The “lakes” buried on Mars may just be frozen clay

Bright reflections detected by radar below the South Pole Mars A new study found that it may not be an underground lake as previously thought, but a clay deposit.

For decades, scientists have suspected that water lurks under the polar ice caps of Mars, just like on Earth. In 2018, researchers used the MARSIS radar detector on the European Space Agency’s Mars Express spacecraft to detect Evidence of the lake Hidden under the ice cap of this red planet Antarctica, by 2020, they have discovered There are many super salty lakesScientists point out that if these lakes are remnants of water that once existed on the surface, then these reservoirs may have lived and may still exist.

However, according to Isaac Smith, the lead author of the new study, given the current understanding of the red planet, in order to form and maintain liquid water in this place on Mars, incredible heat and salt may be required. Planetary scientist and his colleagues at York University in Toronto.

York and his team say that clay minerals known to exist in the Antarctic region of Mars can explain these radar reflections without having to call water lakes.

“In the Martian community, people are skeptical of the lake’s interpretation, but no one offers a truly viable alternative,” Smith told Space.com. “Therefore, it is exciting to be able to prove that other things can explain the results of radar observations and prove that the material exists where it is needed. I like to solve puzzles, and Mars has countless puzzles.”

Scientists focused on the mineral called montmorillonite, a type of clay whose chemical composition is closer to volcanic rock than other types of clay. Montmorillonite is formed when the eroded volcanic rock interacts with water and undergoes a slight chemical change. They pointed out that these clays can hold a lot of water.

Montmorillonite on Mars is extremely rich, mainly concentrated in the southern highlands. “On Earth, they usually appear near volcanoes in Alaska or Central America, but they can be found on all continents,” Smith said.

In the laboratory, researchers cool the smectite to minus 45 degrees Fahrenheit (minus 43 degrees Celsius), a temperature that may be found on Mars. They found that even when mixed with other materials, water-containing montmorillonite can produce the kind of bright radar reflections detected by MARSIS (short for “Mars Advanced Radar for Underground and Ionospheric Detection”).

When Smith and his colleagues analyzed the visible and near-infrared data previously collected from the South Pole of Mars, they also found evidence of montmorillonite there.They believe that the south pole of Mars formed montmorillonite during the warm period, when the area was Covered by waterThese water-bearing clays were later buried under water ice.

“Looking back, when will Mars is more humidThis supports the evidence that liquid water exists in a larger area than we expected,” Smith said. “Because these clays are located in and below the Antarctic canopy, it must have been warm enough to support the liquid long ago. “

All in all, the researchers believe that green earth is a more feasible explanation for the bright radar reflections seen there rather than the super salty lake.

“Science is a process, and scientists are always trying to find the truth,” Smith said. “To show that another material other than liquid water can be used for radar observations does not mean that the release of the first batch of results in 2018 is wrong. This provides a lot of people with ideas for new experiments, modeling, and observations. These ideas It will be transformed into other investigations on Mars, and it has been applied to my team.”

In the future, “I want to repeat the measurement in colder temperatures and more diverse clays,” Smith said. “I suspect that other types of clay found on Mars can also produce these reflections, and it’s best to follow them up.”

Scientist details Their findings Today (July 29) in the magazine Geophysical Review Letters.