CONTACT: GARY GALLUZZO
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Iowa City IA 52242
(319) 384-0009; fax (319) 384-0024
Release: Oct. 5, 2001
UI researcher detects volcanic smoke plume at Jupiter's moon, Io
IOWA CITY, Iowa -- In the first observation of its kind, University of Iowa
physicist Louis A. Frank recently detected freshly released particles from
a volcano at Jupiter's moon, Io, using instruments aboard NASA's Galileo spacecraft.
Space scientists, including Frank, were using the spacecraft to examine
Io when a volcano at the moon's surface on Aug. 6 unexpectedly emitted the
tallest volcanic smoke plume yet seen. During the pre-planned fly-by of Io,
scientists captured images of the plume using Galileo's cameras and identified
the site of the volcanic eruption using an infrared mapping instrument. Frank,
principal investigator on the Plasma Science Instrument, had an opportunity
to collect a sample of the volcanic plume -- thought to be composed of flakes
of sulfur dioxide -- as it rose some 300 miles above the surface while Galileo
sped past at about 120 miles above Io.
He says that by studying the impact of the particles with the plasma instrument,
he and his colleagues will be able to learn more about the temperature and
speed of the gas.
"It is simply marvelous that we were able to grab some of the strange
snow flakes which were formed by the enormous flow of gas from this volcano,"
The discovery was surprising because no active volcanic plumes had been
observed in the high-latitude regions of Io during the first five years of
the Galileo spacecraft's investigation at Jupiter and its moons. As the August
fly-by approached, scientists were aware that a previous emission had occurred
at the site of another volcano about seven months earlier. However, that eruption
gave no hint of the August activity or even that a second volcano was active
in the region. Frank says that the discovery was "totally unexpected"
and leads scientists to wonder what they may find when Galileo encounters
Io on Oct. 16 before making its sixth and final fly-by of Io in January 2002.
In previously published papers on Io, Frank and UI colleague Donald Gurnett,
principal investigator on the Plasma Wave Instrument, reported that Jupiter's
plasma, or electrically charged gas, flows past Io and creates a plasma wake,
similar to the watery wake caused by a boat. They also found that a corresponding
empty area on Io's backside is filled with dense, relatively cool ions of
oxygen, sulfur and sulfur dioxide shooting out from Io's volcanic surface.
In addition to Frank and Gurnett, UI Regent Distinguished Professor of Physics
and Astronomy James A. Van Allen continues to serve the Galileo Project as
an interdisciplinary scientist.
Galileo was launched from the Space Shuttle on Oct. 18, 1989 and, after
a journey of 2.3 billion miles, arrived at Jupiter on Dec. 7, 1995. The Galileo
Probe entered Jupiter's atmosphere, while the Galileo spacecraft continued
on its mission to investigate four of Jupiter's larger moons. The Jet Propulsion
Laboratory (JPL), a division of the California Institute of Technology in
Pasadena, manages Galileo for NASAs Office of Space Science, Washington,
D.C. Additional information about the mission is available online at: http://www.jpl.nasa.gov/.