Ancient Mars had planet-wide rainy seasons, so they broke its lakes

Billions of years ago, rain once fell on the Martian plain, and was not always soft.

New research on the now-empty lakes of the red planet suggests that 3.5 to 4 billion years ago there would have been a huge amount of liquid water flow from the sky, which would be enough to filter the rivers and drain many of the lake’s valleys. .

“This is extremely important because Mars was covered with water 3.5 to 4 billion years ago. There was a lot of rain or snowfall to fill those channels and lakes,” says planetary scientist Gaia Stucci de Coue of the University of Texas.

Looking at the climate of Mars in those years, it seems to be incredibly difficult, but studies on the geomorphology and chemistry of the planet certainly suggest that it was once home to an abundance of water Was, fed by both rain and snowfall.

Scientists are not sure how long this decline lasted, or whether the weather was torrential, a drizzle or a mixture, but traces on the surface of Mars suggest that there was once enough rainfall to leave a lasting impression.

“Now it’s completely dry,” Stunky de Quay says.

“We are trying to understand how much water was there and where it all went.”

Using satellite images and topography, researchers examined 96 lake valleys on Mars that are thought to have formed billions of years ago. Some basins were swept away by the flow of water, known as open basins, while others are intact, known as closed basins.

By measuring these lakes and their waterfields, the team was able to show how much rain and snowfall would be required to overflow open basins as well as fill intact basins without destroying them.

In cases where a closed and open basin was fed by the same river, researchers can estimate both the maximum and minimum rainfall that can fall in a single event.

In only one rainy season, which can last for several days or thousands of years, researchers estimate that rainfall on Mars falls somewhere between 4 and 159 meters (13 and 520 feet).

While the effect can be seen planet-wide, not all areas were affected equally. Some open-basin lakes were in areas that would be considered ‘semi-arid’ on Earth, so they probably received less water than the more humid parts.

“We again emphasize that our constraints are based on a range – not a cumulative – event (ie, lake overflow) that occurred during a single, semi-continuous runoff episode that may recur several times , ”The author writes.

“In fact, large erosion versions of inlet valleys require cumulative water volumes that typically exceed the volume of the lake basin, thus suggesting repeated runoff episodes …”

In other words, the deep channels run to the lakes were probably dropped at several places, which may have been swept into the lakes on several occasions.

Recently, however, some scientists have suggested that these valleys are not simply water-logged, and that by reducing the effects of rain, we can miss the rain ourselves.

Nevertheless, the authors think that these new insights may help with precipitation and aridity and help improve and test our climate model for the red planet, but they hold their conclusions that in the larger puzzle There is only one piece.

Understanding the climate evolution of Mars will be important to assess its potential to damage life, and this is why the Mars 2020 Persistence Rover is making its way to the lake bed right now.

The study was published in Geology.


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