Discovery of ancient riverbeds suggests Mars once wetter than thought | Mars

Thousands of kilometers of former rivers’ beds were discovered in the highly crushed highlands of March, suggesting that the red planet was once a much humid world than scientists thought.

The researchers spotted geological traces of nearly 10,000 miles (16,000 km) of former rivers, supposed to have more than 3 billion years, in high -resolution images of the accident landscape captured by Mars Orbiters.

Although some of the river beds are relatively short, others form networks that extend over more than 100 miles. The widespread rivers have probably been reconstructed by regular rains or snowfall in the region, researchers said.

“The water has been found on Mars countless times before, but what is really interesting here is that it is an area where for a long time, we thought there was no proof of water,” said Adam Lostkoot, a doctoral student at the open university. “What we found is that the area had water and it was very distributed,” he added. “The only source of water that could have supported these rivers in such a large area should be a kind of regional precipitation.”

The most dramatic signs of ancient water on Mars are the huge networks of valleys and canyons, which would have been sculpted by water flowing on the ground. But some regions of the planet have few valleys, which led scientists to wonder how wet the regions.

A region that particularly intrigued researchers was Noachis Terra, or Land of Noah, one of the oldest landscapes in March. According to computer models from the old Martian climate, the region should have had a substantial rain or snowfall, sculpting the ground while water was flowing.

Faced with a lack of evidence for the old river beds, Lostkoot and his colleagues have turned to high resolution images of Noachis Terra captured by instruments on Mars Recognition Orbiter (MRO) and Mars Global Surveyor of NASA. The images covered almost 4 square meters from the high lands in the south of the planet, a much larger land area than Australia.

The images have revealed geological characteristics called winding river crests, also called inverted channels. These are formed when traces of sediment transported by ancient rivers harden over time, and are later exposed when the soil softer around them. While some tracks are relatively narrow, others measure more than one mile wide.

“We have a lot of small crest segments, and they generally measure a few hundred meters wide and about 3.5 km long, but there are many, much larger than that,” said Losekoot.

In an image of the MRO, the motif of the winding river crests reveals a network of tributaries and winding spots where the ancient banks burst. Two rivers can be seen crossing a crater, where the water has probably sank and fills it before violating the other side.

The results, which will be presented Thursday at the national meeting of the Royal Astronomical Society in Durham, suggest a lasting presence of surface water in the Noachis Terra of Mars region about 3.7 billion years ago.

In its warmer and humid past, the planet contained large bodies of water. Mars has become the arid world that we know today when its magnetic field has decreased, allowing solar wind to erode its atmosphere and water escapes in space. But a certain water can remain, invisible. Beyond the Mars polar ice, an international team reported in April, a large water reservoir could be deeply hidden from the Martian surface.