At present, most of the water on Mars is blocked in frozen ice cream buckets. But billions of years circulated freely around the surface, forming currents of rivers that were emptied into craters, forming lakes and seas. A new investigation led by the University of Texas in Austin found evidence that sometimes the lakes were taking so much water that they overflowed and sank on the sides of their basins, creating catastrophic floods that were gunneling very quickly, perhaps in a matter of weeks.
The findings suggest that catastrophic geological processes can play an important role in shaping the landscape of Mars and other worlds without a tectonic plate, said lead author Tim Goudge, a postdoctoral researcher at the UT Jackson School of Geosciences, which will begin as an assistant professor at school at 2019.
"These breached lakes are quite common and some of them are quite large, some as big as the Caspian Sea," said Goudge. "So, we think that this flood-style of catastrophic overflow and rapid incision of exit cannons was probably quite important on the surface of Mars."
The research was published on November 16 in the magazine Geology. Co-authors include NASA scientist Caleb Fassett and professor at the Jackson School and Associate Dean of Research David Mohrig.
From the study of rock formations from satellite images, scientists know that hundreds of craters on the surface of Mars have been covered with water. More than 200 of these "paleolocas" have canyons of tens to tens of hundreds of kilometers in length and several kilometers in width carved by the water that flows from the old lakes.
However, up to this study, it is unknown whether the guns have been sculpted gradually for millions of years or quickly carved out of unusual floods.
Using high resolution photos taken by NASA's Mars Reconnaissance Orbiter, the researchers examined the topography of the crater tires and tires and found a correlation between the size of the output and the volume of water expected to launch during a major flood event. If the output had been gradually reduced over time, the relationship between the volume of water and the output size would probably not remain, said Goudge.
In total, the researchers examined 24 paleolakes and their exit cannons across the red planet. One of the pálulas examined in the study, Jezero Crater, is a potential landing spot for NASA's 2020 Mars rover mission to seek past life signs. Goudge and Fassett proposed the crater as a landing site based on previous studies that found it retained for long periods in the past of Mars.
While massive flooding that flows from Martian craters may sound like a scene in a science fiction novel, a similar process on Earth occurs when lakes packed by glaciers break their frostbite. The researchers found that the similarity is more than superficial. While gravity is counted, floods create exit points with similar forms, both on Earth and on Mars.
"This tells us that things that are different between planets are not as important as the basic physics of the overflowing process and the size of the bowl," said Goudge. "You can learn more about this process by comparing different planets compared to the simple reflection on what is happening on Earth or what is happening on Mars."
Although large flooding in Mars and Earth are governed by the same mechanics, they fit into different geological paradigms. On Earth, the slow and constant movement of tectonic plates dramatically changes the surface of the planet over millions of years. In contrast, the lack of tectonics of plate on Mars means that cataclysmic events, such as floods and impacts of asteroids, quickly create changes that can be placed near permanent changes in the landscape.
"The landscape on Earth does not preserve large lakes for a long time," said Fassett. "But on Mars … these guns have been there for 3,700 million years, a very long time, and give us an idea of what was the water from the bottom of the surface like on Mars."
The research was funded by a grant through NASA's Mars Data Analysis Program.
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