“Follow the water” scientists have long been searching for life outside Earth. After all, the only known cradle of life in the cosmos is the watery planet we call home. But now more evidence suggests that the potential for liquid water found on Mars may not be so isolated, researchers report on September 26. Nature Astronomy.
In 2018, scientists announced the discovery of a large subsurface lake near Mars’ south pole (SN: 7/25/18). They claim that – and the following observations suggest additional reservoirs of liquid water on the Red Planet (SN: 9/28/20) — fueled by the excitement of finally discovering an extraterrestrial world possibly conducive to life.
But the investigators then proposed that those findings should not be held to scrutiny. In 2021 one group suggested that fossilized clays and glacial till, rather than liquid water, were responsible for the strong signals that the researchers observed (SN: 7/16/21). A Mars-orbiting spacecraft will direct radiation at the Red Planet and measure the frequency and intensity of the reflected waves to determine what is being carried beneath the Martian surface.
Now another team has shown that ordinary layers of rock and ice can produce many of the same radar signals previously attributed to water. Planetary physicist Dan Lalich of Cornell University and colleagues calculated how flat layers of bedrock, water ice and carbon dioxide — all known to be abundant on Mars — reflect the radiation waves. “It was a pretty simple analysis,” says Lalich.
The researchers found that they thought they could reproduce some anomalous strong radar signals due to liquid water. Individual wear marks come from different layers of rock and ice added together when the layers are of a certain thickness, says Lalich. It produces a stronger signal that is collected by space instruments. But those tools can’t always tell the difference between a radio wave coming from a single layer and one that comes from multiple layers, he says. “Not as one thought to the law.”
These results do not recognize liquid water from Mars, Lalich and colleagues. “It just says it’s different,” he said.
The new discovery is a “probable session,” says Aditya Khuller, a planetary scientist at Arizona State University in Tempe, who was not involved in the research. But until scientists get a lot more data from the Red Planet, it will be difficult to know whether liquid water really exists on Mars, Khuller says. “It is important to be in this part of INTEGER.”
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