New Evidence for Liquid Water on Europa   
       
   Nov. 16, 2011:  In a potentially significant finding in the search for life   
   beyond Earth, scientists studying data from NASA's Galileo probe have   
   discovered what appears to be a body of liquid water the volume of the North   
   American Great Lakes locked inside the icy shell of Jupiter's moon Europa.   
       
   The water could represent a potential habitat for life, and many more such   
   lakes might exist throughout the shallow regions of Europa's shell, say   
   researchers writing in the journal Nature.   
       
   "The data opens up some compelling possibilities," said Mary Voytek, director   
   of NASA's Astrobiology Program at agency headquarters in Washington. "However,   
   scientists worldwide will want to take a close look at this analysis and   
   review the data before we can fully appreciate the implication of these   
   results."   
       
   http://www.utexas.edu/know/2011/11/16/europa_great_lake/   
       
   A new study of data from the Galileo probe suggest Grate-Lake-sized bodies of   
   water exist in the icy shell of Europa. Credit: Britney Schmidt/Dead Pixel   
   FX/Univ. of Texas at Austin [video] The Galileo spacecraft, launched by the   
   space shuttle Atlantis in 1989, provided scientists decades of data to analyze   
   before the probe plunged into Jupiter's atmosphere in 2003. One of the most   
   significant discoveries was the inference of a global salt water ocean below   
   the surface of Europa. This ocean is deep enough to cover the whole surface of   
   Europa and contains more liquid water than all of Earth's oceans combined.   
   However, being far from the sun, the ocean surface is completely frozen. Most   
   scientists think this ice crust is tens of miles thick.   
       
   "One opinion in the scientific community has been if the ice shell is thick,   
   that's bad for biology. That might mean the surface isn't communicating with   
   the underlying ocean," said Britney Schmidt, lead author of the Nature paper   
   and postdoctoral fellow at the Institute for Geophysics, University of Texas   
   at Austin. "Now, we see evidence that it's a thick ice shell that can mix   
   vigorously and new evidence for giant shallow lakes. That could make Europa   
   and its ocean more habitable."   
       
   http://www.jsg.utexas.edu/news/files/189099_cover_3_Thera_context_blend.jpg   
       
   Thera Macula (false color) is a region of likely active chaos production above   
   a large liquid water lake in the icy shell of Europa. [larger image] Schmidt   
   and her team focused on Galileo images of two roughly circular, bumpy features   
   on Europa's surface called chaos terrains. Based on similar processes seen on   
   Earth -- on ice shelves and under glaciers overlaying volcanoes -- they   
   developed a four-step model to explain how the features form. The model   
   resolves several conflicting observations. Some seemed to suggest the ice   
   shell is thick. Others suggest it is thin.   
       
   The recent analysis suggests chaos features on Europa's surface are formed by   
   mechanisms that involve significant exchange between the icy shell and the   
   underlying lake. This kind of "chaos" may provide a pathway for transferring   
   nutrients and energy between the surface and the vast global ocean already   
   thought to exist below the thick ice shell. Researchers believe this would   
   increase the potential for life there.   
       
   "This new understanding of processes on Europa would not have been possible   
   without the foundation of the last 20 years of observations over Earth's ice   
   sheets and floating ice shelves," said Don Blankenship, a co-author and senior   
   research scientist at the Institute for Geophysics, where he leads airborne   
   radar studies of Earth's ice sheets.   
       
   The authors have good reason to believe their model is correct. Still, because   
   the inferred lakes are several miles below the surface, the only true   
   confirmation of their presence would come from a future spacecraft mission   
   designed to probe the ice shell. Such a mission was rated as the second   
   highest priority flagship mission by the National Research Council's recent   
   Planetary Science Decadal Survey and is being studied by NASA.   
       
   For more images and a video animation of the findings, visit the University of   
   Texas at Austin. .   
       
   .   
   Production Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
       
   Galileo was the first spacecraft to directly measure Jupiter's atmosphere with   
   a probe and conduct long-term observations of the Jovian system. The probe was   
   the first to fly by an asteroid and discover the moon of an asteroid. NASA   
   extended the mission three times to take advantage of Galileo's unique science   
   capabilities, and it was put on a collision course into Jupiter's atmosphere   
   in September 2003 to eliminate any chance of impacting Europa.   
       
   The Galileo mission was managed by NASA's Jet Propulsion Laboratory in   
   Pasadena, Calif., for the agency's Science Mission Directorate.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.64   
    * Origin: NCS BBS (1:3828/7)