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We can say that Mars is a desolate and dusty desert – but that's not always the case.
Billions of years ago, the planet was flooded with water and subjected to "catastrophic floods" that shaped the canyons of the landscape that still exist.
The floods came from gigantic lakes that were overflowing with water. Now these lakes are nothing more than enormous craters springing from the Martian surface.
"These lacerated lakes are quite common and some of them are quite big, some as big as the Caspian Sea," said Tim Goudge, a postdoctoral fellow at the Jackson School of Geosciences at the University of Texas.
"So we think that this type of catastrophic flood by overflow and rapid incision of exit canyons was probably very important on the surface of early Mars."
Goudge, along with Caleb Fassett, NASA scientist, and David Mohrig, professor at the School School and associate dean of research, co-authored an article on floods published in the journal Geology after analyzing images of Mars from NASA.
Until this study, it was not known if the canyons on Mars had been carved gradually over millions of years or quickly by unique floods.
Using high-resolution photos taken by NASA's Mars Reconnaissance Orbiter satellite, researchers examined the topography of the crater's outflows and edges and found a correlation between the size of the outlet and the volume of the crater. Water likely to be released during a large-scale flood.
If the output had been progressively reduced over time, the relationship between water volume and the size of the outlet would probably not be maintained, Goudge said.
In total, researchers examined 24 of these "paleolakes" and their exit canyons across the red planet.
The Jezero crater, one of the paleolakes analyzed in the study, is a potential landing site for NASA's search mission, looking for signs of past life. Goudge and Fassett proposed the crater as a landing site, based on previous studies, that he had held back water for long periods in Mars's past.
While massive floods from Martian craters may seem like a scene in a science fiction novel, a similar process occurs on Earth as glacially barred lakes cross ice barriers.
The researchers found that the similarity is more than superficial. As long as gravity is taken into account, floods create similarly shaped outlets, either on Earth or on Mars.
"This tells us that the differences between the planets are not as important as the basic physics of the overflow process and the size of the basin," said Goudge.
"You can learn more about this process by comparing different planets, instead of just thinking about what's happening on Earth or what's happening on Mars."
Caleb Fassett, NASA, said, "The landscape of the Earth does not conserve large lakes for a very long time. But on Mars, these canyons have existed for 3.7 billion years, a very long time, and this gives us an idea of what the surface water of the depths on Mars looked like. '
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