The inner small satellites of Saturn: A variety of worlds

More than a dozen small (<150 km mean radius) satellites occupy distinct dynamical positions extending from within Saturn's classical rings to the orbit of Dione. The Cassini mission has gradually accumulated image and spectral coverage of these objects to the point where some generalizations on surface morphology may be made. Objects in different dynamical niches have different surface morphologies. Satellites within the main rings display equatorial ridges. The F-ring shepherding satellites show structural forms and heavily cratered surfaces. The co-orbitals Janus and Epimetheus are the most lunar-like of the small satellites. Satellites occupying libration zones (Trojan satellites) have deep covering of debris subject to downslope transport. Small satellites embedded in ring arcs are distinctively smooth ellipsoids that are unique among small, well-observed Solar System bodies and are probably relaxed, effectively fluid equilibrium shapes indicative of mean densities of about 300 kg m−3.