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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L19203, doi:10.1029/2007GL030798, 2007

Reorientation of icy satellites by impact basins

F. Nimmo

Department of Earth and Planetary Sciences, University of California, Santa Cruz, California, USA


I. Matsuyama

Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, D.C., USA


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.

Received 29 May 2007; accepted 5 July 2007; published 3 October 2007.

Keywords: rotational dynamics.

Index Terms: 5417 Planetary Sciences: Solid Surface Planets: Gravitational fields (1221); 5422 Planetary Sciences: Solid Surface Planets: Ices; 5450 Planetary Sciences: Solid Surface Planets: Orbital and rotational dynamics (1221); 6280 Planetary Sciences: Solar System Objects: Saturnian satellites; 6290 Planetary Sciences: Solar System Objects: Uranian satellites.

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Citation: Nimmo, F., and I. Matsuyama (2007), Reorientation of icy satellites by impact basins, Geophys. Res. Lett., 34, L19203, doi:10.1029/2007GL030798.