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Formation of asteroid satellites and doublet craters by planetary tidal forces

Bottke, William F., Jr. and Melosh, H. Jay (1996) Formation of asteroid satellites and doublet craters by planetary tidal forces. Nature, 381 (6577). pp. 51-53. ISSN 0028-0836. doi:10.1038/381051a0.

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APPROXIMATELY ten per cent of the impact structures on the Earth and Venus are doublets—pairs of craters formed by the near-simultaneous impact of asteroids of comparable size. It has been suggested that these doublet craters form from asteroid fragments dispersed by aerodynamic forces during atmospheric entry, or from asteroids that were tidally disrupted by gravitational forces shortly before impact. But to form a doublet, the progenitors of the craters must have been well separated before final impact, which poses problems for both mechanisms. Here we argue that a hitherto undetected population of well separated binary asteroids can explain the occurrence of doublet craters. By modelling asteroids as weak, gravitationally bound aggregates ('rubble piles'), we show that the tidal forces experienced during close encounters with the Earth can generate binary asteroids, in a process similar to that which fragmented the comet Shoemaker–Levy 9 (ref. 7) as it passed by Jupiter. Although the resulting binary asteroids may eventually separate or coalesce before colliding with a planet, repeated close encounters with the Earth maintain a steady-state population that is sufficiently large to explain the observed number of doublet craters.

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Additional Information:© 1996 Nature Publishing Group. Received 7 December 1995; accepted 22 March 1996. We thank E. Asphaug, B.Chauvineau, C. Cook, D. Durda, P. Farinella, R. Greenberg, A. Harris, M. Nolan, D. Richardson and J. Scotti for useful discussions and reviews of this manuscript. This work was partially supported by NASA's Planetary Geology and Geophysics Program and from Texaco Prize Fellowship at Caltech (W.F.B).
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Caltech Texaco Prize FellowshipUNSPECIFIED
Issue or Number:6577
Record Number:CaltechAUTHORS:20150610-104332843
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Official Citation:Formation of asteroid satellites and doublet craters by planetary tidal forces 51 William F. Bottke Jr & H. Jay Melosh doi:10.1038/381051a0
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58152
Deposited By: Ruth Sustaita
Deposited On:10 Jun 2015 18:35
Last Modified:10 Nov 2021 22:00

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