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   Titan's Underground Ocean    
      
   June 28, 2012: Data from NASA's Cassini spacecraft have revealed Saturn's moon   
   Titan likely harbors a layer of liquid water under its ice shell. The finding   
   appears in today's edition of the journal Science.    
      
   "Cassini's detection of large tides on Titan leads to the almost inescapable   
   conclusion that there is a hidden ocean at depth," said Luciano Iess, the   
   paper's lead author and a Cassini team member at the Sapienza University of   
   Rome, Italy. "The search for water is an important goal in solar system   
   exploration, and now we've spotted another place where it is abundant."    
      
   http://science.nasa.gov/media/medialibrary/2012/06/28/splash_.jpg   
      
   This artist's concept shows a possible scenario for the internal structure of   
   Titan, as suggested by data from NASA's Cassini spacecraft. Image credit: A.   
   Tavani   
      
   The evidence is tidal.  Saturn's powerful gravity stretches and deforms Titan   
   as the moon moves around the gas giant planet. If Titan were composed entirely   
   of stiff rock, the gravitational attraction of Saturn should cause bulges, or   
   solid "tides," on the moon only 3 feet (1 meter) in height. Instead, the data   
   show Saturn creates solid tides approximately 30 feet (10 meters) in height.   
   This suggests Titan is not made entirely of solid rocky material.    
      
   At first, scientists were not sure Cassini would be able to detect the bulges   
   caused by Saturn's pull on Titan. Cassini succeeded, however, by measuring   
   Titan's gravitational field during six close flybys from Feb. 27, 2006, to   
   Feb. 18, 2011. These gravity measurements, collected with the aid of NASA's   
   Deep Space Network (DSN), revealed the size of Titan's tides.    
      
   "We were making ultrasensitive measurements, and thankfully Cassini and the   
   DSN were able to maintain a very stable link," said Sami Asmar, a Cassini team   
   member at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The tides on   
   Titan pulled up by Saturn aren't huge compared to the pull the biggest planet,   
   Jupiter, exerts on some of its moons. But, short of being able to drill on   
   Titan's surface, the gravity measurements provide the best data we have of   
   Titan's internal structure."    
      
   http://www.nasa.gov/multimedia/videogallery/index.html?media_id=147413591   
      
   A movie shows "tides" on Titan raised by Saturn's gravity (exaggerated for   
   clarity). Play itAn ocean layer does not have to be huge or deep to create the   
   observed tides. A liquid layer between the external, deformable shell and a   
   solid mantle would enable Titan to bulge and compress as it orbits Saturn.   
   Because Titan's surface is mostly made of water ice, which is abundant in   
   moons of the outer solar system, scientists believe Titan's ocean is likely   
   mostly liquid water.    
      
   On Earth, tides result from the gravitational attraction of the moon and sun   
   pulling on our surface oceans. In the open oceans, those can be as high as two   
   feet (60 centimeters). The gravitational pulling by the sun and moon also   
   causes Earth's crust to bulge in solid tides of about 20 inches (50   
   centimeters).    
      
   The presence of a subsurface layer of liquid water at Titan is not by itself   
   an indicator for life. Scientists think life is more likely to arise when   
   liquid water is in contact with rock, and these measurements cannot tell   
   whether the ocean bottom is made up of rock or ice.    
      
   The results have a bigger implication for the mystery of methane replenishment   
   on Titan.  Methane is abundant in Titan's atmosphere, yet researchers believe   
   the methane is unstable, so there must be a supply to maintain its abundance.    
      
   "The presence of a liquid water layer in Titan is important because we want to   
   understand how methane is stored in Titan's interior and how it may outgas to   
   the surface," said Jonathan Lunine, a Cassini team member at Cornell   
   University, Ithaca, N.Y. "This is important because everything that is unique   
   about Titan derives from the presence of abundant methane, yet the methane in   
   the atmosphere should be destroyed on geologically short timescales."    
      
   A liquid water ocean, "salted" with ammonia, could produce buoyant   
   ammonia-water liquids that bubble up through the crust and liberate methane   
   from the ice. Such an ocean could serve also as a deep reservoir for storing   
   methane.    
      
   For more information about Cassini's mission to Saturn, visit: h   
   tp://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .    
      
      
   Production editor: Dr. Tony Phillips | Credit: Science@NASA   
      
   More Information    
   The Cassini-Huygens mission is a cooperative project of NASA, the European   
   Space Agency and the Italian Space Agency. The mission is managed by JPL for   
   NASA's Science Mission Directorate in Washington. DSN, also managed by JPL, is   
   an international network of antennas that supports interplanetary spacecraft   
   missions and radio and radar astronomy observations for the exploration of the   
   solar system and the universe. The network also supports selected   
   Earth-orbiting missions. Cassini's radio science team is based at Wellesley   
   College in Massachusetts. JPL is a division of the California Institute of   
   Technology in Pasadena.    
      
      
   Regards,   
      
   Roger    
   --- timEd/386 1.10.y2k+   
    * Origin: NCS BBS - Houma, LA - (1:3828/7)