“Perhaps this process is going on throughout the rings, and the largest ring particles are also accreting ring material around them. “A denser body would be more ball-shaped because gravity would pull the material in.” “We found these moons are scooping up particles of ice and dust from the rings to form the little skirts around their equators,” Buratti says. The porosity also helps explain their shape: Rather than being spherical, they are blobby and ravioli-like, with material stuck around their equators. Scientists also found the moon surfaces to be highly porous, further confirming that they were formed in multiple stages as ring material settled onto denser cores that might be remnants of a larger object that broke apart. The new research, from data gathered by six of Cassini’s instruments before its mission ended in 2017, is a clear confirmation that dust and ice from the rings accretes onto the moons embedded within and near the rings. “We’re seeing more evidence of how extremely active and dynamic the Saturn ring and moon system is.” Buratti led a team of 35 co-authors that published their work in the journal Science on 28 March 2019. “The daring, close flybys of these odd little moons let us peer into how they interact with Saturn’s rings,” says Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, California, United States.
The work paints a picture of the competing processes shaping these mini-moons. The closest-ever flybys by NASA’s Cassini spacecraft reveal that the surfaces of these unusual moons are covered with material from the planet’s rings – and from icy particles blasting out of Saturn’s larger moon Enceladus. New findings have emerged about five tiny moons nestled in and near Saturn’s rings. NASA’s Cassini spacecraft inspected the mini-moons Pan and Daphnis in the A ring Atlas at the edge of the A ring Pandora at the edge of the F ring and Epimetheus, which is bathed in material that fans out from the moon Enceladus.
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