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article imageLife on Mars could have existed in ancient fresh water lake

By Robert Myles     Dec 9, 2013 in Science
London - Scientists analysing data gathered by NASA’s Mars Science Laboratory (MSL) Curiosity rover mission have uncovered evidence pointing to an ancient lake that once existed on Mars that may have supported life.
Their research was published Monday in the journal Science.
The researchers analysed a set of sedimentary rocky outcrops surveyed by Curiosity rover at Yellowknife Bay in Gale Crater near the Martian equator. Curiosity rover started its exploration of Yellowknife Bay mid-December 2012. The Gale Crater area of Mars is a 150 kilometer (94 miles) wide impact basin with a mountain at its center.
The analysis of focused on a type of sedimentary rock known as mudstones. Mudstone, or mudrock, is a fine grained sedimentary rock which originally comprised clay or mud. Mudstones generally form in calm, still water conditions and are created by very fine sediment grains settling layer-by-layer on each other. Over time, the material has been compressed and hardened by geological forces to form rock.
These Martian mudstones revealed that Gale Crater was home to at least one lake around 3.6 billion years ago. According to the researchers, the lake may have been in existence for tens, if not hundreds, of thousands of years.
The geology and chemistry of the mudstones was analysed remotely after mudstone samples were drilled using the MSL six-wheeled science laboratory. This automated lab is operated by the MSL team from the Jet Propulsion Laboratory in Pasadena, California.
The scientists were particularly interested in the lake’s composition. Not only was it likely to have been relatively calm, as evidenced by the mudstone formation, but it probably contained fresh water. That, combined with biological elements like carbon, hydrogen, oxygen, nitrogen and sulphur, would have provided perfect conditions in which simple microbial life might thrive.
Drawing a parallel with life on Earth, the researchers compared the conditions in which chemolithoautotrophs are able to survive.
To describe chemolithoautotrophs as a biological curiosity understates just how weird a life-form they are. Unlike most life on Earth which depends, either directly or indirectly, on sunlight and photosynthesis to generate organic carbon and cellular energy, chemolithoautotrophic bacteria are microbes that break down rocks and minerals for energy. These microbes, usually found in caves and around hydrothermal vents, utilize chemicals (chemo) from the bedrock (litho) as the energy source to manufacture their own (auto) food (troph).
As touched upon by one of the researchers, the existence of chemolithoautotrophs in some of the harshest environments on Earth in no way guarantees that life has evolved elsewhere in the Universe. 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 research papers, 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.”
Professor Gupta continued, "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."
Previously, the same MSL team found evidence of water having existed in other Martian rocks. This latest research, however, provides the strongest evidence to date that in part of Gale Crater, Mars may at one time have provided a suitable environment for life to take hold.
The next stage of the mission will involve Curiosity rover make further sorties in Gale Crater, seeking out further evidence of ancient lakes or other habitable environments in the thick carpet of sedimentary rocks scattered across the crater's surface.
More about Mars rover curiosity, mars curiosity rover, nasa curiosity mars, Gale Crater, Yellowknife Bay
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