A Chinese rover has discovered fresh evidence that Mars might have once had a huge ocean. A study released on Thursday shows that researchers found signs of an old coastline where water might have once reached.
For years, scientists have debated whether a third of Mars was covered in ocean billions of years ago, and some experts are unsure about this new evidence.
In 2021, China’s Zhurong rover landed in the Utopia region of Mars, where scientists had already found hints of ancient water. Since then, the rover has been exploring the red surface, and new details have emerged from its findings in a journal called Nature.
Bo Wu, the main author of the study from The Hong Kong Polytechnic University, said they found various features suggesting the past presence of an ocean, like “pitted cones, polygonal troughs, and etched flows.”
Previous studies indicated that these crater-like pitted cones may have resulted from mud volcanoes found in watery areas. The rover’s information, along with satellite data and Earth analysis, also suggested that a shoreline was previously near the landing site.
Researchers believe the ocean may have formed from a flood about 3.7 billion years ago, frozen over into a coastline, and then disappeared around 3.4 billion years ago. Bo pointed out that their findings don’t definitively prove Mars had an ocean—a conclusive answer would need samples of Martian rocks brought back to Earth.
Benjamin Cardenas, a researcher who has also studied Martian ocean evidence, had his doubts about the new results. He thinks the impact of strong Martian winds, which have moved sediment and worn down rocks over billions of years, might not have been fully considered.
He noted that while Mars might seem inactive, it does have activity that could erode evidence over time. Bo acknowledged the possibility of wind erosion but mentioned that meteor impacts can also bring underground materials to the surface.
While the idea of an ancient ocean on Mars is still debated, Cardenas leans towards believing it existed. Understanding this could help answer a bigger question: Is Earth the only planet in the Solar System capable of supporting life?
“Most scientists think life on Earth developed either in oceans, where hot gases and minerals came up from below, or in tidal pools,” Cardenas explained. “So, finding signs of an ocean makes Mars seem more welcoming for life.”
