Ancient Martian lake provides habitable conditions for life to evolve, say Indian scientists

New Delhi: An ancient Martian lake – an arid and barren landscape currently - may have held water for about 13,000 years and provided habitable conditions for microbial life to evolve, Indian scientists have found.

Located in the southern hemisphere of Mars, the 150 sq km lake - as big as one-fifth of Bengaluru – contained salts and clay minerals that are conducive to sustain life, they reported, opening up a new window to explore the red planet in future.

“The ancient lake is a part of a large basin whose size may go beyond 300 sq km. We found signatures of water activity for nearly 13,000 years. Also the lake environment was favourable for life to sustain,” Deepali Singh, a scientist at Physical Research Laboratory, Ahmedabad and first author of the paper told DH.

Has life evolved on Mars - is one of the long-standing questions in science. While it is well accepted that water – a precondition for life - flowed on the planet billions of years ago, many questions on its nature, timeline and other conditions to habitability are open.

Since NASA’s Mariner missions in the 1960s and 1970s, several nations including India have sent uncrewed missions to the earth’s nearest planetary neighbour to know about possible existence of water and lives. But a lot still is unknown.

The PRL team looked at a geographical depression in an area known as Terra Sirenum, which is high in chloride salt content. The site also has other salts and minerals that are known to help water flow even in very low temperatures.

The ancient lake site is part of an even larger basin and the depression is distinct from numerous craters that exist on the Martian surface.

As they reconstructed the lake’s past using geological and chemical clues, the scientists realised that it underwent cycles of drying and wetting over thousands of years.

Also the presence of salts like sulphates and chlorides indicate habitable conditions because these molecules are known to trap moisture for a long time, allowing microbial life to persist even in low water conditions.

"The water activity modelling show that the geochemical composition of the basin was favourable to support the origin of life forms and sustain them,” the PRL team comprising Deepali, Rishitosh Sinha and Kinsuk Acharyya reported, suggesting that the basin could be a promising site for future landing missions.

The scientists said water was available in the lake between 3.7-3.4 billion years and later at least a part of the depression was covered by lava flows.

“We showed the importance of topographic depressions for water to pond as previous studies were on crater lakes. The study has potential to alter the Martian water budgeting history as it shows any depression can hold water,” Deepali said.

The team used data generated by instruments aboard the Mars Reconnaissance Orbiter, a spacecraft that was launched by the US National Aeronautics and Space Administration and has been orbiting Mars since March 2006.

They are continuing with their investigation to check if there are signatures of even older flows of water on the planet.

“The future missions to Mars should take water cycles into account before deciding on exploration sites,” said Acharyya, a senior PRL scientist and team leader.

The study has appeared in a recent issue of Journal of Geophysical Research: Planets.