Cassini Tracks Raging Saturn Storm
- From: baalke@xxxxxxxxxxxxx
- Date: Tue, 29 Apr 2008 17:17:28 -0700 (PDT)
http://www.jpl.nasa.gov/news/news.cfm?release=2008-069
NASA Spacecraft Tracks Raging Saturn Storm
Jet Propulsion Laboratory
April 29, 2008
PASADENA, Calif. - As a powerful electrical storm rages on Saturn with
lightning bolts 10,000 times more powerful than those found on Earth,
the Cassini spacecraft continues its five-month watch over the
dramatic
events.
Scientists with NASA's Cassini-Huygens mission have been tracking the
visibly bright, lightning-generating storm--the longest continually
observed electrical storm ever monitored by Cassini.
Saturn's electrical storms resemble terrestrial thunderstorms, but on
a
much larger scale. Storms on Saturn have diameters of several thousand
kilometers (thousands of miles), and radio signals produced by their
lightning are thousands of times more powerful than those produced by
terrestrial thunderstorms.
Color images of the storm are available at: http://saturn.jpl.nasa.gov
and http://www.nasa.gov/cassini and http://ciclops.org .
Lightning flashes within the persistent storm produce radio waves
called
Saturn electrostatic discharges, which the radio and plasma wave
science
instrument first detected on Nov. 27, 2007. Cassini's imaging cameras
monitored the position and appearance of the storm, first spotting it
about a week later, on Dec. 6.
"The electrostatic radio outbursts have waxed and waned in intensity
for
five months now," said Georg Fischer, an associate with the radio and
plasma wave science team at the University of Iowa, Iowa City. "We saw
similar storms in 2004 and 2006 that each lasted for nearly a month,
but
this storm is longer-lived by far. And it appeared after nearly two
years during which we did not detect any electrical storm activity
from
Saturn."
The new storm is located in Saturn's southern hemisphere--in a region
nicknamed "Storm Alley" by mission scientists--where the previous
lightning storms were observed by Cassini. "In order to see the storm,
the imaging cameras have to be looking at the right place at the right
time, and whenever our cameras see the storm, the radio outbursts are
there," said Ulyana Dyudina, an associate of the Cassini imaging team
at
the California Institute of Technology in Pasadena, Calif.
Cassini's radio plasma wave instrument detects the storm every time it
rotates into view, which happens every 10 hours and 40 minutes, the
approximate length of a Saturn day. Every few seconds the storm gives
off a radio pulse lasting for about a tenth of a second, which is
typical of lightning bolts and other electrical discharges. These
radio
waves are detected even when the storm is over the horizon as viewed
from Cassini, a result of the bending of radio waves by the planet's
atmosphere.
Amateur astronomers have kept track of the storm over its five-month
lifetime. "Since Cassini's camera cannot track the storm every day,
the
amateur data are invaluable," said Fischer. "I am in continuous
contact
with astronomers from around the world."
The long-lived storm will likely provide information on the processes
powering Saturn's intense lightning activity. Cassini scientists will
continue to monitor Storm Alley as the seasons change, bringing the
onset of autumn to the planetâs southern hemisphere.
The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL, a division of
Caltech, manages the Cassini mission for NASA's Science Mission
Directorate, Washington, D.C. The Cassini orbiter and its two onboard
cameras were designed, developed and assembled at JPL. The imaging
team
is based at the Space Science Institute, Boulder, Colo. The radio and
plasma wave science team is based at the University of Iowa, Iowa
City.
------------------------------------------------------------------------
Media contacts: Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
carolina.martinez@xxxxxxxxxxxx
Preston Dyches 720-974-5859
Space Science Institute, Boulder, Colo.
media@xxxxxxxxxxx
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