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Fragmentation of ice by low velocity impact

Lange, Manfred A. and Ahrens, Thomas J. (1981) Fragmentation of ice by low velocity impact. In: Proceedings of the Lunar and Planetary Science Conference. Lunar and Planetary Institute . Vol.2. Pergamon Press , New York, NY, pp. 1667-1687. ISBN 0080280749. https://resolver.caltech.edu/CaltechAUTHORS:20150213-092357505

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Abstract

Low velocity impact experiments (0.14 to l km/s) carried out in polycrystalline water ice targets at 257 and 81 K resulted in interactions which can be assigned to four fragmentation classes, cratering, erosion, disruption, and total fragmentation. Specific kinetic energies for the transitions between these classes range from l x 10^5 to 7 x 10^5 ergs/g for 81 K ice and from 3 x 10^5 to ~ 2 x 10^6 ergs/g for 257 K ice. These values are about one to two orders of magnitude below those for silicate rocks. The mass vs. cumulative number distribution of fragments in our experiments can be described by a simple power law, similar to that observed in fragmented rocks in both the laboratory and in nature. The logarithmic slopes of cumulative number vs. fragment weight vary between - 0.9 and - 1.8 decreasing with increasing projectile energy and are approximately independent of target temperature. The shapes of fragments resulting from erosion and disruption of ice targets are significantly less spherical for 257 K targets than for 81 K targets. Fragment sphericity increases with increasing projectile energy at 257 K, but no similar trend is observed for 81 K ice. Our results support the hypothesis that the specific projectile energy is a measure for target comminution for a relatively wide range of projectile energies and target masses. We apply our results to the collisional interaction of icy planetary bodies and find that the complete destruction of a target body with radii between 50 m and 100 km· range from 10^(17) to 10^(27) ergs. Energies corresponding to basaltic bodies of the same size range from 10^(18) to 10^(28) ergs. Our experiments suggest that regolith components on icy planets resemble those on rocky planetary bodies in size and shape. We predict that the initial shapes of icy particles in the Saturnian ring system were roughly spherical. The initial mass distribution of ring particles should follow a power law with a slope of ~ - 1.5.


Item Type:Book Section
Related URLs:
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http://adsabs.harvard.edu/abs/1982LPSC...12.1667LADSArticle
Additional Information:© 1981 Lunar and Planetary Institute. Provided by the NASA Astrophysics Data System. The technical assistance of W. Ginn, P. Gelle and M. Long is gratefully acknowledged. We thank S. K. Croft and W. K. Hartmann for constructive and helpful reviews. This work was supported under NASA grant NSG-7129. One of the authors (M.A. Lange) received a grant from the Deutsche Forschungsgemeinschaft. Contribution No. 3611, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125.
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Funding AgencyGrant Number
NASANSG-7129
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
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Caltech Division of Geological and Planetary Sciences3611
Series Name:Lunar and Planetary Institute
Record Number:CaltechAUTHORS:20150213-092357505
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150213-092357505
Official Citation:Fragmentation of Ice by Low Velocity Impact Authors: Lange, M. A. & Ahrens, T. J. Journal: IN: PROCEEDINGS OF THE 12TH LUNAR AND PLANETARY SCIENCE CONFERENCE, vol. 2, 1667-1687. Proceedings Paper.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54818
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Feb 2015 00:10
Last Modified:03 Oct 2019 08:01

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