Article,
Large impact features on middle-sized icy satellites
Icarus, 171 (2): 421--443 (2004)
Abstract
All of the large impact features of the middle-sized icy satellites
of Saturn and Uranus that were clearly observed by the Voyager spacecraft
are described. New image mosaics and stereo-and-photoclinometrically-derived
digital elevation models are presented. Landforms related to large
impact features, such as secondary craters and possible antipodal
effects are examined and evaluated. Of the large impacts, Odysseus
on Tethys appears to have had the most profound effect on its "target"
satellite of any of the impact features we examined. Our modeling
suggests that the Odysseus impact may have caused the prompt formation
of Ithaca Chasma, a belt of tectonic troughs that roughly follow
a great circle normal to the center of Odysseus, although other hypotheses
remain viable. We identify probable secondary cratering from Tirawa
on Rhea. We attribute a number of converging coalescing crater chains
on Rhea to a putative, possibly relatively fresh, similar to 350
km-diameter impact feature. We examine the antipodes of Odysseus,
the putative similar to 350 km-diameter Rhean impact feature, and
Tirawa, and conclude that evidence from Voyager data for damage from
seismic focusing is equivocal, although our modeling results indicate
that such damage may have occurred. We propose a number of observations
and tests for Cassini that offer the opportunity to differentiate
among the various explanations and speculations reviewed and evaluated
in this study. Published by Elsevier Inc.
Tags
- callisto;
- ejecta;
- europa;
- ganymede;
- history;
- hydrodynamics;
- internal
- particle
- photometry
- saturn
- simulations;
- structure;
- system;
