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Scientists have found significant outflows in rivers for over a billion years – ScienceDaily

Long ago on Mars, water has carved deep riverbeds into the surface of the planet – but we still do not know what the weather was feeding them. The scientists are not sure because their understanding of the climate of Mars in the Martian world was still incomplete billions of years ago.

A recent study by scientists at the University of Chicago cataloged these rivers to conclude that a significant river drain on Mars has existed later in its history than previously thought. According to the study, published on March 27 Science Advances the outflow was intense – rivers on Mars were wider than today's on Earth – and were held at hundreds of locations on the red planet.

This complicates the picture for scientists who wanted to model the ancient Martian climate, said senior study author Edwin Kite, Assistant Professor of Geophysical Sciences and an expert on the history of Mars and the climate of other worlds. "It's difficult to explain rivers or lakes based on our information," he said. "This makes a difficult problem even more difficult."

But he said the constraints could be helpful to investigate the many theories that researchers have proposed to explain the climate.

Mars is criss-crossed with the characteristic traces of the long time. dead rivers. NASA spacecraft have photographed hundreds of these orbital flows, and when the Mars rover Curiosity landed in 201

2, it sent back images of rounded pebbles that had long fallen in a riverbed.

A mystery why ancient Mars had liquid water. Mars today has an extremely thin atmosphere, and at the beginning of planetary history, it also received only one-third of the sunlight of today's earth, which should not be enough heat to maintain liquid water. "Even on ancient Mars If it was at times wet enough for rivers, the rest of the data looks like Mars has been extremely cold and dry most of the time," Kite said.

Looking for a better understanding of the Martian precipitation, Kite and his colleagues analyzed photographs and elevation models for more than 200 ancient Marsland riverbeds spanning over a billion years. These riverbeds are a rich source of clues to the water that flows through them and the climate that created them. For example, the width and steepness of the river beds and the size of the gravel tell the scientists about the force of the water flow, and the amount of gravel limits the volume of water flowing through.

Your analysis shows clear evidence of consistency Kite said it was a strong runoff that went well into the final stages of humid climates.

The results give guidance to those trying to reconstruct the Martian climate, Kite said. For example, the size of the rivers indicates that the water is flowing continuously, not only at lunchtime. Therefore, climate modellers need to consider a strong greenhouse effect in order to keep the planet warm enough for the average daytime temperatures above the freezing point of the water. 19659003] The rivers also show strong currents until the last geological minute before the wet climate subsides. "They would expect to gradually fade over time, but we do not see that," Kite said. The rivers are getting shorter – hundreds of miles instead of thousands – but the discharge is still strong. "The wettest day of the year is still very wet."

Possibly the climate had a kind of "on / off" switch, speculated kite tipping between dry and wet cycles.

"Our work answers some existing questions but raises a new one: what is wrong: the climate models, the atmospheric evolution models, or our basic understanding of the inner solar system chronology?" He said

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