As the Perseverance rover begins its journey to look for signs of ancient microbial life in the Jazero crater, a new study of soil samples from the Gale crater has strengthened the possibility that life once flourished on the now-barren Mars.
The Gale crater is home to Nasa’s Curiosity rover, which is about 3,700 kilometres away from Perseverance’s location.
Researchers studying the crater said investigations by the Mars Science Laboratory have confirmed the presence of an ancient lake that existed in the Gale crater for up to 10 million years, indicating that parts of Mars may once have been habitable for thousands of years.
The report, published in the journal Nature Astronomy, stated that the lake was filled with sediments that eventually converted to a compacted sandstone. Scientists believe that the lake existed about 3.5 billion years ago when the planet had a thicker atmosphere needed to support liquid on the surface. However, it is unclear if the lake had the accurate conditions to support life.
The study was conducted using X-Ray data from the Chemistry and Mineralogy instrument (CheMin) onboard the Curiosity rover. It characterised the degree of disorder of clay minerals in the Murray formation at Gale crater. The analysis showed the samples having structural and compositional similarities with clay found in liquid bodies for extended periods of time.
The samples, drilled by the Curiosity rover in 2016 from the crater, showed the presence of mineral remnants of glauconitic (iron potassium silicate), suggesting temperatures could have once been stable on the planet, ranging between -3 to 15 degrees Celcius. Glauconite formation takes place in low-sedimentation-rate and open-marine environments on Earth.
However, scientists maintained that while glauconitic clay was an indicator of habitability, it does not prove the existence of life. This is not the first such crucial discovery by the rover, which reached Mars in 2012.
Powered by a radioisotope, the rover had also found that that Mars might have organic salts on its surface. Analysing data from the rover, scientists concluded that iron, calcium, magnesium oxalates, and acetates, affected by radiation and oxidation might have decomposed into organic salts in Martian surface sediments. These salts could have been formed by geologic processes or were remnants of ancient microbial life.
While the Perseverance rover is looking for ancient microbial life on the surface, the European Space Agencys forthcoming ExoMars rover, which is equipped to drill down to two meters, will carry an instrument to analyse the chemistry of these deeper Martian layers to better its understanding of the subsurface.

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