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                 NASA Launches Project to Study Magnetic Fields

   by VOA News

   The U.S. space agency NASA has launched four spacecraft designed to
   study the magnetic relationship between the Earth and the sun.

   NASA launched the spacecraft late Thursday from Cape Canaveral,
   Florida, in an unmanned rocket.

   The spacecraft are expected to fly in pyramid formation in an oblong
   orbit, providing 3-D views of magnetic fields as they break and
   reconnect, releasing large amounts of energy.

   The energy releases are what cause the aurora borealis, or so-called
   "Northern Lights," and solar storms that can disrupt radio airwaves.

   Ocean on Jupiter

   In other space news, scientists using the Hubble Space Telescope
   confirmed that the Jupiter-orbiting moon Ganymede has an ocean beneath
   its icy surface, raising the prospects for life, NASA said Thursday.

   The finding resolves a mystery about the largest moon in the solar
   system after NASA's now-defunct Galileo spacecraft provided hints that
   Ganymede has a subsurface ocean during exploration of Jupiter and its
   moons from 1995 to 2003.

   Scientists told reporters on a conference call that it took some
   detective work to confirm the discovery.

   Like Earth, Ganymede has a liquid iron core that generates a magnetic
   field, though Ganymede's field is embedded within Jupiter's magnetic
   field. That sets up an interesting dynamic with telltale visuals --
   twin bands of glowing aurora around Ganymede's northern and southern
   polar regions.

   As Jupiter rotates, its magnetic field shifts, causing Ganymede's
   aurora to rock. Scientists measured the motion and found it fell short.
   Using computer models, they realized that a salty, electrically
   conductive ocean beneath the moon's surface was counteracting Jupiter's
   magnetic pull.

   "Jupiter is like a lighthouse whose magnetic field changes with the
   rotation of the lighthouse. It influences the aurora," said
   geophysicist Joachim Saur, with the University of Cologne in Germany.
   "With the ocean, the rocking is significantly reduced."

   Scientists ran more than 100 computer models to see if anything else
   could be having an impact on Ganymede's aurora.

   They also repeated the seven-hour, ultraviolet Hubble observations and
   analyzed data for both belts of aurora.

   "This gives us confidence in the measurement," Saur said.

   NASA Planetary Science Division Director Jim Green called the finding
   "an astounding demonstration."

   "They developed a new approach to look inside a planetary body with a
   telescope," Green said.

   Ganymede joins a growing list of moons in the outer solar system with
   subsurface water. On Wednesday, scientists reported that Saturn's moon
   Enceladus has hot springs beneath its icy crust. Other water-rich
   worlds include Jupiter moons Europa and Callisto.

   Scientists estimate the ocean is 60 miles (100 km) thick, 10 times
   deeper than Earth's oceans, and is buried under a 95-mile (150-km)
   crust of mostly ice.

   "It is one step further toward finding that habitable, water-rich
   environment in our solar system," said astronomer Heidi Hammel with the
   Washington-based Association of Universities for Research in Astronomy.

   Some material for this report came from Reuters.
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References

   1. http://www.voanews.com/content/reu-nasa-confirms-ocean-on-jupiter-moon/2678120.html