VOA科学技术2024--Study: Chinese Rover Finds Evidence of Ancient Ocean on Mars

（单词翻译）

Scientists say newly examined data from a Chinese explorer on Mars adds to existing evidence that the planet once had a very large ocean.

The exploring vehicle, or rover, is called Zhurong. It landed on the Martian surface in 2021. The rover has been operating in an area known as Utopia Planitia. This area is a large plain in Mars' northern hemisphere, the American space agency NASA explains.

The researchers combined data from Zhurong's instruments with observations from satellites and spacecraft orbiting Mars. The team said the examinations appeared to show that Utopia Planitia had geological elements suggesting an ancient ocean coastline.

The scientists said multiple elements, or features, pointed¹ to evidence that a large ocean existed on Mars billions of years ago. The discovered surface features included troughs and channels that may have been formed by flowing water on Mars.

Earlier research that examined data of similar surface features suggested they might have been created by mud volcanoes, which likely formed in areas where there had been water or ice.

The researchers said the evidence suggests the area likely contained deep ocean environments as well as shallow ones. The research findings were recently reported in a study in the publication Scientific Reports.

Bo Wu was the lead writer of the study. He is a planetary scientist at Hong Kong Polytechnic² University. Wu told Reuters news agency, "We estimate the flooding of the Utopia Planitia on Mars was approximately 3.68 billion years ago. The ocean surface was likely frozen in a geologically short period."

The search for water on Mars is closely linked to the search for signs of possible life. Evidence of a past ocean raises the possibility that the planet may have once supported microbial life.

There have been past studies suggesting Mars once had a large northern ocean. One such study was released in 2022. That research was based on satellite images of the Martian surface. The images were combined to produce detailed³ maps of the planet's northern hemisphere. Examination of the maps led to evidence of coastlines that once sat at the edge of a large ocean.

Another study, released in August, presented evidence suggesting Mars may contain a large ocean deep beneath its surface. That evidence was based on NASA's InSight Lander.

China's Zhurong rover began its data collection mission in May 2021. It stopped operating about one year later, with mission planners saying the power system was likely affected⁴ by sand and dust. But the rover still outlasted⁵ its planned mission of three months.

The researchers said the data shows that the ocean seems to have disappeared by about 3.42 billion years ago.

The study suggests the water that likely filled the Martian ocean was "heavily silted," study co-writer Sergey Krasilnikov said. He is a planetary scientist at Hong Kong Polytechnic University. Silt⁶ is a mix of sand and clay that has been carried by water, but later settles on land.

Krasilnikov added that during the period when the Martian ocean would have been active, the planet "...probably had a thick, warm atmosphere." At that time, "microbial life was much more likely," he said.

Hong Kong Polytechnic's Wu said the new findings do "provide further evidence to support the theory of a Martian ocean."

However, he told the French news agency AFP the study does "not claim that our findings definitively⁸ prove" there was an ocean on Mars. Such proof, he said, would likely require a future mission to bring Mars materials back to Earth for closer study.

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from Reuters, Agence France-Presse, Hong Kong Polytechnic University and Scientific Reports.

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Words in This Story

plain - n. a large area of flat land

trough - n. a low point in a series of high and low points

channel - n. a long, narrow passageway for water or other liquids to flow along

shallow - adj. not deep

definitive⁷ - adj. certain, clear and not likely to change