Scientists find underground lakes in the coldest regions of Mars

New radar signals taken in Antarctica from Mars indicates the presence ofunderground lakes, but many of them are in areas so cold that no water remains liquid.

In 2018, scientists worked on data from the Mars Express orbiter of who – which Announced a surprising discovery: it appears that the signals from the radar device reflected from the south pole of the red planet reveal a subterranean lake liquid. Since then, several reversals of this kind have been announced.

In a new article published in magazine Geophysical Research Letters, two scientists from the Jet Propulsion Laboratory (JPL) in NASA Describe finding dozens of similar radar reflections around the South Pole after analyzing a larger set of Mars Express data, but many of them in areas that must be too cold for water to remain liquid.

“We’re not sure if these signals are liquid water or not, but they appear to be more diffuse than the original paper found,” says Jeffrey Plott of JPL, co-principal investigator at MARSIS (Mars Advanced Subsurface Radar and Ionosphere Sounding ), which was jointly built by the Italian Space Agency and the Jet Propulsion Laboratory. Or liquid water is common under Antarctica to Mars Or are these signs indicative of something else?

frozen time capsule

Radar signals that were originally interpreted as liquid water were found in the area of Mars They are known as layered Antarctic deposits, which are named for the alternating layers of water ice, dry ice (frozen carbon dioxide) and dust that have settled there for millions of years.

These layers are thought to provide a record of how an axis is tilted Mars It has changed over time, just as changes in the Earth’s tilt have led to ice ages and warmer periods throughout our planet’s history. when Mars It had a low axial tilt, snowfall, and layers of dust accumulated in the area and eventually formed the thick layer of ice that is there today.

By broadcasting radio waves at the surface, scientists can look under these ice layers, and map them in detail. Radio waves lose their energy when they pass through material underground; Because it reflects off the spacecraft, it generally has a weaker signal. But in some cases, the signals returning from the interior of this region were even brighter than those coming from the surface. Some scientists interpreted these signals as indicating the presence of liquid water that strongly reflects radio waves.

Plaut and Aditya Kholer, the Arizona State University doctoral student who worked on the article while intern at the Jet Propulsion Laboratory, aren’t sure what the signs indicate. The areas presumed to contain liquid water extend 6 to 12 miles (10 to 20 kilometers) in a relatively small region from the south pole of Mars. Keller and Plot have extended the search for similarly strong radio signals to 44,000 measurements spread over 15 years of MARSIS data across the entire south pole region of Mars.

Unexpected “lakes”

The analysis revealed dozens of additional bright radar reflections in an area and depth range much greater than ever before. In some places, it was less than a mile from the surface, with temperatures estimated at minus 63 degrees Celsius, so cold that water would freeze, even if it contained salty minerals known as perchlorate, which can lower the water point. Freeze.

Kohler referred to a 2019 paper in which researchers calculated the heat required to melt subsurface ice in this region, and found that only recent volcanoes below the surface could explain the possible presence of liquid water below Antarctica.

“They found that it would take twice the estimated heat flux of geothermal Mars “To keep this water liquid,” Köhler said. One possible way to get this amount of heat is through volcanoes. However, we haven’t really seen any strong evidence of recent volcanic activity in Antarctica, so it seems unlikely that volcanic activity would allow liquid groundwater to exist throughout this region.”

What explains the bright reflections if it’s not liquid water? The authors cannot be certain. But his paper provides scientists with a detailed map of the region containing clues to its climatic history Mars, including the role of water in its various forms.

“Our maps bring us a few steps closer to understanding both the scope and cause of these baffling radar reflections,” Plott said. (Europa Press)

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