China's rover finds geometric shapes under Martian surface

China became the second country to land a rover on Mars with the successful landing of the Zhurong rover on May 15, 2021. The rover made important observations and studied the red planet as it moved around the surface. The rover was also equipped with a ground-penetrating radar (GPR) which could peer under the surface of the red planet.

Researchers have now announced that the rover found irregular polygonal wedges about 35 metres under the surface where it landed.

While it is quite tempting to imagine that these geometric polygons are remnants of some complex machinery developed by aliens on Mars, scientists think there are other reasons for their existence.

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The team of researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences writes in their paper in the journal Nature that Zhurong detected 16 such polygonal wedges within a stretch of 1.2 kilometres on Mars. These wedges measure from a few centimetres to tens of metres across. The research paper was cited by ScienceAlert in its report.

Freeze-thaw cycles and volcanic activity on Mars

Researchers believe that these wedges were formed due to freeze-thaw cycles on Mars billions of years ago. But the origin of these wedges can also be volcanic and they may also have formed from cooling lava flows.

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The researchers say that these polygonal structures may have been formed 3.7 – 2.9 billion years ago that is, Late Hesperian–Early Amazonian epochs on Mars. These were formed "possibly with the cessation of an ancient wet environment. The palaeo-polygonal terrain, either with or without being eroded, was subsequently buried," say researchers as quoted by SciencAlert.

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"The possible presence of water and ice required for the freeze–thaw 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," the paper explains.

"The subsurface structure with the covering materials overlying the buried palaeo-polygonal terrain suggests that there was a notable palaeoclimatic transformation some time thereafter," the researchers wrote.

(With inputs from agencies)