn State and co-author of the study, explained that the deposits were unlikely to be from ancient rivers or sand dunes. While dunes often form in groups with characteristic patterns, these deposits lacked such features. Similarly, the patterns observed did not match those typically left by rivers. “Beaches simply fit the observations the best,” Cardenas said. This conclusion adds credibility to the idea that Mars once had a coastline, complete with waves and tides shaping its surface.
The discovery of these ancient beaches is even more remarkable given the challenges of preserving such features over billions of years. Mars has been subjected to intense winds, meteorite strikes, and volcanic activity, all of which could erase or distort geological evidence. However, the deposits detected by the Zhurong rover were buried under layers of material deposited by dust storms and other geological processes, preserving them over time. This preservation is crucial, as it allows scientists to study these ancient structures in detail and gain insights into Mars’ past environment.
This finding is not the first to suggest that Mars once had liquid water on its surface. A study published last year found evidence of a large reservoir of liquid water beneath the Martian surface, trapped in fractured igneous rocks. While this reservoir could still exist today, any surface evidence of it would have been erased by geological activity over billions of years. In contrast, the structures identified in the recent study are direct evidence of ancient shorelines, offering a unique window into Mars’ watery past.
The implications of this discovery are profound, particularly in the context of the search for life on Mars. Shorelines on Earth are often teeming with life, as they provide a rich environment for organisms to thrive. If Mars once had similar environments, it raises the possibility that life may have existed there as well. While the Zhurong rover’s findings do not provide direct evidence of life on Mars, they do suggest that the planet may have had the conditions necessary to support it. This makes future studies of these ancient shorelines a critical step in unraveling the mysteries of Mars’ past and its potential for life.
