Zhurong rover's first radar imager results analysed two interesting underground layers
Fresh impact crater in Utopia Planitia in Mars. Photo: NASA / JPL-Caltech / University of Arizona
China’s Zhurong rover that landed on Mars in 2021 has found evidence of major floods that took place billions of years ago by studying underground layers.
The rover with ground-penetrating radar identified two horizontal layers underneath its landing site Utopia Planitia in the northern half of the Red Planet. These are the rover’s first results of the radar imager.
Liquid water was not found but each of these layers at depths of 10-80 metres had smaller rocks spread over larger ones, an analysis in the journal Nature showed.
The scientists think these may have been caused by flooding. The older, deeper and thicker layer that is between 30 and 80 metres underground was probably formed by rapid flooding three billion years ago, according to the report published September 27, 2022. “The upper layer (between 10 and 30 metres depth) could have been created by another flood some 1.6 billion years ago, when there was lots of glacial activity.”
Radio waves from the radar bounce off underground materials to reveal two crucial pieces of information about them: Their grain size and ability to hold an electric charge. “Stronger signals typically indicate larger objects.”
Previous Mars exploration missions also indicated that there was once water on the planet’s surface, as well as massive floods.
But some of the indicators may have also been caused by lava flow, and radar data is not enough to discern if the underground materials were sediments or volcanic remnants.
Radar data are good at indicating the layering and geometry of subsurface material, but not so good at pinpointing its composition, including whether the material is ice or rock, said Svein-Erik Hamran, a planetary scientist at the University of Oslo.
The rover is China’s first mission to Mars and more results are expected to emerge, according to the report.
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