Galileo moves on to Europa
December 16, 1997
Web posted at: 10:40 p.m. EST (0340 GMT)
(CNN) -- NASA's Galileo flew about 125 miles over Jupiter's moon Europa on Tuesday, marking the beginning of the spacecraft's next phase.
Galileo, which has spent the past two years studying Jupiter and its four largest moons, will now concentrate on Europa's icy crust. The moon is of great interest because of hints that it may have a huge ocean of water beneath its surface.
Scientists are fascinated by the blister-like structures on Europa's rough surface. They say the blisters could have been formed by a process like the kind in a lava lamp.
The Europa mission began December 8 after the end of Galileo's two-year primary mission. Scientists hope the second phase of the mission will be as fruitful as the first, which documented:
- The existence of a magnetic field on Ganymede, the biggest moon of Jupiter.
- Discovery of volcanic ice flows and melting of ice on the surface of Europa that support the premise of liquid oceans underneath.
- Water vapor, lightning and aurora on Jupiter.
- Metallic cores in Europa, Io and Ganymede, but no such core in Callisto.
- An atmosphere of hydrogen and carbon dioxide on Callisto.
- Evidence of volcanic activity on Io.
Image of the moon Io taken on an orbit in February
NASA is already studying some 1,800 images sent back to Earth during Galileo's primary mission, including high-resolution pictures of the biggest Jovian moons.
The Europa mission is designed to follow up on previous discoveries and will include eight consecutive fly-bys through February 1999, followed by four of the moon Callisto and one or two of Io in 1999.
"The Galileo Europa mission really build upon the success of the prime mission, which has forced us to rethink many of our perceptions of the Jovian system," said Galileo project scientist Torrence Johnson.
"Jupiter dished up some nice juicy surprises," he said.
After the current mission looks at Europa, it will go on to look at Io and Callisto late next year.
Correspondent Rick Lockridge and Reuters contributed to this report.