China’s Zhurong Mars rover has uncovered compelling evidence of a vast, ancient ocean on Mars, a discovery that points to a time when the Red Planet was marked by substantial bodies of water. The findings, published in Scientific Reports, reveal that Zhurong’s landing site in Mars’ southern Utopia Planitia region may once have been a coastal area, representing remnants of a sea that existed during Mars’ early history.

Ancient shoreline discovered in Utopia Planitia – Mars

The Zhurong rover, which has been exploring the Planet since May 2021, detected signs of what scientists believe was an ancient coastline in Vastitas Borealis, a lowland plain in the planet’s northern hemisphere.

Research indicates this region likely harbored a sizable ocean in Mars’ past. According to the study, minerals such as hydrated silica—common in water-rich environments—were found in fine-grained deposits in the area, suggesting a marine rather than volcanic origin.

Key geological features support ocean theory

Lead study author Bo Wu from The Hong Kong Polytechnic University noted that several geological features near Zhurong’s landing site point to the presence of a former ocean. “Pitted cones, polygonal troughs, and etched flows” in the area resemble formations created by water or ice activity, Wu explained in a statement to AFP. Past research suggests that pitted cones in particular may have formed from mud volcanoes, a process typically associated with water or ice.

Supporting data and analysis

The research team combined data from both the Zhurong rover and NASA’s Mars Reconnaissance Orbiter, along with analysis conducted on Earth, to estimate surface ages and mineral compositions in the southern Utopia Planitia region. The results suggest a possible flood event around 3.7 billion years ago that created nearshore features, including troughs and sediment channels, in this area of Mars. “Our comprehensive geomorphological analysis, enhanced by remote sensing and in situ observations, unveiled features consistent with a nearshore zone in southern Utopia,” the researchers explained.

Caution: No direct evidence of water yet on Mars

While the findings are compelling, scientists caution that Zhurong’s data does not provide direct evidence of a former ocean. The rover’s observations offer indirect insights, revealing geological features consistent with a shoreline. For now, scientists consider these findings a significant step in understanding Mars’ aquatic past, while future missions may provide more definitive proof of ancient oceans on Mars.