China\u2019s Zhurong rover was equipped with a ground-penetrating radar system, allowing it to peer beneath Mars\u2019s surface. Researchers have announced new results from the scans of Zhurong\u2019s landing site in Utopia Planitia, saying they identified irregular polygonal wedges located at a depth of about 35 meters all along the robot\u2019s journey. The objects measure from centimeters to tens of meters across. The scientists believe the buried polygons resulted from freeze-thaw cycles on Mars billions of years ago, but they could also be volcanic, from cooling lava flows.<\/p>\n
<\/p>\n The Zhurong rover landed on Mars on May 15, 2021, making China the second country ever to successfully land a rover on Mars. The cute rover, named after a Chinese god of fire, explored its landing site, sent back pictures \u2014 including a selfie with its lander, taken by a remote camera \u2013 studied the topography of Mars, and conducted measurements with its ground penetrating radar (GPR) instrument. Zhurong had a primary mission lifetime of three Earth months but it operated successfully for just over one Earth year before entering a planned hibernation. However, the rover has not been heard from since May of 2022.<\/p>\n Researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences who worked with Zhurong\u2019s data said the GPR provides an important complement to orbital radar explorations from missions such as ESA\u2019s Mars Express and China\u2019s own Tianwen-1 orbiter. They said in-situ GPR surveying can provide critical local details of shallow structures and composition within approximately 100-meter depths along the rover\u2019s traverse.<\/p>\n Utopia Planitia is a large plain within Utopia, the largest recognized impact basin on Mars (also in the Solar System) with an estimated diameter of 3,300 km. In total, the rover traveled 1,921 meters during its lifetime.<\/p>\n The researchers, led by Lei Zhang, wrote in their paper published in Nature, that the rover\u2019s radar detected sixteen polygonal wedges within about 1.2?kilometers distance, which suggests a wide distribution of similar terrain under Utopia Planitia. These detected features probably formed 3.7 \u2013 2.9 billion years ago during the Late Hesperian\u2013Early Amazonian epochs on Mars, \u201cpossibly with the cessation of an ancient wet environment. The palaeo-polygonal terrain, either with or without being eroded, was subsequently buried\u201d by later geological processes.<\/p>\n While polygon-type terrain has been seen across several areas of Mars from many previous missions, this is the first time there has been indications of buried polygon features. <\/p>\n The buried polygonal terrain requires a cold environment, the researchers wrote, that might be related to water\/ice freeze\u2013thaw processes in southern Utopia Planitia on early Mars.<\/p>\n \u201cThe possible presence of water and ice required for the freeze\u2013thaw process in the wedges may have come from cryogenic suction-induced moisture migration from an underground aquifer on Mars, snowfall from the air or vapor diffusion for pore ice deposition,\u201d the paper explains.<\/p>\n Earlier research from Zhurong\u2019s radar data indicated that multiple floods during that same time frame created several layers beneath the surface of Utopia Planitia.<\/p>\n While the new paper indicates that the most likely possible formation mechanisms would be soil contraction from wet sediments that dried, producing mud-cracks, however, contraction from cooling lava could have also produced thermal contraction cracking.<\/p>\n Either way, they note that a huge change in Mars\u2019 climate was responsible for the polygon\u2019s formation. <\/p>\n \u201cThe subsurface structure with the covering materials overlying the buried palaeo-polygonal terrain suggests that there was a notable palaeoclimatic transformation some time thereafter,\u201d the researchers said.<\/p>\n![\"\"](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2023\/11\/Utopia-Planetia.jpg\")
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