The Zhurong rover discovers evidence of probable inundation billions of years ago on Mars

Region around the Zhurong rover landing site. a, Topographic map showing the landing site of Zhurong (red star), as well as the landing sites of the Phoenix, InSight, Curiosity, Perseverance and Viking-2 landers/rovers (orange squares). The purple solid and dashed lines show the locations of Martian palaeoshorelines of ref. 11, roughly delineating the depositional contact of the VBF in the northern plains. b, Simplified geological map near the Zhurong landing site with data from ref. 18. Scale bar, 200 km. c, Geomorphic map of the Zhurong landing area with data from ref. 22. Scale bar, 15 km. d, Traverse of the Zhurong rover from 25 May (Sol 11) to 6 September (Sol 113) 2021 on the basemap of a Tianwen-1 High Resolution Imaging Camera image (Sol 19, 2 June 2021). The red star marks the landing site (25.066° N, 109.925° E) and the red line shows the track of the rover. Scale bar, 100 m. Relative distances to the landing site are marked alongside the track. Credit: Nature (2022). DOI: 10.1038/s41586-022-05147-5

A team of Chinese Academy of Sciences researchers, collaborating with a colleague from Peking University, discovered evidence of a stratified subsurface in Mars' Utopian Basin. The group explains analyzing radar data from the Zhurong rover and what it revealed about the terrain under Mars' Utopia Planitia basin in a report published in the journal Nature.

In May 2021, China's National Space Administration will land the Zhurong rover on Mars. Since then, an impact crater has been rolling over the Utopia Planitia basin, examining the landscape and the stuff beneath it. The rover has gone roughly 1,171 meters to date. The rover is outfitted with ground-penetrating radar, which is continually fired at the ground while the rover moves, allowing the researchers to construct an underground map for depths ranging from 3 to 10 meters. The rover also contains a device capable of sending low-frequency radio waves into the ground at depths of up to 100 meters, albeit its resolution is significantly poorer than that of the radar.

The researchers discovered at least two layers of material beneath the basin, none of which is thought to contain water. One stratum was around 10 to 30 meters deep, while the other was about 30 to 80 meters down. Neither radar nor radio waves are capable of distinguishing between rock and ice or lava. As a result, the researchers have had to rely on ideas to explain the strata under the earth. They believe the deeper, older layer formed as smaller pebbles landed over larger boulders during a flood around 3 billion years ago.

The formation they discovered would need a rapid flood with adequate energy to transport huge boulders. The second layer, according to the researchers, might have formed in a similar way by a flood some 1.6 billion years ago. Prior study has revealed that there was a lot of glacial activity during that time period, they said. They also state that no evidence of volcanic activity that may have resulted in the formation of either stratum was discovered.

Journal Information: Chao Li et al, Layered subsurface in Utopia Basin of Mars revealed by Zhurong rover radar, Nature (2022). DOI: 10.1038/s41586-022-05147-5