the secret was an invisible ice “blanket”

For decades, planetary geologists have faced a paradox that didn’t quite add up. On the one hand, the missions like Curiosity in Gale Crater show irrefutable evidence that there were lakes of liquid water for thousands or millions of years. On the other hand, climate models insist that ancient Mars It was a cold place.with temperatures well below freezing point.

A new paradigm. The question in this case is quite clear: how can there be stable liquid water on a planet where the thermometer barely rises above zero degrees? A new study led by Rice University and published in AGU Advances seems to have found the missing piece in the puzzle: seasonal ice shields.

The LakeM2ARS model. To solve the mystery, the team of researchers developed a specific model called LakeM2ARS. This model included everything we know about terrestrials, but adapted to the extreme conditions that existed on Mars 3.6 billion years ago. That is, a climate with less sunlight due to a younger Sun, an atmosphere with much more carbon dioxide and much more aggressive freezing and thawing cycles than those on Earth.

Using these models, the researchers began to apply different climatic situations, covering a period of 30 Martian years, which is equivalent to 56 Earth years. The results in this case pointed to something quite fascinating: the water in the lakes only froze on their surface, creating a shield of ice.

A natural “blanket”. The research introduces the concept of “ice shield” or “natural blanket.” Instead of being a solid block of ice, the Gale Crater lakes they would have been protected by a seasonal ice sheet thin enough to allow dynamic processes beneath it.

In this way, this “blanket” acted as a thermal insulator, since ice has a low thermal conductivity. The good thing about this is that once a layer forms on the surface, the liquid water underneath is “trapped” and protected from the frigid air, maintaining a stable temperature even if the thermometer plummets outside.

Another advantage. Beyond this we can see that the low Martian pressure causes liquid water to tend to sublimate quickly. The ice thus acted as a physical plug, conserving the water inventory for decades or even centuries.

But it is not that the water underneath was completely cold, but rather that since it was a thin layer, sunlight could pass through it (similar to what happens in the lakes of the Dry Valleys of Antarctica), generating a slight internal heating.

The missing piece. One of the biggest criticisms of the cold Mars hypothesis was the absence of geomorphological traces. The big question we can undoubtedly ask ourselves is that if Mars was a freezer, where are the large moraine deposits and the scars left by the glaciers as they advance?

The Rice University study gives an elegant answer: the ice was too thin. Since they were not massive glaciers, but rather thin and seasonal layers, they did not have the weight or dynamics necessary to erode the terrain drastically. This fits perfectly with Curiosity’s observations, which show fine-grained lake sediments, typical of calm waters, and not the chaos of rocks that a glacier would leave behind.

Microscopic life. This discovery changes the rules of the game for astrobiology, which wants above all to search for evidence of life on the red planet. In this case, the theory is put forward that if Martian lakes were sealed by ice, they became extremely stable environments. Under the ice, life would have been protected from harmful UV radiation and extreme temperature fluctuations.

This is why Mars did not need to be a tropical paradise to be habitable; It was enough for him to have a good “armor” of ice that would keep his liquid oases safe from the icy vacuum of space.

Images | BoliviaIntelligent

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