|
|||||
|
|
Large impact features on middle-sized icy satellites |
|
| Authors: | Jeffrey M Moore Paul M Schenk Erik Asphaug |
| Institution: | a Space Sciences Division, NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035-1000, USA b Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, TX 77058, USA c Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA d Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, Saint Louis, MO 63130, USA |
| 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, ∼350 km-diameter impact feature. We examine the antipodes of Odysseus, the putative ∼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. |
| Keywords: | Satellites of Saturn Satellites of Uranus Impact processes Surfaces satellite |
| 本文献已被 ScienceDirect 等数据库收录！ | |