10 December 2013

Strong Evidence of Life in Ancient Lake at Mars Gale Crater

Scientists at NASA's Mars Science Laboratory have discovered evidence of an ancient lake on Mars that they believe may have supported life billions of years ago.

Using the Mars rover Curiosity, they analysed sedimentary rocks at Yellowknife Bay in the Gale Crater. Evidence from the analysis suggest that the site had at least one lake around 3.6 billion years ago. The analysis showed that the lake likely had fresh water and elements such as carbon, hydrogen, oxygen, nitrogen and sulphur which are suitable in sustaining life.

Compared to other previous Mars rovers, Curiosity is two times longer and five times heavier than the others. It carried equipment to gather samples of rocks and soil, process them and distribute them to onboard test chambers inside analytical instruments.

The Gale Crater, a depression made by an asteroid or comet billions of years ago, was the main target of Curiosity as it is believed to be made up of ancient sediment deposited when Mars still had abundant water at its surface.

Ancient Lake in Mars Crater

Scientists have found evidence that there was once an ancient lake on Mars that may have been able to support life, in research published today in the journal Science.

A team of researchers from NASA's Mars Science Laboratory (MSL) Curiosity rover mission, which includes a researcher from Imperial College London, have analysed a set of sedimentary rock outcrops at a site named Yellowknife Bay in Gale Crater, near the Martian equator. These mudstones have revealed that Gale Crater, a 150 km wide impact basin with a mountain at its centre, sustained at least one lake around 3.6 billion years ago.

The scientists believe that the lake may have lasted for tens if not hundreds of thousands of years.

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.

Video: Mars Science Laboratory Landing Site: Gale crater

Mudstones generally form in calm conditions. They are created by very fine sediment grains settling layer-by-layer on each other, in still water.

Professor Sanjeev Gupta, a member of the MSL mission from the Department of Earth Science and Engineering at Imperial College London and a co-author on the papers, says: "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."

In previous studies, Professor Gupta and the MSL team have found evidence of water on Mars' surface in other rocks such as conglomerates. However, the new research provides the strongest evidence yet that Mars could have been habitable enough for life to take hold.

The team analysed the geology and chemistry of the mudstones by drilling into the rock using the MSL six-wheeled science laboratory, which is remotely operated by the MSL team from the Jet Propulsion Laboratory in Pasadena in the USA.

The next step will see the team using the rover to explore Gale Crater for further evidence of ancient lakes or other habitable environments in the thick pile of sedimentary rocks scattered across the crater's surface.


Imperial College London
Mars Science Laboratory (MSL)
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