Scientists have announced the discovery of three lakes buried near the south pole of Mars.
Scientists confirmed that there is a fourth lake, the existence of which was hinted at in 2018.
And since liquid water is vital to biology, the discovery will be of interest to researchers studying the possibility of life on another planet in the solar system.
But the lakes are also thought to be so salty, which could make any microbial life on the planet extremely difficult.
The thin Martian atmosphere means that liquid water is nearly impossible to have on the surface. But water can still be liquid underground.
Scientists made this latest discovery using data from a radar device on the Mars Express spacecraft of the European Space Agency (ESA), which has been orbiting the red planet since December 2003.
And in 2018, researchers used data from Marcyss radar to report signs of a sub-surface lake 20 km wide and 1.5 km below the planet’s south pole layers, a thick polar covering made up of layers of ice and dust.
However, this finding was based on 29 observations that Marcis compiled between 2012 and 2015. Currently, a team that includes several scientists who participated in the 2018 study has analyzed a much larger dataset of 134 files collected by radar between 2010 and 2019.
“Not only did we confirm the location, range and power of the inverter from our 2018 study, but we found three new illuminating areas,” said co-researcher Elena Bettinelli from the University of Rome Tree in Italy.
“The main lake is surrounded by small bodies of liquid water, but due to the technical characteristics of the radar, and its distance from the surface of Mars, we cannot determine whether it is conclusively connected,” she added.
The team borrowed a technique commonly used in radar investigations of subglacial lakes in Antarctica, Canada, and Greenland, to adapt the method for analyzing data from Marcis.
“The best explanation that matches all the available evidence is that high-intensity reflections (from Mars) come from extended pools of liquid water,” said co-author Sebastian Lauro of the University of Rome.
Since there is not enough heat in these depths of the planet to melt the ice, so scientists believe that liquid water should contain high concentrations of dissolved salts. So these chemical salts (which are different from the salt we use) can drastically lower the freezing point of water.
In fact, recent experiments have shown that water containing dissolved salts of magnesium and calcium perchlorate (a chemical compound containing chlorine bound to four oxygen atoms), can remain liquid at temperatures up to minus 123 degrees Celsius.
“These experiments showed that brine solutions can remain liquid for large geological periods of time even at temperatures typical of the Martian polar regions (well below the freezing temperature of pure water),” said co-researcher Graziela Cabrelli from the University of Southern Queensland in Australia.
“Therefore, we believe that any process of formation and continuation of glacial waters under the polar ice caps requires that the liquid have a high salinity,” she added.
The survival of life in such conditions depends on the salinity of the discovered Martian pools. On Earth, however, only very specific types of microbes, known as halophiles, can survive in the most salty bodies of water.
“While the existence of a single semi-glacial lake can be attributed to exceptional conditions such as the existence of a volcano under the ice sheet, the discovery of an entire system of lakes implies that their formation process is relatively simple and common, and that these lakes are relatively simple and common,” said Roberto Urosi, chief scientist for the Marcis experiment. It may have been around since ancient times on Mars.
“For this reason, they can still preserve traces of any life forms that might have evolved when Mars had a dense atmosphere, a milder climate and liquid water on the surface, similar to Earth in its early stages,” he added.