Cassini Reveals Saturn's Eerie-Sounding Radio Emissions

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Gary Galluzzo (319) 384-0009
University of Iowa, Iowa City

News Release: 2005-119 July 25, 2005

Cassini Reveals Saturn's Eerie-Sounding Radio Emissions

Saturn's radio emissions could be mistaken for a Halloween
sound track.

That's how two researchers describe their recent findings,
published in the July 23 issue of the Geophysical Research
Letters. Their paper is based on data from the Cassini
spacecraft radio and plasma wave science instrument. The
study investigates sounds that are not just eerie, but also
descriptive of a phenomenon similar to Earth's northern
lights.

"All of the structures we observe in Saturn's radio spectrum
are giving us clues about what might be going on in the
source of the radio emissions above Saturn's auroras," said
Dr. Bill Kurth, deputy principal investigator for the
instrument. He is with the University of Iowa, Iowa City.
Kurth made the discovery along with Principal Investigator
Don Gurnett, a professor at the University. "We believe that
the changing frequencies are related to tiny radio sources
moving up and down along Saturn's magnetic field lines."

Samples of the resulting sounds can be heard at
www.nasa.gov/cassini , http://saturn.jpl.nasa.gov
and http://www-pw.physics.uiowa.edu/cassini/ .

The radio emissions, called Saturn kilometric radiation, are
generated along with Saturn's auroras, or northern and
southern lights. Because the Cassini instrument has
higher resolution compared to a similar instrument on NASA's
Voyager spacecraft, it has provided more detailed information
on the spectrum and the variability of radio emissions. The
high-resolution measurements allow scientists to convert the
radio waves into audio recordings by shifting the frequencies
down into the audio frequency range.

The terrestrial cousins of Saturn's radio emissions were
first reported in 1979 by Gurnett, who used an instrument on
the International Sun-Earth Explorer spacecraft in Earth
orbit. Kurth said that despite their best efforts, scientists
still haven't agreed on a theory to fully explain the
phenomenon.

They will get another chance to solve the radio emission
puzzle beginning in mid-2008 when Cassini will fly close to,
or possibly even through, the source region at Saturn.
Gurnett said, "It is amazing that the radio emissions from
Earth and Saturn sound so similar."

Other contributors to the paper include University of Iowa
scientists George Hospodarsky and Baptiste Cecconi; Mike
Kaiser (currently at Goddard Space Flight Center, Greenbelt,
Md.); French scientists Philippe Louarn, Philippe Zarka and
Alain Lecacheux; and Austrian scientists Helmut Rucker and
Mohammed Boudjada.

Cassini, carrying 12 scientific instruments, on June 30, 2004,
became the first spacecraft to orbit Saturn. It is conducting
a four-year study of the planet, its rings and many moons. The
spacecraft carried the Huygens probe, a six-instrument
European Space Agency probe that landed on Titan, Saturn's
largest moon, in January 2005.

The Cassini-Huygens mission is a cooperative project of NASA,
the European Space Agency and the Italian Space Agency. The
Jet Propulsion Laboratory, a division of the California
Institute of Technology in Pasadena, manages the
Cassini-Huygens mission for NASA's Science
Mission Directorate, Washington. JPL designed, developed
and assembled the Cassini orbiter. The radio and plasma wave
science team is based at the University of Iowa, Iowa City.

For information on the Cassini mission visit
http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

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