PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Jane Platt
FOR IMMEDIATE RELEASE
February 19, 1997
GALILEO RETURNS TO EUROPA FOR ANOTHER CLOSE LOOK
NASA's Galileo spacecraft will make an encore appearance at
Jupiter's icy moon, Europa, on Thursday, Feb. 20, marking the
closest planned Europa flyby of the initial two-year mission.
The encounter will be Galileo's closest flyby yet of Europa.
The craft will swoop past the Jovian moon at an altitude of 580
kilometers (360 miles) on Thursday, Feb. 20, at 9:06 a.m. Pacific
time (12:06 p.m. Eastern time).
Galileo made its first pass of Europa in December 1996,
revealing remarkable detail of that moon's terrain. This week's
flyby will look at other areas of Europa's surface, which is
covered by ice and a series of criss-crossed, dark lines. Europa
holds great fascination for scientists because of the possibility
that liquid oceans may be hidden underneath the icy surface. The
presence of liquid water would boost the odds that Europa could
host some form of life.
"I think this flyby may provide additional clues regarding
the prospect of liquid water oceans on Europa," said Galileo
Mission Director Bob Mitchell.
With its diameter of 3,138 kilometers (1,946 miles), Europa
is just slightly smaller than Earth's moon. Because the geometry
of the upcoming flyby will be somewhat different from the path
taken by Galileo's previous Europa encounter, it will yield data
and images of different portions of the moon.
"This position will allow for high resolution of different
terrain," said Mitchell. "It will help us learn more about
Europa's structure and surface and how the surface was formed."
The current Europa encounter phase began on Sunday, Feb. 16,
and will continue through Saturday, Feb. 22. The spacecraft has
already begun returning real-time encounter data, with recorded
data scheduled to be transmitted to Earth beginning on the
evening of Saturday, Feb. 22 (Pacific time).
This encounter will include the return of magnetospheric
measurements from Europa's vicinity. Other science highlights
will include the study of surface features of Europa's lineated
regions, images of two other, smaller Jovian moons, Thebe and
Amalthea, and studies of such Jovian atmospheric features as the
south equatorial belt-zone boundary and the aurora borealis.
This flyby provides a period of radio occultation, when
Europa crosses between Earth and Galileo, temporarily cutting off
the spacecraft's radio signal. This affords a prime opportunity
for Galileo to study atmospheric data just before and after radio
contact is lost, when the signal passes through the Europa's
"As the fifth encounter in Galileo's series of 10 flybys,
this marks the approximate halfway point for this series, which
began in June 1996," said Galileo Project Manager Bill O'Neil.
"It's been eight months since then, and it will be another eight
months before the series' final encounter."
A third Europa flyby is planned for Nov. 6, 1997, and JPL
has asked NASA to extend the Galileo mission by two years to
include eight more Europa flybys and ultimately a flyby of Io.
The proposed extended mission might be shortened if the
spacecraft's operations were to deteriorate as a result of its
continuous exposure to Jupiter's extreme radiation environment.
"NASA has assured us that the extended mission will be
funded," said O'Neil. "The $30 million needed for the extension
will come from within the existing NASA budget, enabled by cost
savings due to improved efficiencies in JPL's spacecraft tracking
and mission operations."
The 2,223-kilogram (2-1/2 ton) Galileo orbiter spacecraft
was launched aboard Space Shuttle Atlantis on October 18, 1989.
JPL manages the Galileo Project for NASA's Office of Space
Science, Washington, D.C.
Additional information on the Galileo mission and its
results can be found on the World Wide Web at