Spokes in Saturn's B Ring: Could Lightning be the Cause?

Spokes are narrow markings across Saturn's B ring, most likely caused by a cloud of micron sized particles intermittently lofted from the larger boulders comprising the ring. They were observed by the Voyagers, the Hubble Space Telescope, and more recently the Cassini spacecraft in orbit around Saturn since 2004. There are a number of suggestions to explain the triggering and subsequent evolution of spokes. In general, it is expected that spokes form due to sudden, short-lived changes in the plasma environment of the rings. Most recently, lightning in Saturn's atmosphere was suggested to trigger spokes, based on Cassini observations of field-aligned high-energy electron beams. In this talk we discuss the physic of the expected interactions of the rings with high energy electron beams, and show that, based on terrestrial examples, the expected amount of charge released in a lightning event could increase the surface charge density of the rings to sufficiently high values to trigger spokes.