NASA Technical Reports Server (NTRS) 19970022199: Cometary Nuclei a... | |
by NASA Technical Reports Server (NTRS) | |
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Prominent crater chains on Ganymede and Callisto are most | |
likely the impact scars of comets tidally disrupted by | |
Jupiter and are not secondary crater chains. We have | |
examined the morphology of these chains in detail in | |
order to place constraints on the properties of the | |
comets that formed them and the disruption process. In | |
these chains, intercrater spacing varies by no more than | |
a factor of 2 and the craters within a given chain show | |
almost no deviation from linearity (although the chains | |
themselves are on gently curved small circles). All of | |
these crater chains occur on or very near the Jupiter- | |
facing hemisphere. For a given chain, the estimated | |
masses of the fragments that formed each crater vary by | |
no more than an order of magnitude. The mean fragment | |
masses for all the chains vary by over four orders of | |
magnitude (W. B. McKinnon and P. M. Schenk 1995, Geophys. | |
Res. Lett. 13, 1829-1832), however. The mass of the | |
parent comet for each crater chain is not correlated with | |
the number of fragments produced during disruption but is | |
correlated with the mean mass of the fragments produced | |
in a given disruption event. Also, the larger fragments | |
are located near the center of each chain. All of these | |
characteristics are consistent with those predicted by | |
disruption simulations based on the rubble pile cometary | |
nucleus model (in which nuclei are composed on numerous | |
small fragments weakly bound by self-gravity), and with | |
those observed in Comet D/Shoemaker-Levy 9. Similar | |
crater chains have not been found on the other icy | |
satellites, but the impact record of disrupted comets on | |
Callisto and Ganymede indicates that disruption events | |
occur within the Jupiter system roughly once every 200 to | |
400 years. | |
Date Published: 2016-10-13 13:56:56 | |
Identifier: NASA_NTRS_Archive_19970022199 | |
Item Size: 41598348 | |
Language: english | |
Media Type: texts | |
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