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Jan 3, 2000: NASA's Galileo spacecraft has kicked off
the new year with a successful flyby of Jupiter's icy moon Europa.
The spacecraft swooped past Europa at an altitude of 351 kilometers
(218 miles) at 10:38 a.m. Pacific Standard Time on January 3,
2000.
JPL reports that the spacecraft is operating normally, and it
appears that its instruments have completed their observations
of the magnetic fields and charged particles around Europa. These
observations were designed to detect any magnetic disturbances
that may occur because of electrical currents set up in an ocean
that may lie beneath Europa's icy crust. The prospect of a liquid ocean
on Europa is intriguing, since water is one of the ingredients
essential for life.
Above: This alluring color image
of Europa's surface was produced by combining low resolution
color data with higher resolution mosaics recorded during three
separate flybys and covers about 120 by 150 miles. The eerie
terrain of grooved linear ridges and crustal plates which seem
to have broken apart and rafted into new positions could indicate
subsurface water or slush. [more
information]
Because Galileo passed behind Europa during the flyby,
its radio signal to Earth was blocked for a while. Scientists
took advantage of this situation by studying the way the radio
signal changed as the spacecraft entered this "silent zone."
These radio science experiments teach us more about Europa's
ionosphere -- the region of charged particles surrounding the
moon -- and any possible atmosphere.
Observations of three of Jupiter's small natural satellites --
Amalthea, Thebe, and Metis -- are planned for Galileo later on
Jan. 3, with observations of Jupiter's volcanic moon Io on the
spacecraft's agenda for the early morning of Jan. 4. All data
gathered during this flyby are being stored on Galileo's onboard
tape recorder. They will be transmitted to Earth during the coming
weeks.
Above:The potato-shaped inner moons
of Jupiter are lined-up in this mosaic "family portrait"
of these tiny Jovian satellites. Left to right in increasing
order of distance from Jupiter are Metis (longest dimension 37
miles), Adrastea (12 miles), Amalthea (154 miles), and Thebe
(72 miles). All these moons orbit in the zone between Io and
Jupiter's rings, are bombarded by high-energy ions within the
Jovian magnetosphere. More
information.
NASA Headquarters has agreed in principle to extend the Galileo
mission past its planned January 31 finale. Details of funding
and itinerary for the new extended mission, to be called the
Galileo Millennium Mission, must still be resolved. Monday's
Europa encounter took place January 3, 2000, and is technically
still part of the current, extended Galileo Europa Mission. Another
Io flyby is planned for February 22, with flybys of Ganymede
on May 30 and December 28, and joint observations of Jupiter
with the Cassini spacecraft in December 2000.
Galileo has been orbiting Jupiter and its moons since December
1995, beaming to Earth unprecedented images and other information.
JPL, a division of the California Institute of Technology, Pasadena,
CA, manages the Galileo mission for NASA's Office of Space Science,
Washington, DC.
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