Traces of water on the surface of Mars, found in recent years by NASA satellites, arose due to the melting of ice on the edges of large Martian craters after the fall of meteorites, according to an article published in the journal Geophysical Research Letters.
“If these valleys arose as a result of the release of groundwater to the surface of Mars, traces of water would be present in the very crater, but they are not there.” Given where the ice reserves were at that time and the amount of thawed water that should have occurred after The incidence of incandescent rocks on them, we believe that the valleys were formed in this way, “- says David Weiss (David Weiss) of Brown University (USA).
Recently, scientists have found many hints that on Mars in ancient times there were rivers, lakes and entire oceans, comparable to our Arctic. On the other hand, some planetary scientists believe that even then Mars was too cold to permanently have oceans on it, and the water could be in a liquid state only during the eruption of volcanoes or the fall of meteorites.
Recently, these ideas have been shaken – planetologists have found on the photographs of some of the Martian craters – like the equator (Istok and Jezero) and in the northern polar latitudes (Lio) – traces of water flows, which more recently, several dozens or hundreds of millions of years ago, Surface of Mars.
This discovery led many scientists to wonder how liquid water got to Mars and how it could have survived long enough to form a network of shallow but branched channels on the crater slopes. Many scientists suggest that in the recent past, the climate of Mars was much warmer and softer, therefore the underground ice reserves in the most sunlit areas of the planet could periodically melt and come to the surface after the fall of meteorites.
Weiss and his colleagues believe that this is not so. To this conclusion they came, for example, by examining the structure of the valleys on the edges of the Lyo crater from the images obtained by the MRO probe. This crater is a giant hollow with a diameter of 225 kilometers and a depth of about seven kilometers, which arose as a result of the fall of a large asteroid from 1.6 billion to three billion years ago.
The edges of this crater are covered with original rivers that flowed, according to Weiss and his colleagues, about 1.2-1.8 billion years ago. Studying the arrangement of channels, the scientists drew attention to the fact that they are all concentrated only on the north side of the crater and do not enter the funnel, which contradicted the idea of the primordial origin of such rivers and valleys.
The answer to the riddle, as these rivers arose, scientists found, studying the circumstances of the birth of the crater Lio. Weiss’s team noticed that all the channels and valleys of the “freshest” rivers are located where the melted fragments of soil and rocks that were thrown out when the asteroid collided with the surface of Mars were to fall.
As the calculations of geologists have shown, this heat should be enough to melt the significant reserves of ice under the surface of Mars and get enough water that can pierce these channels. Similarly, scientists believe, other traces of water could form in the southern regions of Mars, including those that are considered traces of a wetter and warmer era in the life of the red planet. This brings back to the idea that Mars could always be cold, scientists conclude.