Three underground lakes were discovered near the South Pole of Mars using the radar of the automatic interplanetary station of the European Space Agency “Mars Express”. Earlier, in 2018, one such lake was already discovered there.
Since the presence of water is a key condition for the existence of life, its discovery on any cosmic body attracts special attention. However, as scientists suggest, the water in the Martian lakes is so salty that even the most persistent microbes will not survive in it.
Since the atmosphere of Mars is very rarefied, and temperatures are lower than in Antarctica, water cannot be in liquid form on its surface. The lakes are located at a depth of about one and a half kilometers under the polar cap consisting of ice and sand.
Since there, too, the temperature is kept well below the freezing point, the researchers explain the liquid state of the water by the high content of salts in it.
Experiments have shown that water saturated with magnesium salts and calcium perchlorate turns into ice at -123 degrees.
“These experiments have demonstrated that saline bodies of water can exist for entire geological periods, even at temperatures typical of the polar regions of Mars,” said study co-author Graziela Caprarelli of the University of South Queensland in Australia. “But the creation and maintenance of such underground lakes requires high salinity. “.
Viewed from orbit
The discovery was made using Marsis radar aboard the Mars Express orbital station, orbiting the Red Planet since December 2003.
The radar uses technology that is used to study sub-ice lakes in Antarctica, Greenland and Canada, adapted to the conditions of Mars.
“The most likely explanation for the available data is that reflections from the surface of Mars increase in intensity where there are vast reservoirs of fluid,” says Sebastian Lauro of the University of Tre in Rome.
In 2018, analyzing information from Marsis, researchers suggested the existence of an underground lake about 20 km long in the South Pole region.
This discovery was based on 29 measurements taken in 2012-2015. Now an international group of researchers, many of whom worked in 2018, additionally analyzed data from another 134 measurements for the period from 2010 to 2019.
“We not only confirmed the original discovery, but also found three more smaller lakes surrounding the main one,” says Elena Pettinelli of Tre University. “Due to the limited technical capabilities of the radar and its distance from the Martian surface, we cannot say with certainty whether whether they are between themselves or not.”
Traces of early life form
Whether any form of life can exist in lakes depends on the degree of their salinity. On Earth, in highly salty water bodies, only a special type of microbes, called halophiles, survive.
“The emergence of the only subglacial lake could be attributed to some exceptional circumstances, for example, the presence of a nearby volcano hidden under the ice cap. But the discovery of a whole system of lakes suggests that their formation is a relatively simple and widespread process, and that such lakes probably have existed for much of Mars’ history,” says Marsis Science Director Roberto Orosei.
“Therefore, they can retain traces of those forms of life that were on Mars, when there was a dense atmosphere, a warmer climate, water on the planet’s surface, and conditions resembled those that were on Earth in the early period,” the scientist said.
Exploration of the Red Planet continues. The details of the research results will be announced a little later.