China's Zhurong rover finds evidence of water activity on Mars 750 million years ago

(ECNS) — Chinese scientists say data from the Zhurong Mars rover show signs of significant water-related activity on the planet's surface about 750 million years ago, far later than previously thought.

Researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences (CAS), together with collaborating institutions, analyzed high-frequency ground-penetrating radar data obtained by the rover. The study was recently published in the journal National Science Review.

For years, the prevailing view in the scientific community has been that Mars entered a largely dry and arid phase around 3 billion years ago. Given the planet's current cold and desiccated conditions, scientists have emphasized that traces of ancient water are more likely to be preserved underground rather than on the surface.

After landing in May 2021, Zhurong traveled approximately 1.9 kilometers across the southern part of the Utopia Planitia, using its high-frequency quadrupolar radar to conduct shallow subsurface investigations—effectively performing a detailed "CT scan" of the Martian ground.

The radar data revealed a widespread, uniform sedimentary layer about four meters thick beneath the landing site, with buried impact craters below. According to Liu Yike, the study's first and corresponding author and a researcher at the CAS Institute of Geology and Geophysics, the consistent thickness and continuity of this layer rule out volcanic eruptions or simple wind-driven deposition as possible explanations.

"The only reasonable interpretation is that the area was once shaped by water-related sedimentary processes, similar to those found in shallow seas or large lakes on Earth," Liu said.

In addition, the radar detected thinly layered centimeter-scale structures whose morphology closely resembles that of water-deposited sedimentary rocks observed on Earth. These features provide further evidence that the region once hosted a shallow aquatic environment.

By combining subsurface stratigraphy with crater dating techniques, the research team determined that the sedimentary layer formed around 750 million years ago, during the mid-to-late Amazonian period of Martian geological history.

(By Evelyn)