Context: 

Ground-penetrating radar data from China's Zhurong rover has revealed evidence of buried features on Mars that resemble sandy beaches, suggesting the existence of an ancient ocean on the Martian northern plains. 

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• The study detailing the findings was published in the Proceedings of the National Academy of Sciences and highlights the role of Mars’s ancient shorelines in understanding the planet's potential for life.
• The discovery was made in the southern part of Utopia Planitia, a vast plain in Mars's northern hemisphere, which is known for its ancient surface features. 

Key Findings of the Study

The radar detected thick layers of sandy material buried between 33-115 feet (10-35 meters) beneath the surface. 

• These layers were sloped in the same direction and at an angle similar to Earth’s beach shorelines.

The findings support the hypothesis of a vast ocean, named Deuteronilus, that existed on Mars 3.5 to 4 billion years ago when Mars had a warmer climate and a thicker atmosphere.

• The research indicates that the ocean was large and long-lasting, capable of supporting such extensive beach formations over millions of years.

According to researchers, this large ocean on Mars could have created conditions suitable for the emergence of life, similar to the early primordial seas on Earth.

The beach-like structures are well-preserved under layers of Martian dust (formed by meteorite impacts and volcanic activity).

Other similar Hypotheses and studies

Since the solar system was formed roughly 4.5 billion years ago, the Deuteronilus would have disappeared approximately a billion years after the formation of Mars.

While some of the water may have been lost to space, large amounts may remain trapped underground. 

• This was corroborated by a study published last year based on seismic data obtained by NASA's robotic InSight lander which confirmed the possibility of a vast liquid water reservoir deep beneath Mars' surface, within fractured igneous rocks.  

About Zhurong rover

It was a part of the Tianwen-1 mission, which landed in the southern part of Utopia Planitia on May 15, 2021. 

It had a nominal expected lifetime of 90 sols (93 Earth days). However, it wildly exceeded its intended lifespan and was active for more than 347 sols (358 days).

• A "sol" is the term used to describe a single day on Mars, which is slightly longer (approximately 40 minutes) than an Earth day. 

The data provided by the rover is from May 2021 to May 2022.

Rover travelled approximately 1.2 miles (1.9 km) and used ground-penetrating radar to probe the Martian surface up to a depth of 80 meters (260 feet)