Mars rover Zhurong finds the beach under the sand

Sun, sea, beach: in the past, Mars probably had an ocean with beaches like those we know from Earth. This is the result of an analysis of data collected by the Chinese Mars rover Zhurong.

The team led by Benjamin Cardenas, a geologist at Penn State University, has analyzed data from Zhurong. The Mars rover was the first to be equipped with ground-penetrating radar, which enables it to look deeper into the Earth. According to the researchers, the layers of rock examined beneath the surface of Mars strongly indicated that there was once an ocean there.

"We find places on Mars that look like former beaches and river deltas", said Cardenas. "We've found evidence of wind, waves and lots of sand – a real, vacation-ready beach."

Similarities to terrestrial coastal formations

In the comparison, the team found strong similarities with coastal formations on Earth, such as the so-called foreshore deposits that form when tides and waves deposit sediments. Such structures can also be found on beaches on Earth. This enabled the researchers to rule out other causes for these structures, such as wind, rivers or volcanoes.

"We can see that the coastline of this body of water has changed over time," said Cardenas. "We tend to think of Mars as a static snapshot of a planet, but it has evolved. Rivers flowed, sediments moved, land formed and eroded. This kind of sedimentary geology can tell us what the landscapes looked like, how they evolved and, importantly, help us figure out where to look for past life."

Life-friendly conditions

The new study, published by Cardenas' team in the journal Proceedings of the National Academy of Sciences, shows more clearly than before that water once existed in large quantities on Mars, as well as "a dynamic interface between air and water," Cardenas said. On Earth, life developed in the interaction between sea and land. Conditions would therefore have existed on Mars in which microbial life could have developed.

The 240-kilogram rover Zhurong (祝融), named after the Chinese god of fire, landed on Mars in May 2021, in the Utopia Planitia plain in the northern hemisphere. The primary mission ended after just three months. Nevertheless, the rover continued to be active and found evidence of liquid water – in early 2022, although this existed 700 million years ago. In May 2022, it was put into hibernation mode for the Martian winter and could not be reactivated afterwards.

(wpl)