A Chinese rover has found new evidence supporting the theory that Mars was once home to a vast ocean, including traces of an ancient coastline, according to a study published Thursday.
The theory that an ocean covered up to a third of the Red Planet billions of years ago has been a topic of debate among scientists for decades, and one outside researcher expressed some skepticism about the latest findings.
The Zhurong rover landed on Mars in 2021, on a plain in the Utopia region of the northern Martian hemisphere, where signs of water had previously been detected.
It has been exploring the surface of the red planet ever since, and some of the mission’s new findings were revealed in the study published in the journal Nature.
Bo Wu, lead author of the study from Hong Kong Polytechnic University, told AFP that Several clues suggest that there was an ocean in the area around the Zhurong landing area.
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Among these signs, “cones with holes, polygonal grooves and traces of flows.”
Previous research has suggested that the pitted, crater-like cones could have arisen from mud volcanoes, which often form in areas where water or ice once existed.
Data from the rover, as well as satellite data and analysis on Earth, also suggest a coastline (as far as the water reached), according to the study.
The research team estimated that The ocean was formed by floods approximately 3.7 billion years ago.
The ocean then froze, carving out a coastline, before disappearing about 3.4 billion years ago, they hypothesize.
Bo emphasized that the team “He does not claim that his findings definitively prove that there was an ocean on Mars.”.
That level of certainty will likely require a mission to bring some Martian rocks back to Earth for closer inspection.
The coast is always changing
Benjamin Cardenas, a scientist who has analyzed other theories about a Martian ocean, was “skeptical,” speaking to AFP.
In his opinion, Researchers did not sufficiently take into account the extent to which the strong Martian wind has moved sediments and worn away rocks. in the last billions of years.
“We tend to think of Mars as a not very active place, like the Moon, but it is active!” said Cardenas, of the University of Pennsylvania in the United States.
Cardenas recalled that previous research suggests that “even low rates of Martian erosion” would destroy signs of a coastline over such a long period.
Bo acknowledged that wind might have worn away some rocks, but noted that the impact of meteorites hitting Mars can also “excavate underground rocks and sediments to the surface from time to time.”
Although the overall theory remains controversial, Cardenas said he tends to “think there was an ocean on Mars.”
Discovering the truth could help unravel a bigger mystery: if the Earth is unique in the Solar System for its capacity to host life.
“Most scientists think that life on Earth arose either under the ocean, where hot gases and minerals from the subsurface reached the seafloor, or very close to the point of contact between water and air,” Cardenas explained.
“Possible evidence of an ocean makes the planet seem more hospitable,” he added.