The Source of Saturn's G Ring

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Science  03 Aug 2007:
Vol. 317, Issue 5838, pp. 653-656
DOI: 10.1126/science.1143964

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The origin of Saturn's narrow G ring has been unclear. We show that it contains a bright arc located 167,495.6 ± 1.3 km from Saturn's center. This longitudinally localized material is trapped in a 7:6 corotation eccentricity resonance with the satellite Mimas. The cameras aboard the Cassini spacecraft mainly observe small (1 to 10 micrometers) dust grains in this region, but a sharp decrease in the flux of energetic electrons measured near this arc requires that it also contain larger (centimeter- to meter-sized) bodies whose total mass is equivalent to that of a ∼100-meter-wide ice-rich moonlet. Collisions into these bodies may generate dust, which subsequently drifts outward to populate the rest of the G ring. Thus, the entire G ring could be derived from an arc of debris held in a resonance with Mimas.

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