Neutral cloud interaction with Saturn's main rings

The dense water cloud just outward of Saturn's main rings could strongly influence the surface composition of main ring constituents. Cassini pictures display brightening toward the outer edges of the main rings, suggesting that the outer edges have more icy material. We show that this enhanced brightening might not be a ring evolutionary feature, but a consequence of water molecules deposited from the dense neutral cloud emanating from Enceladus. We estimate the deposition rate and densities for water-group neutrals near the main rings, which could be important for determining the surface composition and chemistry of the ring particles.