Dwayne C. Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov
Jia-Rui Cook
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0850
jccook@jpl.nasa.gov
Nancy Neal-Jones/Elizabeth Zubritsky
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039/301-614-5438
nancy.n.jones@nasa.gov/elizabeth.a.zubritsky@nasa.gov
RELEASE: 11-151
CASSINI SPACECRAFT AND GROUND TELESCOPE SEE VIOLENT SATURN STORM
WASHINGTON -- NASA's Cassini spacecraft and a European Southern
Observatory ground-based telescope tracked the growth of a giant
early-spring storm in Saturn's northern hemisphere so powerful it
stretches around the entire planet. The rare storm has been wreaking
havoc for months and shot plumes of gas high into the planet's
atmosphere.
Cassini's radio and plasma wave science instrument first detected the
large disturbance, and amateur astronomers tracked its emergence in
December 2010. As it rapidly expanded, its core developed into a
giant, powerful thunderstorm. The storm produced a 3,000-mile-wide
(5,000-kilometer-wide) dark vortex, possibly similar to Jupiter's
Great Red Spot, within the turbulent atmosphere.
The dramatic effects of the deep plumes disturbed areas high up in
Saturn's usually stable stratosphere, generating regions of warm air
that shone like bright "beacons" in the infrared. Details are
published in this week's edition of Science Magazine.
"Nothing on Earth comes close to this powerful storm," says Leigh
Fletcher, the study's lead author and a Cassini team scientist at the
University of Oxford in the United Kingdom. "A storm like this is
rare. This is only the sixth one to be recorded since 1876, and the
last was way back in 1990."
This is the first major storm on Saturn observed by an orbiting
spacecraft and studied at thermal infrared wavelengths, where
Saturn's heat energy reveals atmospheric temperatures, winds and
composition within the disturbance.
Temperature data were provided by the Very Large Telescope (VLT) on
Cerro Paranal in Chile and Cassini's composite infrared spectrometer
(CIRS) operated by NASA's Goddard Space Flight Center in Greenbelt,
Md.
"Our new observations show that the storm had a major effect on the
atmosphere, transporting energy and material over great distances,
modifying the atmospheric winds -- creating meandering jet streams
and forming giant vortices -- and disrupting Saturn's slow seasonal
evolution," said Glenn Orton, a paper co-author, based at NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, Calif.
The violence of the storm -- the strongest disturbances ever detected
in Saturn's stratosphere -- took researchers by surprise. What
started as an ordinary disturbance deep in Saturn's atmosphere
punched through the planet's serene cloud cover to roil the high
layer known as the stratosphere.
"On Earth, the lower stratosphere is where commercial airplanes
generally fly to avoid storms which can cause turbulence," says
Brigette Hesman, a scientist at the University of Maryland in College
Park who works on the CIRS team at Goddard and is the second author
on the paper. "If you were flying in an airplane on Saturn, this
storm would reach so high up, it would probably be impossible to
avoid it."
Other indications of the storm's strength are the changes in the
composition of the atmosphere brought on by the mixing of air from
different layers. CIRS found evidence of such changes by looking at
the amounts of acetylene and phosphine, both considered to be tracers
of atmospheric motion. A separate analysis using Cassini's visual and
infrared mapping spectrometer, led by Kevin Baines of JPL, confirmed
the storm is very violent, dredging up larger atmospheric particles
and churning up ammonia from deep in the atmosphere in volumes
several times larger than previous storms. Other Cassini scientists
are studying the evolving storm, and a more extensive picture will
emerge soon.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. The mission is
managed by JPL for NASA's Science Mission Directorate in Washington.
The European Southern Observatory in Garching, Germany operates the
VLT in Chile.
For information about Cassini, visit:
-end-
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