MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contact: Jane Platt (818) 354-0880
FOR IMMEDIATE RELEASE
February 18, 2000
VETERAN GALILEO VENTURES TO VAST VOLCANIC VISTAS
NASA's Galileo spacecraft is trying to go "three for three"
as it attempts its third and closest flyby of Jupiter's fiery
moon Io, the most volcanic body in the solar system.
The spacecraft will dip to only 200 kilometers (124 miles)
above Io's surface -- roughly the distance between Los Angeles and
San Diego -- at 6:32 a.m. Pacific Standard Time on Tuesday,
February 22. Galileo gathered a wealth of pictures and other
scientific information during its flybys of Io in October and
November of 1999.
"Io's volcanoes are so active that the moon's surface is
always changing, and with each flyby we get new and different
observations," said Dr. Torrence Johnson, Galileo project
scientist at NASA's Jet Propulsion Laboratory. "This time we
expect to be able to observe the effects of the eruptions we saw
in the October and November Io flybys."
The Io flybys represent a classic case of "no pain, no
gain," since Io orbits close to Jupiter in a region bombarded by
radiation from the huge planet's radiation belts. That radiation
can disrupt spacecraft systems or even knock out instruments, but
mission planners believe potential gains in scientific knowledge
outweigh the risks of the Io flybys. Nonetheless, the encounters
were planned near the end of Galileo's extended missions, when
the spacecraft has already returned volumes of pictures and
information from Jupiter and its moons.
"Although we gathered some great images and data during the
previous Io flybys, the radiation did cause some problems, and we
won't be surprised if that happens again this time," said Galileo
Project Manager Jim Erickson of JPL. "Galileo has already
survived more than twice the radiation it was designed to
withstand, so we're keeping our fingers crossed that it will
complete this encounter with flying colors."
Galileo engineers often say that the spacecraft has "lived
well past its warranty." Galileo entered orbit around Jupiter in
December 1995. It was originally assigned to spend two years
studying Jupiter, its moons and its magnetic environment. When
that original mission ended in December 1997, it was followed by a
two-year extended mission, which ended in January 2000. This Io
flyby is part of an additional extension, called the Galileo
Additional information about the Galileo mission is
JPL, a division of the California Institute of Technology in
Pasadena, manages the Galileo mission for NASA's Office of Space
Science, Washington, D.C.