Cassini’s Grand Finale is the gift that keeps on giving.  NASA deliberately crashed the spacecraft into Saturn’s atmosphere as it ran out of fuel in September, 2017.  But, the data it collected in its final maneuvers are still being read and deciphered.  Most recently, Cassini data revealed that Saturn’s five tiny ring moons are coated in, and shaped by the ring matter itself.  

In its final throws, Cassini performed a series of incredibly close flybys of Saturn, its rings and its ring moons.  Because they were so close, Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) was able to  create a spectral map of Pan, the innermost ring moon.  By analyzing spectra, VIMS determined the composition of materials found on all five tiny satellites. 

Pan, Atlas, Daphnis, Pandora and Epimetheus have porous surfaces.  That means that they’re made up of collected material that clung to the moons from the rings.  And, their odd shapes are the result.  Materials from the rings accretes around the moons’ equators, making them disc-shaped. “We found these moons are scooping up particles of ice and dust from the rings to form the little skirts around their equators,” Bonnie Buratti of JPL said. “A denser body would be more ball-shaped because gravity would pull the material in.”

The innermost moons have more ring material collected on them.  The outermost moons are also collecting icy particles from the plume on Enceladus.  That makes sense, as the outer “E” ring is composed of particles from Enceladus that are pulled in by Saturn’s gravity.  

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All of this information adds to what scientists know about how the universe and our solar system work.  Buratti added, “We’re seeing more evidence of how extremely active and dynamic the Saturn ring and moon system is.”

More findings from Cassini’s Grand Finale are expected to be revealed in the coming months.  



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