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Evidence is increasingly indicating that Mars, now frigid and arid, had liquid water flowing across its surface much more recently than previously believed. Scientists have long maintained that Mars was wet approximately 3 billion years ago during the planet’s Hesperian epoch, before it lost most of its water. However, a recent study offers evidence of water activity dating back to just 700 million years ago, well into the current Amazonian epoch, presenting a new enigma to unravel regarding the Red Planet's history.
This novel study draws on data collected by China’s Zhurong rover, part of the Tianwen-1 mission that landed on Mars in May 2021. Specifically, the scientists utilized information gathered by the rover in its initial 92 Martian days, or sols, at its landing locale in Utopia Planitia. Yang Liu, a researcher at the National Space Science Center (NSSC) under the Chinese Academy of Sciences (CAS), along with colleagues, evaluated data from three distinct instruments on Zhurong: the laser-induced breakdown spectrometer, the telescopic microimaging camera, and the short-wave infrared spectrometer.
These instruments examined minerals that imply the existence of a considerable amount of liquid water at the site approximately 700 million years ago, a time when scientists previously assumed it was desiccated. “This is a remarkably intriguing finding,” comments Eva Scheller, a planetary scientist at the California Institute of Technology who was not part of the recent study.
“We possess very scant documented evidence of 'young' liquid water systems on Mars. And for the ones we have documented, they typically manifest as salt minerals.” However, Zhurong’s instruments detected water molecules embedded in the rock, “which is quite fascinating and distinguishes it from other observed young liquid water settings,” Scheller elucidated. “It suggests that specific types of water-containing minerals could have formed at much later periods than what was previously considered in other academic studies.”
So far, NASA has dispatched its Mars rovers to ancient landing locations dating back to the Noachian period, over 3.7 billion years ago. Zhurong is not merely an additional set of wheels on Mars, but a powerful ensemble of instruments investigating a new, geologically recent site, providing new avenues for research on Mars. “One of the primary aspects we will need to discover, and that I eagerly anticipate from the Zhurong rover, is the extent of these 'young' water-bearing minerals,” Scheller added.
“Are they common or rare in these 'young' rocks?” Zhurong has traversed about two kilometers (1.24 miles) during its over 350 Martian days, analyzing a variety of features throughout its journey, indicating that more novel insights about Mars are likely forthcoming from the rover.
--Bhautik Thummar
