LONDON-An ancient fresh water lake on Mars could have sustained life on the red planet billions of years ago. Mudstones from Gale Crater, the landing site of the Curiosity rover, were formed in a lake that may have existed on the planet for hundreds of thousands of years, say scientists. The 150 kilometre-wide (93-mile) impact basin, with a mountain at its centre, is believed to have supported the lake - and possibly more than one - around 3.6 billion years ago. The analysis showed that the lake was calm and likely had fresh water, containing key biological elements including carbon, hydrogen, oxygen, nitrogen and sulphur.

Such a lake would provide perfect conditions for simple microbial life such as chemolithoautotrophs to thrive in. On Earth, chemolithoautotrophs are commonly found in caves and around hydrothermal vents.

The microbes break down rocks and minerals for energy. Mudstones generally form in calm conditions. They are created by very fine sediment grains settling layer-by-layer on each other in still water. The finding was made by a team of researchers from Nasa’s Mars Science Laboratory (MSL) Curiosity Rover mission, which includes a member from Imperial College London.