China's fully robotic rover on Mars has, for the first time, found traces of recent water activity on the Red Planet, indicating that Mars has a few areas where conditions are suitable for life to exist. According to a paper published in the journal Science Advances, the Zhurong rover, which landed on Mars in 2021, detected evidence of liquid water on sand dunes at low latitudes, i.e., towards the equator and away from its poles.

In their study, Chinese researchers noted that scientists have for long believed that Mars once had an earth-like climate and an ocean flowing across its surface about three billion years ago. But dramatic climate changes froze much, with scientist believing most of it likely became trapped in the planet's outer layer, or crust. To date, no evidence had provided to show the presence of liquid water at low latitudes on the Red Planet.

However, the latest research is now believed to be a major breakthrough in understanding the evolutionary history of Mars.

Scientists studying data from China's Zhurong rover pointed out that the rover did not directly detect any water in the form of frost or ice, rather it observed salt-rich dunes with cracks and crusts. The rover found cracked layers on tiny Martian dunes for the first time, which implies the Red Planet was a salt-rich watery world as recently as 400,000 years ago, the study said.

The Chinese researchers explained that since temperatures on Mars oscillate wildly and spike in the mornings, the saltwater evaporated and left behind salt and other newly formed minerals that later seeped between the dune's sand grains, cementing them to form a crust.

"This is important for understanding the evolutionary history of the Martian climate, looking for a habitable environment, and providing key clues for the future search for life," said lead researcher Professor Qin Xiaoguang, of the Chinese Academy of Sciences (CAS).

The team stated that they used data obtained by the robotic rover's Navigation and Terrain Camera, Multispectral Camera, and Mars Surface Composition Detector. They found that the surface layer of the dune was rich in hydrated sulfates, hydrated silica, iron oxide minerals and possibly chlorides.

"According to the measured meteorological data by Zhurong and other Mars rovers, we inferred that these dune surface characteristics were related to the involvement of liquid saline water formed by the subsequent melting of frost/snow falling on the salt-containing dune surfaces when cooling occurs," Mr Qin said.