Scientists reexamining a mysterious signal from Mars’ south pole have offered a new potential explanation, and it doesn’t bode well for hopes of finding liquid water on the Red Planet.
In 2018, scientists use data from the European Space Agency Mars Express The orbiter’s Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument said they observed a radar signal that could be interpreted as evidence of liquid water. This strangely bright reflected signal came from a region known as the Ultima Scopuli at the south pole of Mars. Researchers studying the reflection now suggest that the signal comes not from the ice itself or even liquid water, but from underlying geological layers of minerals and frozen carbon dioxide. In particular, it became clear that the thickness of these layers creates an otherworldly reflection rather than what they consist of.
about soil, dazzling reflections like these often come from liquid water. For example, subglacial lakes that have been under more than 2 miles (3 kilometers) of ice for millions of years, such as Antarctica’s Lake Vostok, cause a bright radar signal like the one found in Antarctica. mars. However, the fact that such an event is possible on Mars does not guarantee the existence of liquid water.
Related: These dry ice glaciers on Mars move at its south pole
The research team used MARSIS radar data and computer simulations to investigate this mystery. To see how these materials would react to incoming light, the scientists simulated layers of ice and other materials, such as basalt rock, formed after ancient volcanic eruptions on Mars.
Because a lot of carbon dioxide is frozen at the south pole of Mars, Dan Lalich, a planetary scientist at Cornell University and lead author of the study, was sure to include these layers of ice in the simulations. One simulation in particular revealed that beneath a layer of carbon dioxide ice and water ice, the separation and thickness of the layers determined the reflectivity.
Previous studies conducted by Lalich found that certain minerals can also be reflected in this way. He believes that even the dust-covered ice sheets of the Red Planet are capable of this. In both cases, liquid water is not needed to create the reflection.
“I could use rock layers or particularly dusty water ice and get similar results,” he said. statement. “The point of this paper is really that the composition of the basal layers is less important than the thickness and separation of the layer.”
However, the new research does not mean that there is no possibility of liquid water on Mars.
“None of the work we’ve done refutes the possible presence of liquid water there,” Lalich said. “We just think the intervention hypothesis is more consistent with other observations. I’m not sure anything other than an exercise can prove either side of this argument definitively right or wrong.”
Whether beneath a glacier or deep within the planet’s scorched reddish surface, water—and perhaps traces of life—could still be lurking somewhere.
The research is described in a paper published in September. 28 inches Natural Astronomy (opens in new tab).
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