Liquid water may have existed extensively on Mars until 400,000 years ago, perhaps through melting snow on the dunes, according to new data from China’s Zhurong rover.
Our understanding of Mars has undergone some changes since the Zhurong rover landed on the Red Planet in early 2021. While we’ve known about the existence of ancient rivers and floods on Mars for decades, the last remaining liquids were thought to have dried up about three billion years ago. For comparison, this time period marks a period close to the time when the first single-celled organisms on Earth began to photosynthesize.
Only last year, however, these estimates began to change when the Zhurong rover discovered tentative evidence that liquid water may have been present on the planet as early as 700 million years ago.
Still, even estimates that varied at the time are almost insignificant compared to how far estimates of when potentially liquid water were found on Mars have now moved. Zhurong has spent the last few years surveying Utopia Planitia, a vast plain on the Martian surface that, at 3,300 kilometers wide, forms the largest impact basin in the solar system, collecting data on the composition of the windswept sand dunes that cover the land.
According to the Chinese Academy of Sciences team working on the mission, the information they found “provides critical clues for future exploration missions looking for signs of current life.” The scientists found that these dunes are covered with clumps of thin, cracked crusts and particles, and these features can only be explained by the presence of liquid water in the recent past, they say.
“The dunes are a more modern landform,” Xiaoguang Qin, a scientist at the Chinese Academy of Sciences and one of the authors of a new paper published on the findings, told New Scientist. ”
This new evidence suggests that instead of billions or hundreds of millions of years without liquid water, the Red Planet may have hosted pockets of frost or snow between 1.4 million and 400,000 years ago. This corresponds to an astonishingly new time period, a time when archaic humans were already roaming Europe.
May be possible with varying axis curvature
Qin notes that this is only possible due to Mars’ changing axial tilt. A few million years ago, the planet’s poles were more directly facing the sun, causing glaciers to release large amounts of water vapor that condensed as snow closer to the equator. Qin said in interviews with Space.com that “no water ice was detected by any instrument on the Zhurong rover,” but that this model still “offers a regeneration mechanism for atmospheric vapor to create frost or snow at low latitudes where the Zhurong rover has landed.”
While the possibility remains that these dunes were created by other unknown geological processes, other researchers report that the team’s suggestion is plausible. If this suggestion is correct, it would mean not only a massive re-creation of Mars’ geological timeline, but a reconsideration of its geography as well. Because sand dunes are so common all over the planet, there may be more modern evidence of water on Mars than previously known.
“The phenomenon has been documented somewhere,” Manasvi Lingam, a Florida Institute of Technology professor of astrobiology, who was not involved in the research, said in a conversation with Space.com.
The discovery has been published in detail in the journal Science Advances.
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