By Ron Cowen
The Cassini spacecraft has caught a thief on camera. Images show Saturn’s moon Prometheus stealing particles from the planet’s F ring. This multistranded, kinked ring is flanked by 102-kilometer-wide Prometheus and another moon, Pandora.
The thievery and the detailed view of kinks in the F ring were recorded by Cassini on Oct. 29, 2004, when it was 782,000 km from the moon. NASA released the images on Dec. 3.
The nearly 2-hour sequence of 44 pictures shows Prometheus pulling particles from the F ring while appearing connected to the ring by a faint streak of material. The moon’s elongated orbit intersects the F ring, and scientists have long suspected that it picked up ring particles with each transit, notes Cassini researcher Carolyn Porco of the Space Science Institute in Boulder, Colo. Computer models and observations suggest that the moon’s gravity—as well as Pandora’s—deflects particles from their normal orbits and can generate large waves or knots within the ring.
The interaction between Prometheus and the F ring may provide a better understanding of the interplay between other Saturnian moons and rings.
