The surface of Mars' largest impact basin has been altered by weather and ancient water, according to China's first Mars rover.

A new study based on data from Zhurong's first 60 sols on the planet (roughly 62 Earth days) reveals how weather and water interaction changed the rocks around Zhurong's landing site over millions of years.

In May 2021, China's Zhurong rover touched down in the Utopia Planitia, a 2,000-mile-wide (3,300-kilometer) basin in Mars' Northern Hemisphere. Since then, the rover has been using its six scientific instruments to investigate local geology, rock chemical composition, and weather conditions.

A team of researchers led by Liang Ding of the Harbin Institute of Technology in Northeast China examined the structure of the rocks using images from the rover's Navigation and Topography Cameras (NaTeCam). The researchers discovered grooves and etchings from particles carried by wind, as well as flakes that appear to be evidence of interactions with water or brines, in many of the rocks studied.

"The rock textures observed at the site thus far may indicate both the presence of physical weathering - for example, impact sputtering, wind erosion and potential freeze-thaw weathering - and aqueous interactions involving salt and brine," the authors said in the paper, adding that the site offers opportunities for follow-up investigations.

"These rock and soil targets provide excellent opportunities to peek into the aqueous history and climate evolution of the northern lowlands, and shed light on the habitability evolution of Mars."

Chemistry data could provide more insight into what has been going on in the area. Zhurong has a Laser Induced Breakdown Spectroscopy (LIBS) instrument that can use its laser to create a small amount of plasma and analyze its composition. The new paper makes no mention of LIBS data or whether it was gathered from rock specimens.

In 1976, NASA's Viking 2 lander landed among numerous rocks in northern Utopia Planitia, whereas Zhurong is operating in far less difficult terrain.

Zhurong has already completed 90 sols of its primary mission. The rover, on the other hand, is continuing its journey south of its landing site, collecting data along the way.

Meanwhile, on Feb. 10, the Tianwen 1 orbiter, which carried Zhurong from Earth to Mars, celebrated its first anniversary in orbit around the Red Planet. The orbiter began its dedicated science mission in November, as well as assisting in the relay of data from the rover back to Earth.

China is planning a Mars sample return mission that could launch in 2028, but no information on potential landing sites has been released.
The paper was published in the journal Nature Geoscience.