Reorientation of icy satellites by impact basins

Abstract

Large impact basins are present on many of the icy satellites of the outer solar system. Assuming that their present‐day topography is uncompensated, such basins can cause significant poleward reorientations for slow‐rotating satellites. This reorientation may have been accompanied by transient large‐amplitude wobble. The largest basins on Tethys, Rhea and Titania are predicted to have caused reorientations of roughly 4°, 7° and 12°, respectively, resulting in global tectonic stresses up to ∼0.5 MPa. The potential anomalies associated with the basins can be up to one‐third of those expected for a hydrostatic, tidally‐ and rotationally‐deformed body, and may complicate interpretation of the satellite interior structure. Pluto and Charon, because of their slow rotation, are also likely to have undergone reorientation of 10–20° if they possess impact basins of comparable sizes to those of the Saturnian satellites.