According to the researchers, including those from Texas A&M University in the US, liquid water on Mars may have become unsustainable and evaporated as the planet’s atmosphere became thinner, and the pressure at the surface became lesser.
The study, published in the journal Nature Geoscience, noted that over 3 billion years ago the lake that was present in Gale Crater — an immense 95-mile-wide rocky basin that is being explored with the NASA Curiosity rover since 2012 — underwent a drying episode possibly linked to the global drying of Mars.
The Gale Crater formed about 3.6 billion years ago when a meteor hit Mars, the study noted.
“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,” said co-author of the study Marion Nachon from Texas A&M University.
According to Nachon, the salt ponds eventually formed during these drying periods. “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.
The researchers said that the salt ponds on Mars are similar to some found on the Earth such as those in a region called Altiplano near the Bolivia-Peru border.
Nachon added that 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.”
“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,” she said.
According to the researchers, the climate on Mars may have similarly fluctuated between wetter and drier periods.
The study also noted the types of chemical elements present in the liquid water that was present at the red planet’s surface at the time, and the type of environmental changes any potential life forms on Mars may have had to cope with, had they existed.