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

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Science  23 Dec 1977:
Vol. 198, Issue 4323, pp. 1249-1251
DOI: 10.1126/science.198.4323.1249-a


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.