China’s Zhurong rover may have discovered the coastline of an ancient ocean

Chinese scientists have discovered new confirmation of the long-standing hypothesis that billions of years ago the north of Mars was covered by an ocean. Traces of the ocean were found in data sent back by the Zhurong rover, and what’s more, scientists saw the outline of its coastline.

Mars rover “Zhuzhong”. Image source: China News Service

«Zhuzhong” landed on the Martian surface in 2021 – Utopia Plain was chosen for it. The device traveled 2 km, studying the geology of the surrounding area in search of signs of water or ice. By combining observations from the rover’s onboard cameras and ground penetrating radar with remote sensing data from orbiters, Hong Kong Polytechnic University professor Bo Wu and his colleagues discovered several water-related objects in the rover’s landing area. These are crater-shaped conical depressions, trenches, sedimentary channels and the formation of mud volcanoes – all of which, according to scientists, indicate that a coastline lay here.

After studying the composition of surface sediments in the area, the researchers said the ocean likely existed 3.68 billion years ago. During this time, various water-related minerals, including hydrated silica, began to form on the ocean floor. “The water was heavily silted, [due to which] a layered sediment structure was formed,” explained study co-author Sergey Krasilnikov. The ocean froze for 10,000 to 100,000 years, the coastline began to erode, and about 260 million years later it dried up. This scenario was questioned by Benjamin Cardenas, an associate professor at Pennsylvania State University, who argued that billions of years of erosion would have destroyed fragile shoreline features. Professor Wu agreed, but suggested that the shoreline features discovered by Zhurong had been raised by subsequent asteroid impacts.

The presence of water would mean that conditions favorable for the emergence of microorganisms may once have existed on Mars. Scientists are trying to understand why this water began to escape into space about 3 billion years ago. Perhaps the reason for this was the frequent solar storms of our young star, which destroyed the once dense Martian atmosphere.