Shimmering ‘lakes’ under Mars’ south pole could be something else entirely

(ORDO NEWS) — What scientists thought were lakes of liquid water hidden under the south polar ice cap of Mars could be… ordinary old rock.

A new analysis has shown that the brightly shining radar signal is being interpreted as groundwater on the red planet could also have formed as a result of geological stratification.

This is not a foregone conclusion, but it does suggest that more solid evidence is needed before we can determine with certainty what is lurking there.

“Here we demonstrate that such reflections can occur as a natural result of subtle layer interference, without the use of any liquid water or other rare materials,” writes a team of researchers led by astronomer Dan Lalich of Cornell University in a new paper.

“This result, combined with other recent work, calls into question the likelihood of detecting liquid water beneath the South Polar Layered Deposits (SPLD).”

The mysterious signal was first spotted several years ago in radar data collected by the European Space Agency’s Mars Express satellite probe.

There, buried under the Martian south polar ice cap, scientists discovered a patch of unusually reflective material.

Subsequent searches have revealed more brilliantly shining underground areas, suggesting that whatever the first site was, it was definitely not unique. .

More interestingly, similar glowing spots have been found right here on Earth, also buried under the ice of the South Pole.

These are subglacial lakes, such as Lake Vostok, which form a network of liquid reservoirs under the Antarctic ice.

This led scientists to conclude that similar liquid reservoirs could be on Mars. There’s just one catch: Mars is thought to be too cold for liquid water, even under pressure under layers of ice, and with a freezing point lowered by the presence of salts.

So what are those shiny spots? For the study, Lalich and his colleagues ran simulations using layers of four materials known to be found on Mars.

Ground penetrating radar works by reflecting radio waves off an object or surface. How long it takes for these radio waves to bounce back, and how much, reveals the properties of materials below the planet’s surface, but not necessarily what those materials are.

The researchers created simulated layers. water ice, carbon dioxide ice, basalt, and atmosphere in various configurations and thicknesses, each with properties that reflect radar pulses in a particular way.

They then figured out what signals would be produced by these configurations. And they got something as bright as the Mars Express observations: a layer of water ice, dusty, sandwiched between two layers of carbon dioxide ice.

“I used layers of CO 2 embedded in water ice because we know it already exists in large quantities near the surface of the ice cap,” Lalić explains.

“In principle, however, I could use rock layers or even particularly dusty water ice and I would get the same results.

The point of this article is that the composition of the basal layers is less important than the thickness of the layers and the distance between them.”

This is not the only recent suggestion that the shimmer signal could have been created by something other than liquid water.

Last year, a team of scientists found that frozen clay emits the same level of radar radiation, and earlier this year another team suggested volcanic rock (of which Mars is plentiful) as the source.

With the addition of layers of rock and/or ice that are more consistent with what we know about Mars, the water explanation seems to be getting further and further away from plausibility.

Which would be a shame, because liquid water on Mars could have implications for its past and perhaps even present possibilities for life, as well as future manned missions to the red planet.

But it’s also possible that we’ll never know for sure.

“None of the work we’ve done disproves the possible existence of liquid water down there,” Lalić says. “We just think the interference hypothesis is more consistent with other observations.

I am not sure that anything other than the teachings can prove that either side in this dispute is definitely right or wrong.”

Which, given the depth of the site, the distance to Mars, and the difficulty of transporting things there (especially heavy drilling equipment) is unlikely to happen anytime soon.

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