Earth & Climate

Mars once had salt lakes like those on Earth

Mars once had salt lakes that are like those on Earth and has experienced wet and dry periods, as indicated by an international group of researchers that incorporates a Texas A&M University College of Geosciences analyst.

Marion Nachon, a postdoctoral research partner in the Department of Geology and Geophysics at Texas A&M, and colleagues have had their work published in the current issue of Nature Geoscience.

The group inspected Mars’ geographical terrains from Gale Crater, an immense 95-mile-wide rocky basin that is being investigated with the NASA Curiosity rover since 2012 as a feature of the MSL (Mars Science Laboratory) mission.

The outcomes show that the lake that was available in Gale Crater more than 3 billion years back experienced a drying episode, possibly connected to the global drying of Mars.

Gale Crater formed about 3.6 billion years back when a meteor hit Mars and made its huge effect crater.

“Since then, its geological terrains have recorded the history of Mars, and studies have shown Gale Crater reveals signs that liquid water was present over its history, which is a key ingredient of microbial life as we know it,” Nachon said. “During these drying periods, salt ponds eventually formed. It is difficult to say exactly how large these ponds were, but the lake in Gale Crater was present for long periods of time — from at least hundreds of years to perhaps tens of thousands of years,” Nachon said.

So what befell these salt lakes?

Nachon said that Mars likely became dryer after some time, and the planet lost its planetary magnetic field, which left the atmosphere presented to be stripped by solar wind and radiation more than a huge number of years.

“With an atmosphere becoming thinner, the pressure at the surface became lesser, and the conditions for liquid water to be stable at the surface were not fulfilled anymore,” Nachon said. “So liquid water became unsustainable and evaporated.”

The salt lakes on Mars are believed to be like some found on Earth, particularly those in a region called Altiplano, which is close to the Bolivia-Peru border.

Nachon said the Altiplano is an arid, high-altitude plateau where rivers and streams from mountain ranges “do not flow to the sea but lead to closed basins, similar to what used to happen at Gale Crater on Mars,” she said. “This hydrology creates lakes with water levels heavily influenced by climate. During the arid periods, Altiplano lakes become shallow due to evaporation, and some even dry up entirely. The fact that the Altiplano is mostly vegetation-free makes the region look even more like Mars,” she said.”

Nachon included that the investigation shows that the old lake in Gale Crater experienced at least one episode of drying before “recovering.” It’s likewise conceivable that the lake was segmented into isolated lakes, where a portion of the lakes could have experienced more vanishing.

Since up to now just only one location along the rover’s way shows such a drying history, Nachon said it may give clues about what number of drying episodes the lake experienced before Mars’ climate became as dry as it is as of now.

“It could indicate that Mars’s climate ‘dried out’ over the long term, in a way that still allowed for the cyclical presence of a lake,” Nachon said. “These results indicate a past Mars climate that fluctuated between wetter and drier periods. They also tell us about the types of chemical elements (in this case sulfur, a key ingredient for life) that were available in the liquid water present at the surface at the time, and about the type of environmental fluctuations Mars life would have had to cope with if it ever existed.”

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