Evidence of an ancient ocean on Mars has potentially been uncovered by China’s Zhurong rover, scientists report. Data collected by the now-defunct rover indicates possible ancient coastlines in the northern hemisphere of Mars. Researchers at Hong Kong Polytechnic University, including lead scientist Bo Wu, believe the findings support long-standing theories of a large Martian ocean that existed billions of years ago. The Zhurong rover, which traveled about 2 kilometers within the Utopia Planitia basin, relayed this data through observations from its onboard cameras and ground-penetrating radar.
The study describing the findings was published in the journal Scientific Reports. Through exploration of Zhurong, researchers identified features possibly related to water activity, including structures such as crater cones, channels, and mud volcanoes. Scientists suggest that such structures may represent an ocean-shaped coastal landscape that once existed. Further analysis of surface deposits indicates that the ocean may have existed about 3.68 billion years ago, potentially containing silt-rich water that left distinct geological layers on the Martian landscape.
The complex history of water on Mars
The research team believes that Mars’ ancient ocean may have experienced phases of freezing and thawing, contributing to the formation of the observed coastline. Sergei Krasilnikov of Hong Kong Polytechnic University said the sea would have remained frozen for about 10,000 to 100,000 years before drying up completely, about 260 million years later. Wu acknowledged the difficulty in conclusively determining the shoreline due to erosion over millennia but proposed that some areas of the shoreline could have been preserved by asteroid impacts.
Future prospects for verifying Mars’ water history
Despite Zhurong’s findings, scientists acknowledge that definitive proof of Mars’ ancient water history will require analysis of Martian samples on Earth. China’s Tianwen 3 mission, scheduled to launch in 2028, aims to return surface samples by 2031. In comparison, NASA’s Mars Sample Return Mission is projected to return samples in the 2030s.
