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Europa's surface shows signs of extension, which is revealed as lithospheric dilation expressed along ridges, dilational bands and ridged bands. Ridges, the most common tectonic feature on Europa, comprise a central crack flanked by two raised banks a few hundred meters high on each side. Together these three classes may represent a continuum of formation. In Tufts' Dilational Model ridge formation...
Observations of Enceladus have revealed active jets of material erupting from cracks on its south polar surface. It has previously been proposed that diurnal tidal stress, driven by Enceladus’ orbital eccentricity, may actively produce surface movement along these cracks daily and thus may regulate when eruptions occur. Our analysis of the stress on jet source regions identified in Cassini ISS images...
Spectral maps of Mimas’ daytime thermal emission show a previously unobserved thermal anomaly on Mimas’ surface. A sharp V-shaped boundary, centered at 0°N and 180°W, separates relatively warm daytime temperatures from a cooler anomalous region occupying low- to mid-latitudes on the leading hemisphere. Subsequent observations show the anomalous region is also warmer than its surroundings at night,...
Given the non-spherical shape of Enceladus [Thomas et al., 2007], the satellite will experience gravitational torques that will cause it to physically librate as it orbits Saturn. Physical libration would produce a diurnal oscillation in the longitude of Enceladus’ tidal bulge, which could have a profound effect on the diurnal tidal stresses experienced by the surface of the satellite. Although Cassini...
Tectonic patterns on Europa are influenced by tidal stress. An important well-recognized component is associated with the orbital eccentricity, which produces a diurnally varying stress as Jupiter's apparent position in Europa's sky oscillates in longitude. Cycloidal lineaments seem to have formed as cracks propagated in this diurnally varying stress field. Maps of theoretical cycloid patterns capture...
Cycloidal crack patterns on Europa are influenced by tides induced by orbital eccentricity, which in turn is driven by the Laplace orbital resonance. Their shapes potentially record the location of their formation (relative to the direction of Jupiter), as well as the parameters of crack formation. Hoppa et al. [Hoppa, G., Tufts, B.R., Greenberg, R., Geissler, P., 1999a. Icarus 141, 287–298] modeled...
Using photoclinometry, topographic profiles across europan ridges have been produced. These profiles allow the identification of bulges in the terrain adjacent to the ridges. The bulges are assumed to have been produced by flexure of the elastic lithosphere due to the load of the ridges, which lie along cracks in the crust. The distance from the crack to these “fore-bulges” depends on the thickness...
Asteroid Ida's satellite Dactyl was observed over 512hr by the Galileo spacecraft imaging system. The observed motion fits a family of orbits parameterized by the mass of Ida. We have tested the stability of these orbits by numerically integrating motion about a realistically shaped model for Ida. Those with pericenter distanceq≲ 65 km (corresponding to Ida's density ≳ 3.1 g cm −3 ) are unstable...
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