Artist's representation of radio signals passing from the Cassini spacecraft, through Saturn's rings, and onto a satellite dish on earth.

Photojournal: PIA10232

January 31, 2008

Radio signals sent by NASA's Cassini spacecraft to Earth through Saturn's rings revealed the presence of highly unusual regular formations of densely grouped ring particles. The harmonic ring structure caused the radio signal frequency to separate into three distinct components. The observed frequencies determine the regular spacing to be as small as 100 meters (320 feet), the finest-scale ring structure observed so far.

The regularly spaced yellow grid depicts the harmonic structure in Saturn's inner Ring A, and the image on the bottom right shows an actual observed frequency pattern (spectrogram). Color represents the observed signal strength. The structure acts like an enormously extended natural diffraction grating that separates the signal frequency into the three distinct components shown. The frequencies determine the regular spacing of the diffraction grating, 160 meters (500 feet) in this case. The image of Saturn was taken with Cassini's cameras and is shown here to illustrate the occultation. For additional information on the radio observations see Saturn's Ring Rhythm #2.

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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radio science team is based at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit For more information on the radio science team visit The Cassini imaging team homepage is at .

Credit: NASA/JPL/Space Science Institute