TY - JOUR
T1 - Large impact features on middle-sized icy satellites
AU - Moore, Jeffrey M.
AU - Schenk, Paul M.
AU - Bruesch, Lindsey S.
AU - Asphaug, Erik
AU - McKinnon, William B.
N1 - Funding Information:
We especially thank Nadine Barlow and Beau Bierhaus for their careful reviews. Their comments and suggestions significantly improved the quality of this manuscript. This project began in 1986, at which time J.M.M. received a great deal of assistance from workers at the USGS in Flagstaff, whom he thanks. Also, due to the long gestation of this study, J.M.M. acknowledges support from NASA Planetary Geology and Geophysics Program (PGG) grants NSGW-1, NSGW-132, and NASA's Galileo Project. L.S.B. and E.A. were supported by NASA PGG grant NAG5-8914. P.M.S. and W.B.M. were supported by NASA PGG grants, and W.B.M. by a Uranus Data Analysis Program grant. We thank Peter Thomas for providing us with limb profiles of Tethys and Oberon. Thanks goes to Carrie Chavez for her help with manuscript preparation, Pam Engebretson for her help with figure preparation, and to Sue Selkirk and Dan Ball, who did the original figures over fifteen years ago.
PY - 2004/10
Y1 - 2004/10
N2 - 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.
AB - 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.
KW - Impact processes
KW - Satellites of Saturn
KW - Satellites of Uranus
KW - Surfaces, satellite
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U2 - 10.1016/j.icarus.2004.05.009
DO - 10.1016/j.icarus.2004.05.009
M3 - Article
AN - SCOPUS:4544243737
SN - 0019-1035
VL - 171
SP - 421
EP - 443
JO - Icarus
JF - Icarus
IS - 2
ER -