Chinese Mars rover finds signs of recent water in sand dunes

CAPE CANAVERAL, Fla. (AP) — Water may be more widespread and recent on Mars than previously thought, based on observations of Martian sand dunes by the Chinese rover.

The discovery highlights potentially fertile new areas in the warmer regions of Mars, where conditions could be suitable for life to exist, although further study is needed.

Friday’s news comes just days after mission leaders acknowledged that the Zhurong rover has yet to wake up since it went into Martian winter hibernation nearly a year ago.

Its solar arrays are likely covered in dust, which cuts off its power source and possibly prevents the rover from working again, said Zhang Rongqiao, the mission’s lead designer.

Before Zhurong fell silent, he observed salt-rich dunes with cracks and crusts, which the researchers say were likely mixed with melting morning frost or snow until a few hundred thousand years ago.

Their estimated date range for when cracks and other dune features formed on Mars’ Utopia Planitia, a vast plain in the Northern Hemisphere: between 1.4 million and 400,000 years ago or earlier.

Conditions at that time were similar to today’s Mars, with rivers and lakes dried up and no longer flowing as they did billions of years ago.

Studying the structure and chemical composition of these dunes may provide insight into the “possibility of water activity” during this period, the Beijing-based team wrote in a study published in Science Advances.

“We think it could be a small amount … no more than a film of water on the surface,” co-author Xiaoguang Qin of the Institute of Geology and Geophysics said in an email.

The rover did not directly detect water in the form of frost or ice. Ma Qin said computer simulations and observations from other spacecraft on Mars indicate that even today at certain times of the year, conditions may be suitable for water to appear.

What’s notable about the study is how young the dunes are, said planetary scientist Frederic Schmidt of the University of Paris-Saclay, who was not involved in the study.

“This is clearly a new piece of science for this region,” he said in an email.

Small pockets of water from thawing frost or snow mixed with the salt likely resulted in small cracks, hard crusty surfaces, loose particles and other dune features such as depressions and ridges, Chinese scientists said. They ruled out wind as the cause, as well as frost made of carbon dioxide, which makes up most of Mars’ atmosphere.

Martian freezing has been observed since NASA’s Viking missions in the 1970s, but these light dustings of morning frost were thought to occur in certain locations under specific conditions.

The rover has now provided “evidence that there may be a wider distribution of this process on Mars than previously identified,” said Mary Bourke of Trinity College Dublin, an expert on Mars geology.

As small as this watery niche, it could be important for identifying habitable environments, he added.

Launched in 2020, the six-wheeled Zhurong, named after a fire god in Chinese mythology, arrived on Mars in 2021 and spent a year on the road before going dormant last May. The rover operated longer than expected, traveling more than a mile (1,921 meters).


AP video producer Olivia Zhang in Beijing contributed to this report.


The Associated Press Health and Science Department receives support from the Science and Educational Media Group of the Howard Hughes Medical Institute. The AP is solely responsible for all content.

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