The search for life outside of Earth has become one of the greatest obsessions of astronomers, and Mars is considered the most privileged place for such discoveries. Life thrives in the presence of water, and recent research has attracted worldwide interest, showing the existence of underground lakes on the red planet.
Some scientists believe that the radar signals that indicate the presence of water deep in the surface of these lakes may come from clay rather than water. Three articles published last month revealed mysterious signs that refute the ocean hypothesis.
In 2018, a team led by Roberto Orosei of the Italian Institute of Astrophysics published evidence of the existence of an underground lake under the Martian south pole. The team checked the radar data on the European Space Agency (ESA) Mars Express Orbiter displays a bright signal below the polar cap. Scientists believe that these signals can be interpreted as liquid water.
The orbiter uses radar signals to penetrate rocks and ice, which change with the reflection of different materials. However, after testing in a cold laboratory, the researchers now assume that the signal does not come from water.
Researchers now say that many of these lakes may be too cold for the water to keep flowing. Aditya R. Huller and Jeffrey J. Plaut of NASA’s Jet Propulsion Laboratory (JPL) analyzed 44,000 radar echoes from the bottom of the lid during 15 years of observation and found many of these signals in areas close to the surface. Because it must be too cold to keep the water liquid.
Two independent teams analyzed the data to see if there were other things that could generate these signals. Although Carver Bierson of ASU completed theoretical research by proposing several materials (including clay) that may trigger signals, Isaac Smith of York University measured the properties of smectites and discovered a group of clays all over Mars.
The team then used the MRO to check for the presence of clay on Mars, which was equipped with a mineral mapping device called a compact reconnaissance imaging spectrometer. They discovered the smectites scattered on the ice sheet. The Jet Propulsion Laboratory said in a statement: “Smith’s team has shown that frozen smectite can cause reflections that do not require unusual amounts of salt or heat, and they exist in the South Pole of Mars.”