November 23 2023, the Chinese National Space Administration reported that its Mars rover, Zhurong, had discovered polygonal terrain under the surface of the Red Planet.
On July 23 2020, China launched its Mars rover, Zhurong, into space and the Rover landed on Utopia Planitia in the northern martian hemisphere, the largest impact basin on Mars. The rover’s soft landing made China the second country to successfully land a rover on Mars.
Zhurong, equipped with a 19 – 95 MHz (low-frequency channel) and 450 – 2000 MHz (high-frequency) ground penetrating radar (GPR), was able to peer 35 meters under Mars’ surface to discover polygonal terrain. The 16 polygons discovered thus far in three quarters of a square mile are about 70 meters across, bordered by 30 meter wide wedges and dozens of meters deep. That’s ten times the size of Earth’s ice-wedge polygons. The polygons are believed to be around 2.9 to 3.7 billion years old, formed from sandy martian soil and ice during the Late Hesperian – Early Amazonian martian epochs.
These patterns, so similar to the Earth’s own at the poles, suggest that both were formed by similar processes. Freeze-thaw weathering. Water, at low temperatures, froze and expanded, then melted away to leave behind a web of cracks. Two shocking discoveries resulted from this one discovery.
First, it addresses the questions about Mars’ missing water. For these polygons to exist, there had to have been water on Mars. A report by a team of scientists from the Institute of Geology and Geophysics in the Chinese Academy of Sciences, published by Nature, explains that, “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.”
Second, the polygons were formed at the dry Martian equator, where the formation of such structures would not be possible under current, dry and arid conditions. “Forming polygons near the Martian equator wouldn’t be possible today”, says study co author Ross Mitchell, a geoscientist at the Institute of Geology and Geophysics in the CAS. “To form polygons, the region must have been colder and wetter in the past, much like a polar region.” Well, simulations of Mars’ orbit have yielded interesting results. Mars’ axis was once so tilted that the Red Planet veritably lay on its side. Such an axis would put the poles in the direct path of the sun’s light, and the equator would have been where the poles should be, forming the perfect conditions under which to form these polygons.
These are very interesting discoveries. They suggest that Mars might or might have been home to ancient life. The Utopia Planitia is an impressive record of the changes in Mars’ palaeoclimate, and the polygons imply that it varied dramatically. The Red Planet might have had both water and life. “We think of every planet other than Earth as dead,” Ross Mitchell says. “But if Mars’s axis does swing around often, our neighboring planet’s climate would be far more dynamic than currently believed.” Is the fourth planet from the sun where our search for extraterrestrial life finally yields fruit? Maybe. The world is still waiting.
