Remnants of a mineral found in Mars have led scientists to posit that the red planet may have been habitable for millions of years in the past.
Published in Nature Astronomy, the study is based on an analysis of clay samples collected from the Gale Crater on Mars by NASA’s Curiosity rover in 2016. The researchers note this clay can only form in life-supporting environments akin to that on Earth.
Drilling into the crater, Curiosity found the presence of a particular clay mineral called glauconitic clay, an iron potassium phyllosilicate mineral also found here on the Earth. Its formation requires stable geological conditions over a long period — conditions that would also have made the planet suitable for life.
“Glauconitic clays can be used as ‘a proxy’ for stable conditions,” Elisabeth Losa-Adams at the University of Vigo, Spain, the study’s lead author, said in a statement. “The conditions under which these minerals form are friendly for the presence of life.”
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This discovery has led researchers to conclude that Mars was probably habitable for over a million years — even if just in parts. The stable, habitable conditions scientists are referring to denote temperatures around –3 to 15°C, and the existence of water with a neutral pH — that is neither acidic, not basic.
“[T]he geochemical parameters required for their formation would have also created supportive habitable conditions for potential organisms,” Losa-Adams, whose research areas are mineralogy, geochemistry, and paleo-climate, told DailyMail.
The site in question was already believed to have housed an ancient lake for up to 10 million years — around 3.5 billion years ago. This was when the planet’s thicker atmosphere may have been able to support liquid water on its surface. But until now, it was unclear whether the lake indeed had conditions suitable for life — a question that the present research had led scientists to lean positively towards.
“The existence of glauconitic clays indicates the presence of liquid water remaining long-term under steady-state conditions… The conditions under which these minerals form are friendly for the presence of life,” explained Losa-Adams.
However, while the discovery indicates habitability, it doesn’t provide evidence of life itself.
