Found coastline that could be ancient ocean on Mars

Data from China's Zhurong rover has revealed what appears to be an ancient coastline running across Mars' northern hemisphere.

Scientists studying data sent back by China's Zhurong probe say the findings provide new evidence for a decades-old theory that an ancient ocean covered northern Mars billions of years ago.

Since Zhurong landed in 2021 in one of the largest and oldest impact basins on Mars, called Utopia Planitia , the rover has traveled about 2 kilometers to study the surrounding geology in search of signs of water or ice.

A photo taken by China's Zhurong Mars rover during the Tianwen-1 mission. (Photo: China News Service).

Signs of water found on Mars

By combining observations from the rover's onboard cameras and ground-penetrating radar with remote sensing data from orbiting satellites, Bo Wu of the Hong Kong Polytechnic University and colleagues discovered a number of water-related features around the rover's landing site. These included crater-like cones, troughs, sedimentary channels and mud volcanoes that the team interpreted as evidence of an ancient coastline.

Based on the composition of surface sediments in the area, this ocean may have existed about 3.68 billion years ago, according to a paper describing the findings published in the journal Scientific Reports.

The presence of water, a key ingredient for life as we know it, and an ancient ocean on Mars suggest that Mars was once capable of harboring conditions favorable to microbial life. Scientists continue to piece together how all that water began to disappear into space about 3 billion years ago. Much of the escape is known to have been hastened by frequent solar storms from a young sun that stripped away Mars' thick atmosphere.

Scientists also think that at least part of the ocean must have disappeared underground. Data from NASA's Insight lander recently found that enough water to cover Mars with an ocean one to two kilometers deep has seeped into the planet's crust, where it is stored in tiny cracks and pores. Although Insight has not found any evidence of life on Mars.