Mars wasn’t always the frigid red dust ball that it is today.
Billions of years ago, hundreds of huge rivers of water flowed across the planet. In a new study, scientists said that those rivers – many wider than Earth’s rivers today – continued to flow around the Red Planet much later than previously thought.
The rivers likely flowed on Mars as far back as 3 billion years ago, just as the planet began to slowly dry out to its current arid climate. But the surprise from the new study was that the rivers only vanished for good relatively recently, less than 1 billion years ago.
In fact the rivers appeared to flow right up to the last geological minute before the wet climate dried up for good, said study lead author Edwin Kite, a University of Chicago geophysicist.
“You would expect them to wane gradually over time, but that’s not what we see,” he said. One reason, Kite speculated, was that the Martian climate may have had a sort of “on/off” switch, which tipped back and forth between dry and wet cycles.
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The findings were based on recent photos of the dried-up rivers taken by both ground-based robot rovers and by orbiting spacecraft.
The rivers there were quite large: Out of the 200 river channels found, the biggest river discovered was over a half-mile wide, “which is wider than the Mississippi at St. Louis,” Kite said to Newsweek.
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And even though this isn’t the first research into the history of Martian rivers, it does give scientists new details that “could lead to a better understanding of the planet’s climate history and life-hosting potential,” Space.com said.
Erin Kraal, a professor at Kutztown University of Pennsylvania who was not involved in the research, told Eos that the study reveals “another important and complex” clue of past climate.
Piecing together details about the ancient climate of Mars remains a puzzle for scientists, and this discovery only adds to the challenge: “It’s already hard to explain (Martian) rivers or lakes based on the information we have,” said Kite. “This makes a difficult problem even more difficult.”
The study appeared Wednesday in the peer-reviewed journal Science Advances, a publication of the American Association for the Advancement of Science.