It can be argued that the researchers’ belief that there are lakes of liquid water hiding under the surface of Mars, may in fact be deposits of frozen mud.
A new analysis of radar data from 2018 from the MARSIS instrument on the European Space Agency’s Mars Express spacecraft supports the idea of liquid water on Mars, says research scientist at the Planetary Science Institute, Isaac Smith.
“To date, all previous research papers have only been able to suggest gaps in the lakes debate,” Smith said in a statement. “This is the first paper to show that another substance is the most likely cause of the observations.”
“Now, our paper presents the first plausible, and by far the most likely, alternative hypothesis to explain the MARSIS observations. Specifically, hard clays frozen to very cold temperatures can cause reversals.”
Given that it would take large amounts of heat and salt to maintain liquid water in Mars’ southern ice cap, Smith says it’s more plausible that minerals known as smectites, a type of igneous rock-like clay that is “extremely available” on Mars, are what. It prompted scientists initially to interpret the radar readings as liquid water.
The researchers cooled smectites in the lab to -45 degrees Fahrenheit. At this temperature, water-bound smectites can generate the bright radar reflections detected by MARSIS.
Smith explained that “smectites is a type of clay that is abundant on the surface of Mars, covering approximately 50% of the surface, and is particularly concentrated in the southern hemisphere.”
He continued: “Recent theoretical work suggested that clays could have bright reflections, but no one has frozen them to the temperatures we see on Mars – 40 to 50 degrees below freezing – and they have measured them, and they have not identified these minerals in the Antarctic.”
The average temperature on Mars is roughly -81 degrees Fahrenheit on average, according to NASA.
However, it can range from -220 degrees Fahrenheit in winter at the poles to a strong 70 degrees Fahrenheit at low latitudes in summer, according to the National Weather Service.
And in 2018, the Mars Advanced Radar for Subsurface and Ionosphere (MARSIS) detected regions of the radar evidence of a liquid lake beneath Mars’ south polar ice.
Two years later, researchers found several salt lakes in the area, each about six miles wide.
Smith is also convinced that lakes made of liquid water are “hard to support at this point”, but not everyone, including Jeffrey Plot of NASA at JPL, is convinced.
In a separate statement, Plott said: “In planetary science, we often get a little closer to the truth. The original paper did not prove that it was water, and these new papers do not prove that it was not. But we are trying to narrow the range of possibilities as much as possible in order to reach a consensus.” .
The new study was published in Geophysical Research Letters.
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