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Oblique Impact: A Process for Obtaining Meteorite Samples from Other Planets

O'Keefe, John D. and Ahrens, Thomas J. (1986) Oblique Impact: A Process for Obtaining Meteorite Samples from Other Planets. Science, 234 (4774). pp. 346-349. ISSN 0036-8075. doi:10.1126/science.234.4774.346.

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Cratering flow calculations for a series of oblique to normal (10° to 90°) impacts of silicate projectiles onto a silicate halfspace were carried out to determine whether or not the gas produced upon shock-vaporizing both projectile and target material would form a downstream jet that could entrain and propel SNC meteorites from the Martian surface. The difficult constraints that the impact origin hypothesis for SNC meteorites has to satisfy are that these meteorites are lightly to moderately shocked and yet have been accelerated to speeds in excess of the Martian escape velocity (more than 5 kilometers per second). Two-dimensional finite difference calculations were performed that show that at highly probable impact velocities (7.5 kilometers per second), vapor plume jets are produced at oblique impact angles of 25° to 60° and have speeds as great as 20 kilometers per second. These plumes flow nearly parallel to the planetary surface. It is shown that upon impact of projectiles having radii of 0.1 to 1 kilometer, the resulting vapor jets have densities of 0.1 to 1 gram per cubic centimeter. These jets can entrain Martian surface rocks and accelerate them to velocities greater than 5 kilometers per second. This mechanism may launch SNC meteorites to earth.

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Additional Information:© 1986 American Association for the Advancement of Science. Received 14 March 1986; accepted 11 August 1986. Research supported under NASA grant NSG 7129. We appreciate the assistance of M. Lainhart with the calculations. We are grateful for the helpful comments proffered by G. Wetherill, D. Stevenson, D. Anderson, J. Melosh, B. C. Clark, D. E. Gault, and M. Kovari. Contribution 4137, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
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Caltech Division of Geological and Planetary Sciences4137
Issue or Number:4774
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Official Citation:Oblique Impact: A Process for Obtaining Meteorite Samples from Other Planets John D. O'Keefe and Thomas J. Ahrens Science, New Series, Vol. 234, No. 4774 (Oct. 17, 1986), pp. 346-349 Published by: American Association for the Advancement of Science Article Stable URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51120
Deposited By: Tony Diaz
Deposited On:31 Oct 2014 18:40
Last Modified:10 Nov 2021 19:06

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