Viscoelastic Modeling of Tidal Stresses on Satellites with an Enhanced SatStressGUI
Résumé
Icy and rocky satellites of our solar system display a diverse range of geological defor- mation on their surfaces. Some moons appear old and heavily cratered showing little evidence for recent tec- tonism while other moons are sparsely cratered and young, some showing ongoing geologic activity. The deformation can take the form of small cracks in the surface, large double ridges that can extend for thou- sands of kilometers, and mountain ranges that can reach heights of several kilometers. A key source of stress that can deform satellite surfaces is the diurnal tidal deformation of the moons as they orbit their par- ent planets. Other secular sources of global-scale stress include: volume change induced by the melting or freezing of a subsurface liquid layer, change in the orbital parameters of the moon, a tilt in the axis of ro- tation (obliquity), or rotation of the outer shell of the satellite relative to the rest of the body (nonsynchro- nous rotation or true polar wander).
We turn to computer modeling to correlate ob- served structural features to the possible stresses that created them. A variety of modeling programs exist and generally assume a thin ice shell and/or a multi- layered viscoelastic satellite. The program SatStress, which was developed by Zane Crawford and docu- mented in Wahr et al. [1], computes diurnal and non- synchronous rotation stresses on a satellite. It was later modified into a more user-friendly version with a graphic user interface (SatStressGUI) by Kay and Kat- tenhorn [2]. This implementation assumes a 4-layer viscoelastic body and is able to calculate stresses re- sulting from diurnal tides, nonsynchronous rotation (NSR), and ice shell thickening. Here we demonstrate our recent augmentations to SatStressGUI, including the ability to generate cycloid-style lineaments, calcu- late stresses resulting from obliquity, and more effi- ciently batch process data.
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