The spiral wave model, or “rotating searchlight” model, that can explain the time-lagged periodicity observed in the electron measurements from Cassini. Credit: Carbary, 2015, Figure 8
Source: Journal of Geophysical Research: Space Physics

In 2017, the Cassini spacecraft ended its orbital tour of Saturn, its moons, and its space environment. At the end, as it came closer and closer to Saturn for its final plunge into the atmosphere, it collected a unique set of data that is just beginning to analyzed for new insights about how this planet works. Carbary et al. [2017] use the very latest, and last, Cassini data available to continue an ongoing investigation of the mysterious periodicities in Saturn’s magnetosphere. They conclude two important findings: the periodicity of the summer hemisphere of the planet seems to dominate the magnetospheric periodicity, and the periodicity as a function of radial distance can be explained by “a simple version of a rotating searchlight model.” It is the latest chapter in a long debate about an important mystery of Saturn’s space environment.

Citation: Carbary, J. F., Mitchell, D. G., Kollmann, P., Krupp, N., & Roussos, E. [2017]. Energetic electron periodicities during the Cassini grand finale. Journal of Geophysical Research: Space Physics, 122.

—Mike Liemohn, Editor-in-Chief, JGR: Space Physics

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