PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Jane PlattDecember 16, 1997
FOR IMMEDIATE RELEASE
CLOSEST EUROPA FLYBY MARKS START OF GALILEO MISSION "PART II"
NASA's Galileo spacecraft today successfully made its
closest-ever flyby of Jupiter's icy moon Europa, marking the
start of an extended mission that will focus on new and
tantalizing scientific questions raised by its just-completed,
highly successful two-year primary mission.
"Galileo has earned a place in history as the first
mission to orbit an outer planet," said Dr. Wesley T. Huntress,
Jr., NASA's associate administrator for space science,
Washington, DC. "Galileo already has returned a wealth of new
information in its two-year scientific exploration of Jupiter's
atmosphere and system of moons. But the best yet may still be
ahead of us as Galileo continues its mission at Jupiter with a
focus on the moons Europa and Io in the next two years."
Galileo dipped over Europa at an altitude of only 200 kilometers
(124 miles), with the signal received on Earth at 4:49 a.m. PST.
This was the first encounter of the Galileo Europa mission, which
began formally on Dec. 8, just following the end of Galileo's
primary mission. The Galileo Europa mission will study Jupiter's
icy satellite in detail in hopes of shedding more light on the
intriguing prospect that liquid oceans may lie under Europa's ice
New images released today from Galileo's Europa encounter of Nov.
6 show more evidence that the moon has been subjected to intense
geological deformation. The pictures show a mottled region of dark
and splotchy terrain that scientists say represents some of the most
recent geologic activity on Europa. It is believed the mottled
appearance was created when chaotic areas of the bright, icy crust
broke apart and exposed darker material underneath. The new images
also show a smooth, gray band where the Europan crust has been
fractured, separated, and filled in with material from the interior.
Numerous isolated mountains or "massifs" are visible.
The new images represent a small portion of the 1,800 images
obtained during Galileo's primary mission, including hundreds of
high-resolution images of Jupiter's moons. The images and other
information gathered by Galileo's science instruments have
dramatically revised our knowledge of Jupiter and its moons,
according to mission scientists.
The Galileo Europa mission is designed to follow up on
these discoveries and will include eight consecutive Europa
flybys through February 1999, followed by four Callisto flybys
and one or two Io encounters in late 1999, provided the
spacecraft remains healthy.
"The Galileo Europa mission really builds upon the
success of the prime mission which has forced us to re-think many
of our perceptions of the Jovian system," said Galileo project
scientist Dr. Torrence Johnson. "We've acquired a tremendous
pool of knowledge about Jupiter, its magnetosphere and its four
The key findings of Galileo's primary mission include:
"We look forward to providing even more fascinating
science results over the next two years," said newly appointed
Galileo Europa mission project manager Bob Mitchell of NASA's Jet
Propulsion Laboratory (JPL), Pasadena, CA.
- The existence of a magnetic field on Jupiter's largest
- The discovery of volcanic ice flows and melting or
"rafting" of ice on the surface that supports the premise of
liquid oceans underneath at some point in Europa's history;
- The observation of water vapor, lightning and aurora on
- The discovery of an atmosphere of hydrogen and carbon
dioxide on the moon Callisto;
- The presence of metallic cores in Europa, Io and Ganymede
and the lack of evidence of such a core in Callisto;
- Evidence of very hot volcanic activity on Io and observations
of dramatic changes compared to previous observations and even
during the period of Galileo's observations.
JPL manages the Galileo mission for NASA's Office of
Space Science, Washington, DC. The new images shown at today's
briefing are available on the Galileo Internet home page at the
following URL: http://www.jpl.nasa.gov/galileo/
Members of the Galileo mission will answer questions from
the public during a Galileo WebChat on Wednesday, Dec. 17 from 6
to 9 p.m. EST, at URL: http://www.jpl.nasa.gov/galileo/chat/