NASA finds Mars lake could have been teeming with life

NASA scientists have identified a site that could once have been home to alien life on Mars. Their robotic rover Curiosity examined the remains of an ancient freshwater lake and found evidence that it was a habitable environment.

A computer-generated image of Gale Crater from several images taken from orbiting probes. Credit: NASA/JPL

Curiosity, otherwise known as Mars Science Laboratory, has been trundling around Gale crater since it landed on the Red Planet on August 6 last year. The site was chosen after observations from orbiting space probes showed it was a promising area to investigate.

Curiosity’s advanced set of ten scientific instruments have carried out a vast range of tests on soil, rock and the thin atmosphere. It looked particularly at materials which seemed to show they had been affected by water.

This week, NASA experts have published five papers about the discoveries made during the first 100 martian days of its mission in the 154 km wide crater.

Evidence for the existence of a lake in the crater billions of years ago was confirmed from examination of mudstone in the crater’s Yellowknife Bay area. Curiosity’s on-the-spot research allowed the scientists to map the size and extent of the lake.

The possible extent of the habitable lake between the rim of Gale crater and Mount Sharp at its centre. The arrows indicate how water flowed into it. Credit: NASA/JPL-Caltech/MSSS

The team’s analysis showed that the lake was calm and likely had fresh water, containing key biological elements such as 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.

One of the mission scientists is Professor Sanjeev Gupta, from the Department of Earth Science and Engineering at Imperial College London. He said: “It is important to note that we have not found signs of ancient life on Mars. What we have found is that Gale Crater was able to sustain a lake on its surface at least once in its ancient past that may have been favourable for microbial life, billions of years ago. This is a huge positive step for the exploration of Mars.

“It is exciting to think that billions of years ago, ancient microbial life may have existed in the lake’s calm waters, converting a rich array of elements into energy. The next phase of the mission, where we will be exploring more rocky outcrops on the crater’s surface, could hold the key whether life did exist on the red planet.”

Curiosity mapped the ancient lake by studying stream deposits and recognising that water flowed from the rim of the crater into the basin. The mission team believe the area’s history probably included several lakes of different sizes forming and then being lost as climate conditions evolved.

Professor John Grotzinger, of California Institute of Technology, who is project scientist for the Curiosity mission, introduces the new research papers in the journal Science. Grotzinger says on his own website: “A long-standing goal of Mars environmental studies has been to understand the role of water throughout its geologic history. The presence of water is a strong indicator of potential habitability as well as of formerly different climatic conditions.”

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