AGU: Geophysical Research Letters

 

Editors' Highlight

Pulses in Saturn's rings

In 2005, the Cassini spacecraft began a series of experiments to profile ring structure and measure the size distribution of particles in Saturn's rings. During these experiments, Cassini flew behind the ring plane and transmitted radio waves through ring particles to Earth. Scientists on Earth analyzed the signals' diffraction patterns to help determine properties of the rings. Thomson et al. (2007) studied these data and found that in limited regions of rings A and B (A and B lie close to the outside of Saturn's ring system), the diffraction pattern revealed the presence of fine-scale structures that are characterized by periodic radial variation in optical depth. They define specific periods of variation in optical depth for distinct regions of rings A and B. Given past research that suggests that the dynamic interplay of gravitational and collisional forces leads to the formation of viscous oscillations and gravity wakes in Saturn's rings, the authors speculated that the number density of ring particles contracts and relaxes to form periodic structures that affect the radio signals seen on Earth.

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