The first reported findings from China’s Mars rover suggest the plain it is exploring was shaped by winds – and perhaps also by water
China’s Zhurong Mars rover landed at Utopia Planitia – a large plain in the northern lowlands of the planet – back in May 2021. Now, initial data collected by the rover suggests that the site has been subject to long periods of weathering in the past by wind, and maybe even water.
During Zhurong’s first 60 sols (Mars-days) of operation, it traversed 450.9 metres of flat land littered with small rocks. At the same time, the rover collected data to study the planet’s geological structure and surface composition, which included taking soil and dust samples as well as capturing images with a camera called NaTeCam.
Liang Ding at the Harbin Institute of Technology in China and his colleagues analysed this initial data.
Many of the rocks that were found around the landing site were covered with etchings and grooves on one side, which indicates that they must have undergone intense wind erosion from sand. Some of the rocks also have a flaky texture, which typically arises from interactions with water, say the authors.
The rover also encountered several megaripples on the Martian surface – wind-sculpted features made up of loose sediment that span several metres.
“The examples Zhurong has visited appear very bright-toned in satellite images taken from orbit, and the team thinks that this is because the megaripples are covered with a layer of very fine dust,” says Matt Balme at the Open University, UK, who wasn’t involved in the analysis. “This means these features are probably currently inactive, as any present-day windblown sand would tend to remove the dust.”
Scientists got a first glimpse of Utopia Planitia’s rocks with NASA’s Viking 2 lander in 1976. At that time, they were widely interpreted as fragments of basaltic lava, says John Bridges at the University of Leicester, UK.
“However, the landing site rocks here don’t obviously look like basaltic lava terrain that we associate with the crust at Utopia Planitia,” says Bridges. “Zhurong is suggesting a more complicated geological evolution than expected from Viking 2.”
“From Viking 2, the paradigm was that Mars was a big lump of basalt with maybe a few flood channels,” says Bridges. But now the evidence from the rover supports a paradigm shift towards a sedimentary Mars, he says.
The soil samples taken at the site by Zhurong were found to have a similar composition to those collected by other rovers elsewhere on Mars.
Overall, these initial findings suggest that this site has the potential to provide more insight into the history of the planet’s surface.
“What’s really exciting is that many scientists think that Utopia Planitia may have once hosted an ancient liquid water ocean, billions of years ago,” says Joel Davis at the Natural History Museum in London. “Hopefully, as Zhurong continues to explore, it will be able to help answer this question [of whether there was an ocean] that’s been plaguing scientists for decades.”
Journal reference: Nature Geoscience, DOI: 10.1038/s41561-022-00905-6
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