Ground-penetrating radar data obtained by China's Zhurong rover has revealed evidence beneath the Martian surface that resembles sandy beaches from the shoreline of a large ocean that may have existed long ago on the northern plains of Mars.The findings add to the growing evidence suggesting the presence of an ancient ocean, called Deuteronilus, which is believed to have existed roughly 3.5 to 4 billion years ago. During that time, Mars had a thicker atmosphere and a warmer climate. Scientists speculate that such an ocean of liquid water could have provided conditions suitable for life, similar to early Earth's primordial seas.Operating from May 2021 to May 2022, the Zhurong rover traveled about 1.2 miles (1.9 km) in an area showing surface features suggestive of an ancient shoreline. Its ground-penetrating radar, which transmitted high-frequency radio waves into the ground and analyzed the reflected signals, probed up to 80 meters (260 feet) beneath the surface.Radar images detected layers of material, measuring 10-35 meters (33-115 feet) thick, with properties similar to sand. These layers were all sloped in the same direction at an angle resembling beaches found on Earth, just below the waterline where the sea meets the land. The researchers mapped these formations over a span of 1.2 km (three-quarters of a mile) along the rover's path.What Researchers SayOn Earth, beach deposits of this size would have taken millions of years to form. Researchers suggest that on Mars, a large and long-lasting body of water likely existed, with wave action distributing sediments carried in by rivers flowing from nearby highlands."The beaches would have been formed by similar processes to those on Earth—waves and tides," said Guangzhou University planetary scientist Hai Liu, a member of the Tianwen-1 mission's science team. "Such oceans would have profoundly influenced Mars' climate, shaped its landscape, and created environments potentially suitable for life to emerge and thrive.""Shorelines are great locations to look for evidence of past life," said planetary scientist and study co-author Michael Manga of the University of California, Berkeley. "It's thought that the earliest life on Earth began at locations like this, near the interface of air and shallow water."The rover explored the southern part of Utopia Planitia, a vast plain in Mars' northern hemisphere.The researchers ruled out other possible explanations for the structures Zhurong detected.
