The space agency Mars Express of the European Space Agency has received evidence of the presence of liquid water reserves under the layers of ice and dust in one of the regions of the South Pole of Mars. The official website of the European Space Agency writes about the discovery.
The fact that once there was liquid water on the surface of the Red Planet hints at geological features for a long time in the form of ancient dried up channels of rivers, canals and other geological structures visible from orbital vehicles. In addition, in tandem with orbital probes on the surface of the planet, several rovers operate, which also find evidence in favor of the “raw” history of the Red Planet. It is indicated at least by the presence of certain types of minerals that can be formed only in the presence of water pressure.
According to scientists, during the existence of Mars (about 4.6 billion years) its climate has changed significantly and today the water in liquid form is not can linger on the surface of the planet. Therefore, the researchers decided to see if there is any liquid water under it.
Planetologists have long been inclined to the possibility of the presence of liquid water under the base of ice caps at the poles. In the end, we know that the freezing point can be reduced by the pressure of the overlying glacier. In addition, the presence of salts on Mars can further reduce the freezing point by allowing water to be retained in the liquid state even at a negative temperature.
Until recently, data from the European Space Agency's specialized radar for probing the ionosphere and deep layers of the Martian surface (MARSIS) appeared to scientists unconvincing. In order to confirm their assumptions, researchers had to work hard on how to maximize its efficiency and enable it to collect data at such a high resolution, as far as it is possible in this case.
The penetrating radar uses the method of sending signals across the surface of the planet and calculates the time it takes to reflect the signal and return it to the spacecraft. The peculiarity of the chemical properties of the elements that are in the way of signal motion change it. The signal can be either dimmer, which can say, for example, about the presence of hard rocks in its path, or more distinct or even amplified, which will speak of the high reflectivity of the element that reflected it. Thanks to this, scientists can determine what is under the surface of the planet.
The map of the Southern Plateau and the area in which the studies were conducted
The probing of a region about 200 km wide with MARSIS showed that the surface of the South Pole of Mars is covered with several layers of ice and dust and a depth of about 1.5 kilometers. A particularly powerful increase in the reflection of the signal was recorded under layered sediments within a 20-kilometer zone at a depth of about 1.5 kilometers. After analyzing the properties of the reflected signal and studying the composition of the layered sediments, as well as the expected temperature profile below the surface of this region, the scientists concluded that MARSIS detected a pocket under the surface with a lake of liquid water. Scientists note that the device could not determine how deep the lake could be, but, according to rough estimates, its depth should be at least several dozen centimeters (this should be a layer of water to be seen by MARSIS).
Image from the MARSIS radar  “It really qualifies as a pond. The lake, and not some thawed water filling some space between the rock and ice, as it occurs in certain areas on Earth, “commented Professor Roberto Orosei of the Italian Institute of Astrophysics, who heads the study.
Theoretically, the amplification of the signal in which the lake is suspected can produce a layer of frozen carbon dioxide or simply water ice of low temperature, but the authors reject these assumptions, since these variants do not agree well enough with observational data.
“The only possible explanation for what we see is liquid water,” Orosei said.
“With the help of MARSIS, we found out that there is liquid water there, it is salty and in contact with bottom sediments. The ingredients for life to exist there, on the spot, and more MARSIS can not say anything, it can not answer the question of whether there is life there “, added Enrico Flamini, representing the Italian space agency.
” Assumptions about the presence of liquid water under the polar caps of Mars appeared many years ago. However, it has not been possible to confirm or deny them until now, and it was not possible to detect stable accumulations of liquid water on Mars, because the data collected were of very poor quality, “adds Andrea Cicchetti, co-author of the study.
A few percent Southern Plateau, and its characteristics allow us to see only large enough accumulations of water.
“This is only one small area. Just imagine that beneath the surface of Mars there can be many such underground lakes with water. “