Abstract
The purpose of this investigation is to study the effect of an impact-generated gas cloud on the size-velocity distribution of large, solid ejecta fragments that become entrained in it, with particular reference to the possible Martian origin of the SNC meteorites. The entrainment both of loose surface boulders and of the early-time, large-size, high-velocity spall component of the crater ejecta is modeled numerically. Surface boulders from as far as 40 km from the center of impact can be accelerated by the high velocity leading edge of the gas cloud to velocities in excess of Martian escape velocity (5 km/s), but are generally crushed by the acceleration. Spall fragments become entrained later and nearer the center of the gas cloud, where gas velocities are much less. High velocity spalls are decelerated by the gas and low velocity spalls are accelerated by the gas, but no spalls ejected at < 5km/s are accelerated to velocities 5km/s. An impact-generated gas cloud is thus expected to scour the pre-existing surface of loose material and to change the size-velocity distribution of spall ejecta, but does not sufficiently enhance the velocities of crater ejecta to explain the Martian origin of SNC meteorites as large rocks.
Published Version
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