December 2000	Win Prizes ! Free Music ! Free Tablature ! Win Prizes ! Free Music ! Free Tablature !

Jupiter moon may have a saltwater ocean

 
                   SAN FRANCISCO, California
                   (Reuters) -- Scientists studying data
                   sent back to Earth from NASA's
                   Galileo spacecraft have concluded that
                   Jupiter's largest moon, Ganymede, may
                   possess a huge salt-water ocean
                   beneath its crusty surface.

                   Galileo probe data on two other Jovian
                   moons -- Europa and Callisto -- has already indicated that they probably have
                   subsurface water, a key building block for life.

                   Now, Ganymede -- which is larger than Mercury or Pluto -- also looks likely to
                   be concealing a thick layer of melted, salty water beneath its icy crust,
                   researchers told a meeting of the American Geophysical Union here Saturday.

                   Margaret Kivelson of the University of
                   California-Los Angeles said that magnetic
                   readings taken by the Galileo craft during close
                   approaches in May 2000 and earlier were "highly
                   suggestive" that a salty, liquid ocean existed there.

                   "It would need to be something more electrically
                   conductive than solid ice," she said, adding that a
                   melted layer of water several kilometers or miles thick, beginning within 120
                   miles of Ganymede's surface would fit the data if it were about as salty as
                   Earth's oceans.

                   Other scientists studying readings from an infrared spectrometer to identify
                   surface materials on Ganymede said portions of the moon appear to have types
                   of salt minerals that would have been left behind by exposure of salty water
                   near or on the surface.

                   "They are similar to the hydrated salt minerals we see on Europa, possibly the
                   result of brine making its way to the surface by eruptions or through cracks,"
                   said Thomas McCord, a geophysicist at the University of Hawaii, Honolulu.

                   That hypothesis is also bolstered by new, high-resolution images of Ganymede
                   sent back by Galileo, which hint that water or slushy ice may have surfaced
                   through the fractured crust to create smooth areas in between separated areas
                   of crust.

                   Dr. Dave Stevenson of the California Institute of Technology said natural
                   radioactivity in Ganymede's rocky interior should provide enough heating to
                   maintain a stable layer of liquid water between two layers of ice, about 90 to
                   120 miles below the surface.

                   "I would have been surprised if Ganymede had not had an ocean, but the issue
                   of whether it's there is different than the issue of whether you can expect to see
                   it clearly in the data," Stevenson said.