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Science 23 December 1977:
Vol. 198. no. 4323, pp. 1249 - 1251
DOI: 10.1126/science.198.4323.1249-a
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Articles

Meteorite Impact Ejecta: Dependence of Mass and Energy Lost on Planetary Escape Velocity

JOHN D. O'KEEFE 1 and THOMAS J. AHRENS 1

1 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125

The calculated energy efficiency of mass ejection for iron and anorthosite objects striking an anorthosite planet at speeds of 5 to 45 kilometers per second decreases with increasing impact velocity at low escape velocities. At escape velocities of >105 and >2 x 104 centimeters per second, respectively, the slower impactors produce relatively less ejecta for a given impact energy. The impact velocities at which ejecta losses equal meteorite mass gains are found to be approximately 20, 35, and 45 kilometers per second for anorthosite objects and approximately 25, 35, and 40 kilometers per second for iron objects striking anorthosite surfaces for the gravity fields of the moon, Mercury, and Mars.

Submitted on June 24, 1977
Revised on August 22, 1977


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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D. P. Hamilton, D. P. Hamilton, and J. A. Burns (1994)
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Oblique Impact: A Process for Obtaining Meteorite Samples from Other Planets.
J. D. O'Keefe, J. D. O'KEEFE, and T. J. AHRENS (1986)
Science 234, 346-349
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