Saturn's moon Titan has a very salty ocean   
       
   July 2, 2014:  Scientists analyzing data from NASA's Cassini mission have firm   
   evidence of an ocean inside Saturn's largest moon, Titan, which might be as   
   salty as the Earth's Dead Sea. The findings are published in this week's   
   edition of the journal Icarus.   
       
   "This is an extremely salty ocean by Earth standards," said the paper's lead   
   author, Giuseppe Mitri of the University of Nantes in France. "Knowing this   
   may change the way we view this ocean as a possible abode for present-day   
   life, but conditions might have been very different there in the past."   
       
   http://www.jpl.nasa.gov/news/news.php?release=2014-217   
       
   Researchers found that Titan's ice shell, which overlies a very salty ocean,   
   varies in thickness around the moon, suggesting the crust is in the process of   
   becoming rigid. Image Credit: NASA/JPL/SSI/Univ. of Arizona/G. M   
   tri/University of Nantes   
       
   The new results come from a study of gravity and topography data collected   
   during Cassini's repeated flybys of Titan during the past 10 years.   
   Researchers found that a relatively high density was required for Titan's   
   subsurface ocean in order to explain the gravity data. This indicates the   
   ocean is probably an extremely salty brine of water mixed with dissolved salts   
   likely composed of sulfur, sodium and potassium. The density indicated for   
   this brine would give the ocean a salt content roughly equal to the saltiest   
   bodies of water on Earth.   
       
   Their findings also support the idea that the moon's icy shell is rigid and in   
   the process of freezing solid.   
       
   The thickness of Titan's ice crust appears to vary slightly from place to   
   place. The researchers said this can best be explained if the moon's outer   
   shell is stiff, as would be the case if the ocean were slowly crystalizing,   
   and turning to ice. Otherwise, the moon's shape would tend to even itself out   
   over time, like warm candle wax. This freezing process would have important   
   implications for the habitability of Titan's ocean, as it would limit the   
   ability of materials to exchange between the surface and the ocean.   
       
   The data also touch on a major mystery: The presence of methane in Titan's   
   atmosphere. Scientists have long known that Titan's atmosphere contains   
   methane, ethane, acetylene and many other hydrocarbon compounds. But sunlight   
   irreversibly destroys methane after tens of millions of years, so something   
   has replenished methane in Titan's thick air during the moon's 4.5   
   billion-year history.   
       
   The rigid ice shell model published in Icarus suggests that any outgassing of   
   methane into Titan's atmosphere must happen at scattered "hot spots" (like the   
   hot spot on Earth that gave rise to the Hawaiian Island chain), not from a   
   broader process such as convection or plate tectonics.   
       
   "Titan continues to prove itself as an endlessly fascinating world," said   
   Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory   
   (JPL) in Pasadena, California, who was not involved in the study.  "With our   
   long-lived Cassini spacecraft, we're unlocking new mysteries as fast as we   
   solve old ones."   
       
   The Cassini-Huygens mission is a cooperative project of NASA, the European   
   Space Agency and the Italian Space Agency. JPL manages the mission for NASA's   
   Science Mission Directorate in Washington.   
       
   For more information about Cassini, visit http://www.nasa.gov/cassini   
       
   Credits:  Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.99   
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