Friday, August 26, 2016

TITAN: Could there be Life in Titan's Methane Sea?

   If life can exist in the oily seas of Saturn's largest moon, then perhaps we will find it all over the Universe.
   Katia Moskvitch explores the possibilities of life on another planet.

Welcome to Titan, the largest of Saturn’s many moons. This weird world, about the size of Mercury, is utterly alien and yet strangely Earth-like.
   Like Earth, Titan’s atmosphere is mostly nitrogen, but mixed with methane. It has mountains, valleys, dunes – and rivers and lakes too, but filled with an oily hydrocarbon cocktail of ethane and methane. Titan is the only other place in our neighborhood with large bodies of liquid on its surface. 
   And for some scientists that means the potential for life.

  “We think that life requires liquid,” says NASA Ames Research Centre planetary scientist Chris McKay. Life needs a medium that brings chemicals close enough together to interact but not so close that they can’t move. Gases are too diffuse and solids too cramped to allow life as we know it to evolve. However, “there’s a bias that the liquid has to be water,” adds McKay. For good reasons. Water is an excellent solvent for the chemistry of life. It remains liquid across a wide temperature range and its polar nature helps complex molecules such as DNA and proteins to form their structure.

   Most of our space exploration has revolved around the search for water – from NASA robots crawling the dusty Martian landscape to telescopes looking for distant planets that orbit their stars in the “Goldilocks zone” – not too hot and not too cold for liquid water. 
   Water-based life is something we know how to look for. Our telescopes probe the atmospheres of planets for its key signatures – oxygen and methane.


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