Cassini mission reveals the secrets of Saturn’s walnut-shaped ring moons

New study in in the high-ranking journal Science No 73/2019 from Mar 29, 2019 A new study of Saturn's small inner moons was published in the high-ranking journal Science . Images of Pan, Daphnis, Atlas, Pandora and Epimetheus, obtained by the Cassini spacecraft in winter 2016/17, show that several of these so-called "shepherd moons" exhibit huge ridges around their equators, giving them a very peculiar and impressing walnut-like shape (Fig. The report includes contributions of Freie Universität Berlin scientists Frank Postberg, Tilmann Denk, Nozair Khawaja, and Heike Rosenberg from the Department of Earth Sciences, Planetary Sciences and Remote Sensing. The "brims" of these highly irregularly-shaped small inner moons are probably created by tiny dust particles originating from the surrounding rings that are collected by the moons' small gravities over millions of years. This idea is substantiated further by the low densities of the inner moons and their porous surfaces inferred by the Cassini instruments. In addition to ice grains from the main rings that lie for the most part inside their orbits, the bright surfaces are also accumulating icy particles and water vapor ejected by the larger moon Enceladus from outside the main ring system (Fig. However, a mixture of organic materials and possibly iron again originating from the main ring system probably causes the reddish color seen on the inner moons.