Mars once had vast oceans with sandy beaches, new rover data reveals

Scientists have discovered evidence that Mars once had beaches with sand, suggesting the red planet previously had oceans, according to reporting from The Guardian which details how researchers analyzed below-ground imaging data from China's Zhurong rover to reach this conclusion.

The findings, published in the Proceedings of the National Academy of Sciences, show features in subsurface material that are tilted toward what would have been an ocean direction, similar to shorelines on Earth. According to Penn State University, Dr. Benjamin Cardenas, co-author, explains that the radar likely detected subtle changes in sediment size, indicating a beach that grew about 1.3 kilometers north into the ocean over time.

This ancient ocean would have featured rolling waves and sandy shores billions of years ago, as Forbes reports, highlighting that the Zhurong rover landed in Utopia Planitia, a vast lava plain long suspected to have once been underwater on Mars. Unlike previous NASA rovers, Zhurong carried ground-penetrating radar that could examine up to 260 feet beneath the surface, revealing thick, sloping layers consistent with "foreshore deposits" found in coastal regions on Earth.

According to Forbes, scientists have debated how Mars lost its water, with some believing it escaped into space while others think much remains trapped underground in ice or mineral formations. The findings also validate long-held speculation that an ocean once covered Mars's northern hemisphere, something suspected since the Viking missions in the 1970s.

The beach discovered by Zhurong was found about 33 feet beneath the current Martian surface, as Space reports, revealing that the red planet was not always the chilly desert we see today--approximately 4 billion years ago, Mars featured rivers, lakes and oceans with beaches. The rover's ground-penetrating radar measured thick layers of sand sloping gently upward toward what was once a rocky shore, preserved beneath layers of debris from asteroid impacts, volcanoes and dust storms.

According to Space, Zhurong spent a year exploring the base of a steeply-sloped rock outcrop at the edge of a flat plain, which appears to be inside Utopia Basin--the largest known crater in the solar system at 2,050 miles wide. Hai Liu, a professor at Guangzhou University and member of the Tianwen-1 mission science team, stated this discovery "strengthens the case for past habitability in this region on Mars," supporting the possibility that life could have developed in these shoreline environments.