Curiosity ups the ante in extraterrestrial life debate

Rover reveals strongest evidence yet that Mars was capable of supporting living organisms.


WEBWIRE – Thursday, December 12, 2013

NASA’s Curiosity rover has found evidence of an ancient lake on Mars that has all the necessary ingredients to support microbial life, according to a paper published this week in the journal Science.

Curiosity made the discovery while analysing rocks near its landing site at Gale Crater, a spot NASA scientists chose because they thought that the crater floor might have once been a vast, ancient lake.

The new evidence verifies that a lake did in fact exist and reveals just how hospitable it may have been.

The lake existed around 3.6 billion years ago, around the same time microbial life was getting started on Earth, and may have persisted for tens of thousands of years.
Conditions for life

The lake bed was made up of clays, very fine sediments that need calm conditions to form. Previous evidence for flowing water on Mars includes stream channels and rounded pebbles in ancient stream beds, but this is the first evidence of calm freshwater.

Museum mineralogist and Martian clay researcher Dr Joe Michalski said the composition of the clays is particularly interesting, indicating the lake had low salinity and low acidity and was rich in chemical elements necessary for life. ‘These conditions are good for life as we know it,’ he said.

Microbial life on Earth often uses sunlight to produce energy through photosynthesis, but if life existed in the Martian lake, that would likely not have been the case. Instead, microbes would have processed chemicals in the rocks to get energy. These types of microbes also exist on Earth today in specialised environments, such as around hydrothermal vents.
Continuing the search

No environment on Earth today is exactly like the Martian lake, and the current evidence cannot say whether life actually did exist there. ‘What we can say is that the environment captured in this geological setting is one that would have been suitable for life to exist and possibly flourish if there was such a thing on Mars at that time,’ said Dr Michalski.

Curiosity’s next destination is more sedimentary rocks on the crater floor, which it will visit in the coming months, en route to Mount Sharp. As it climbs the slopes, it will analyse more rocks to build up a picture of Mars’ geological past, potentially spotting more signs of a planet once hospitable to life.



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